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Exploring the contribution of common microorganisms to spoilage is of great significance in inhibiting spoilage in lamb. This work investigated the extent of protein degradation and profile changes of free amino acids (FAAs), free fatty acids (FFAs) and volatile organic compounds (VOCs) in lamb caused by single- and co-culture of the common aerobic spoilage bacteria, P. paralactis, Ac. MN21 and S. maltophilia. Meanwhile, some key VOCs produced by the three bacteria during lamb spoilage were also screened by orthogonal partial least square discriminant analysis and difference value in VOCs content between inoculated groups and sterile group. Lamb inoculated with P. paralactis had the higher total viable counts, pH, total volatile base nitrogen and TCA-soluble peptides than those with the other two bacteria. Some FAAs and FFAs could be uniquely degraded by P. paralactis but not Ac. MN21 and S. maltophilia, such as Arg, Glu, C15:0, C18:0 and C18:1n9t. Co-culture of the three bacteria significantly promoted the overall spoilage, including bacterial growth, proteolysis and lipolysis. Key VOCs produced by P. paralactis were 2, 3-octanedione, those by Ac. MN21 were 1-octanol, octanal, hexanoic acid, 1-pentanol and hexanoic acid methyl ester, and that by S. maltophilia were hexanoic acid. The production of extensive key-VOCs was significantly and negatively correlated with C20:0, C23:0 and C18:ln9t degradation. This study can provide a basis for inhibiting common spoilage bacteria and promoting high-quality processing of fresh lamb., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy to meet a growing population's demands. This research aimed to elucidate microbial biostimulants' (Plant Growth Promoting Rhizobacteria) role in alleviating drought stress in oil-seed crops. In total, 15 bacterial isolates were selected for drought tolerance and screened for plant growth-promoting (PGP) attributes like phosphate solubilization and production of indole-3-acetic acid, siderophore, hydrogen cyanide, ammonia, and exopolysaccharide. This research describes two PGPR strains: Acinetobacter calcoaceticus AC06 and Bacillus amyloliquefaciens BA01. The present study demonstrated that these strains (AC06 and BA01) produced abundant osmolytes under osmotic stress, including proline (2.21 and 1.75 µg ml - 1 ), salicylic acid (18.59 and 14.21 µg ml - 1 ), trehalose (28.35 and 22.74 µg mg - 1 FW) and glycine betaine (11.35 and 7.74 mg g - 1 ) respectively. AC06 and BA01 strains were further evaluated for their multifunctional performance by inoculating in Arachis hypogaea L. (Groundnut) under mild and severe drought regimes (60 and 40% Field Capacity). Inoculation with microbial biostimulants displayed distinct osmotic-adjustment abilities of the groundnut, such as growth parameters, plant biomass, photosynthetic pigments, relative water content, proline, and soluble sugar in respective to control during drought. On the other hand, plant sensitivity indexes such as electrolyte leakage and malondialdehyde (MDA) contents were decreased as well as cooperatively conferred plant drought tolerance by induced alterations in stress indicators such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD). Thus, Acinetobacter sp. AC06 and Bacillus sp. BA01 can be considered as osmolyte producing microbial biostimulants to simultaneously induce osmotic tolerance and metabolic changes in groundnuts under drought stress., (© 2024. The Author(s).)

Pretreatment of lignocellulosic biomass produces growth inhibitory substances such as furfural which is toxic to microorganisms. Acinetobacter baylyi ADP1 cannot use furfural as a carbon source, instead it biotransforms this compound into difurfuryl ether using the reduced nicotinamide adenine dinucleotide (NADH)-dependent dehydrogenases AreB and FrmA during aerobic acetate catabolism. However, NADH consumption for furfural biotransformation compromises aerobic growth of A. baylyi ADP1. Depending on the growth phase, several genes related to acetate catabolism and oxidative phosphorylation changed their expression indicating that central metabolic pathways were affected by the presence of furfural. During the exponential growth phase, reactions involved in the formation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) (icd gene) and NADH (sfcA gene) were preferred when furfural was present. Therefore a higher NADH and NADPH production might support furfural biotransformation and biomass production, respectively. In contrast, in the stationary growth phase genes of the glyoxylate shunt were overexpressed probably to save carbon compounds for biomass formation, and only NADH regeneration was appreciated. Finally, disruption of the frmA or areB gene in A. baylyi ADP1 led to a decrease in growth adaptation and in the capacity to biotransform furfural. The characterization of this physiological behavior clarifies the impact of furfural in Acinetobacter metabolism., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Objectives: To determine furfural biotransformation capabilities of Acinetobacter baylyi ADP1 and Acinetobacter schindleri ACE., Results: Acinetobacter baylyi ADP1 and A. schindleri ACE could not use furfural as sole carbon source but when acetate was used as substrate, ADP1 and ACE biotransformed 1 g furfural/l in 5 and 9 h, respectively. In both cases, the product of this biotransformation was difurfuryl-ether as shown by FT-IR and 1 H and 13 C NMR spectroscopy. The presence of furfural decreased the specific growth rate in acetate by 27% in ADP1 and 53% in ACE. For both strains, the MIC of furfural was 1.25 g/l. Nonetheless, ADP1 biotransformed 2 g furfural/l at a rate of 1 g/l/h in the stationary phase of growth. A transcriptional analysis of possible dehydrogenases involved in this biotransformation, identified that the areB and frmA genes were highly overexpressed after the exposure of ADP1 to furfural. The products of these genes are a benzyl-alcohol dehydrogenase and an alcohol dehydrogenase., Conclusions: Acinetobacter baylyi ADP1 is a candidate for the biological detoxification of furfural, a fermentation inhibitor present in lignocellulosic hydrolysates, with the possible direct involvement of the AreB and FrmA enzymes in the process.

A new aerobic denitrifying bacterium ZYL was isolated from domestic wastewater sludge and identified as Acinetobacter haemolyticus (similarity 99%) by the 16S rDNA sequencing analysis. The strain could use nitrate, nitrite and ammonium as the sole N-source for growth with a final product of N 2 , demonstrating its good abilities for aerobic denitrification and heterotrophic nitrification. Single-factor experiment results showed that the effective removal of nitrate by strain ZYL occurred with carbon source sodium succinate, C/N 16-24, pH 5-9, temperature 20-40 °C, DO ≥ 4.84 mg/L. Ammonium was preferentially used by strain ZYL with nitrate and ammonium as the mixed nitrogen sources. According to nitrogen utilization, nitrogen balance analysis, enzyme assay and denitrifying gene amplification, nitrate was assimilated directly by the isolate for cell synthesis and also converted into N 2 through aerobic denitrification. All these make strain ZYL an ideal choice for treating nitrogen-containing wastewater.

Current cleaning and sanitation protocols may not be adequately effective in cleaning separation membranes and can result in the formation of resilient multispecies biofilms. The matured biofilms may result in a bacterial predominance with resilient strains on membranes with a prolonged use. In our previous study, we isolated organisms such as Bacillus subtilis, Bacillus licheniformis, Exiguobacterium aurantiacum, and Acinetobacter radioresistens from an 18-mo-old reverse osmosis membrane. The competitive exclusion studies revealed the predominance of B. subtilis within the membrane biofilm microflora. This study investigated the antimicrobial activity of the B. subtilis isolate as a potential cause of its predominance. The culture isolate was propagated in tryptic soy broth at 37°C, and microfiltered to prepare cell-free extracts (CFE) at 8-, 10-, 12-, 14-, 16-, and 18-h intervals. The CFE were freeze-dried and suspended in minimum quantities of HPLC-grade water to prepare concentrated solutions. The antimicrobial activities of CFE were tested using the agar-well assay against the biofilm constitutive microflora. The experiments were conducted in triplicates and means were compared for significant differences using a general linear mixed model procedure. The results indicated the highest antimicrobial activity of 12-h CFE of B. subtilis against other constitutive microflora such as Exiguobacterium sp., E. auranticum, and A. radioresistens, with average inhibition zone sizes of 16.5 ± 0.00, 16.25 ± 0.66, and 20.6 ± 0.00 mm, respectively. Upon treatment with proteinase K, the CFE completely lost its antimicrobial activity, establishing it to be a proteinaceous compound. The AA profiling revealed the total crude protein in CFE to be 51% (wt/wt), with its major constituent as glutamic acid (11.30% wt/wt). The freeze-dried CFE was thermally stable on exposure to the common temperature used for sanitizer applications (23.8°C for 5 and 10 min) and over a pH range of 3.0 to 6.3. The study helped us understand the role of the antimicrobial compound produced by B. subtilis as a potential cause of its predominance within the biofilm constitutive microflora., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Due to the global threat of rising antimicrobial resistance, novel antibiotics are urgently needed. We investigate natural products from Myxobacteria as an innovative source of such new compounds. One bottleneck in the process is typically the elucidation of their mode-of-action. We recently established isothermal microcalorimetry as part of a routine profiling pipeline. This technology allows for investigating the effect of antibiotic exposure on the total bacterial metabolic response, including processes that are decoupled from biomass formation. Importantly, bacteriostatic and bactericidal effects are easily distinguishable without any user intervention during the measurements. However, isothermal microcalorimetry is a rather new approach and applying this method to different bacterial species usually requires pre-evaluation of suitable measurement conditions. There are some reference thermograms available of certain bacteria, greatly facilitating interpretation of results. As the pool of reference data is steadily growing, we expect the methodology to have increasing impact in the future and expect it to allow for in-depth fingerprint analyses enabling the differentiation of antibiotic classes.

Sixteen derivatives of dithiin diisoimide 2a-2p have been synthesized and screened for antibacterial and antifungal activity. Compounds 2a-2g and 2i-2p are almost same or more active than gentamicine against Acinetobacter. Whereby compound 2,6-didodecyl- 1 H,5H-pyrrolo[3',4',5,6][1,4]dithiino[2,3-c]pyrrole-1,3,5,7(2H,6H)-tetrone (2d) having zone of inhibition 20 mm against Acinetobacter is the most potent among all these compounds and can be used as lead compound for the treatment of Acinetobacter infection.

A. johnsonii and P. fluorescens are the well-known specific spoilage organisms in aquatic products and the study of the interactions between A. johnsonii and P. fluorescens are limited. This study aims to evaluate the growth kinetics, spoilage potential and interactions of A. johnsonii and P. fluorescens isolated from spoiled bigeye tuna (Thunnus obesus) by inoculating into sterile fish slices and stored at 4 °C for 6 days. The growth kinetics of A. johnsonii and P. fluorescens were fitted with Baranyi and Roberts model. The chemical indexes (total volatile base nitrogen (TVB-N), trimethylamine (TMA), pH, proteolytic activity and protein content) of each inoculated block of bigeye tuna were increased during refrigerated storage. Moreover, the higher contents of chemical indexes were observed in co-culture with A. johnsonii and P. fluorescens compared with single culture of A. johnsonii and P. fluorescens. In addition, atomic force microscopy (AFM) observation of co-culturing A. johnsonii and P. fluorescens inoculation into sterile fish slices revealed damage of myofibrillar protein structures and the protein degradation. Based on these parameters, a rapid method to evaluate spoilage potential of A. johnsonii and P. fluorescens was positively correlated with TVB-N value, TMA value and pH value (P < 0.05) by the correlation coefficient. Consequently, spoilage potential of microorganisms became stronger evaluated in a mixed culture than single culture. This paper provides insight for a detection method of interactions of A. johnsonii and P. fluorescens during refrigerated storage.

One goal of synthetic biology is to improve the efficiency and predictability of living cells by removing extraneous genes from their genomes. We demonstrate improved methods for engineering the genome of the metabolically versatile and naturally transformable bacterium Acinetobacter baylyi ADP1 and apply them to a genome streamlining project. In Golden Transformation, linear DNA fragments constructed by Golden Gate Assembly are directly added to cells to create targeted deletions, edits, or additions to the chromosome. We tested the dispensability of 55 regions of the ADP1 chromosome using Golden Transformation. The 18 successful multiple-gene deletions ranged in size from 21 to 183 kb and collectively accounted for 23.4% of its genome. The success of each multiple-gene deletion attempt could only be partially predicted on the basis of an existing collection of viable ADP1 single-gene deletion strains and a new transposon insertion sequencing (Tn-Seq) dataset that we generated. We further show that ADP1's native CRISPR/Cas locus is active and can be retargeted using Golden Transformation. We reprogrammed it to create a CRISPR-Lock, which validates that a gene has been successfully removed from the chromosome and prevents it from being reacquired. These methods can be used together to implement combinatorial routes to further genome streamlining and for more rapid and assured metabolic engineering of this versatile chassis organism., (© The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.)

This study investigated the effect of phytic acid and lysozyme on the microbial composition and quality of grass carp (Ctenopharyngodon idellus) fillets stored at 4 °C. The control, 0.5 mg/mL lysozyme-treated fillets (T1), 0.5 mg/mL phytic acid-treated fillets (T2) and 0.25 mg/mL lysozyme + 0.25 mg/mL phytic acid-treated fillets (T3) were evaluated based on sensory assessment, biogenic amines, ATP-related compounds, total volatile basic nitrogen (TVB-N), and total viable counts (TVC). Changes in microbial composition were analyzed using high-throughput sequencing. Results showed that phytic acid and lysozyme treatment delayed the decrease in sensory scores, reduced the rate of degradation of IMP to Hx, inhibited the growth of microorganisms, and attenuated the increase in TVB-N and putrescine. Phytic acid exhibited better preservation effects than lysozyme and their combination was more effective than using either alone. High-throughput sequencing showed that Acinetobacter and Kocuria were the predominant bacteria in fresh grass carp, but Pseudomonas rose rapidly with storage time; Pseudomonas, Shewanella, and Aeromonas constituted the main spoilage bacteria of grass carp fillets. Lysozyme treatment significantly reduced the proportion of Shewanella and Acinetobacter, and phytic acid and the combination of phytic acid and lysozyme significantly reduced the proportion of Pseudomonas in spoiled grass carp fillets., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Acinetobacter baylyi ADP1 is an ideal bacterial strain for high-throughput genetic analysis as the bacterium is naturally transformable. Thus, ADP1 can be used to investigate DNA mismatch repair, a mechanism for repairing mismatched bases. We used the mutS deletion mutant (XH439) and mutL deletion mutant (XH440), and constructed a mutS mutL double deletion mutant (XH441) to investigate the role of the mismatch repair system in A. baylyi., Results: We determined the survival rates after UV irradiation and measured the mutation frequencies, rates and spectra of wild-type ADP1 and mutSL mutant via rifampin resistance assay (Rif R assay) and experimental evolution. In addition, transformation efficiencies of genomic DNA in ADP1 and its three mutants were determined. Lastly, the relative growth rates of the wild type strain, three constructed deletion mutants, as well as the rifampin resistant mutants obtained from Rif R assays, were measured. All three mutants had higher survival rates after UV irradiation than wild type, especially the double deletion mutant. Three mutants showed higher mutation frequencies than ADP1 and favored transition mutations in Rif R assay. All three mutants showed increased mutation rates in the experimental evolution. However, only XH439 and XH441 had higher mutation rates than the wild type strain in Rif R assay. XH441 showed higher transformation efficiency than XH438 when donor DNA harbored transition mutations. All three mutants showed higher growth rates than wild-type, and these four strains displayed higher growth rates than almost all their rpoB mutants. The growth rate results showed different amino acid mutations in rpoB resulted in different extents of reduction in the fitness of rifampin resistant mutants. However, the fitness cost brought by the same mutation did not vary with strain background., Conclusions: We demonstrated that inactivation of both mutS and mutL increased the mutation rates and frequencies in A. baylyi, which would contribute to the evolution and acquirement of rifampicin resistance. The mutS deletion is also implicated in increased mutation rates and frequencies, suggesting that MutL may be activated even in the absence of mutS. The correlation between fitness cost and rifampin resistance mutations in A. baylyi is firstly established.

The presence of diesel in the water could reduce the growth of plant and thus phytoremediation efficacy. The toxicity of diesel to plant is commonly explained; because of hydrocarbons in diesel accumulate in various parts of plants, where they disrupt the plant cell especially, the epidemis, leaves, stem and roots of the plant. This study investigated the effect of bacterial augmentation in floating treatment wetlands (FTWs) on remediation of diesel oil contaminated water. A helophytic plant, Phragmites australis (P. australis), was vegetated on a floating mat to establish FTWs for the remediation of diesel (1%, w/v) contaminated water. The FTWs was inoculated with three bacterial strains (Acinetobacter sp. BRRH61, Bacillus megaterium RGR14 and Acinetobacter iwoffii AKR1), possessing hydrocarbon degradation and plant growth-enhancing capabilities. It was observed that the FTWs efficiently removed hydrocarbons from water, and bacterial inoculation further enhanced its hydrocarbons degradation efficacy. Diesel contaminated water samples collected after fifteen days of time interval for three months and were analyzed for pollution parameters. The maximum reduction in hydrocarbons (95.8%), chemical oxygen demand (98.6%), biochemical oxygen demand (97.7%), total organic carbon (95.2%), phenol (98.9%) and toxicity was examined when both plant and bacteria were employed in combination. Likewise, an increase in plant growth was seen in the presence of bacteria. The inoculated bacteria showed persistence in the water, root and shoot of P. australis. The study concluded that the augmentation of hydrocarbons degrading bacteria in FTWs is a better option for treatment of diesel polluted water., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A calcium precipitating and denitrifying bacterium H12 was used to investigate the F - removal performance and mechanism. The results showed that the strain H12 reduced 85.24% (0.036 mg·L -1 ·h -1 ) of F - , 62.43% (0.94 mg·L -1 ·h -1 ) of Ca 2+ , and approximately 100% of NO 3 - over 120 h in continuous determination experiments. The response surface methodology analysis demonstrated that the maximum removal efficiency of F - was 88.98% (0.062 mg·L -1 ·h -1 ) within 72 h under the following conditions: the initial Ca 2+ concentration of 250.00 mg·L -1 , pH of 7.50, and the initial C 4 H 4 Na 2 O 4 ·6H 2 O concentration of 800.00 mg·L -1 . The scanning electron microscopy images, the X-ray photoelectron spectroscopy, and X-ray diffraction results suggested the following removal mechanism of F - : (1) the bacteria, as the nucleation site, were encapsulated by bioprecipitation to form biological crystal seeds; (2) Biological crystal seeds adsorbed F - to form Ca 5 (PO 4 ) 3 F and CaF 2 ; (3) Under the induction of bacteria, calcium, fluoride and phosphate coprecipitated to form Ca 5 (PO 4 ) 3 F and CaF 2 . In addition, the gas chromatography data indicated that F - had little or no effect on the gas composition during denitrification, and the fluorescence spectroscopy analysis also proved that the extracellular polymeric substance (protein) is the site of bioprecipitation nucleation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Diverse interactions among species within bacterial colonies lead to intricate spatiotemporal dynamics, which can affect their growth and survival. Here, we describe the emergence of complex structures in a colony grown from mixtures of motile and non-motile bacterial species on a soft agar surface. Time-lapse imaging shows that non-motile bacteria 'hitchhike' on the motile bacteria as the latter migrate outward. The non-motile bacteria accumulate at the boundary of the colony and trigger an instability that leaves behind striking flower-like patterns. The mechanism of the front instability governing this pattern formation is elucidated by a mathematical model for the frictional motion of the colony interface, with friction depending on the local concentration of the non-motile species. A more elaborate two-dimensional phase-field model that explicitly accounts for the interplay between growth, mechanical stress from the motile species, and friction provided by the non-motile species, fully reproduces the observed flower-like patterns., Competing Interests: LX, YC, RC, WR, JH, LT No competing interests declared, (© 2020, Xiong et al.)

Pollution of aquatic resources is increasing day-by-day, and phenolic compounds are common pollutants negatively impacting aquatic biodiversity and production. This study aimed at isolation of phenol hyper-tolerant bacteria from polluted aquaculture resource so that they might be useful in aquaculture systems. Four phenol hyper-tolerant bacterial strains were isolated from sewage fed East Kolkata Wetlands, a Ramsar site. By 16S rDNA sequence, cell morphology and biochemical characteristics the strains PDB2, PDB13, PDB16, and PDB26 were identified as Acinetobacter sp., Acinetobacter junii , Pseudomonas citronellolis , and Bacillus cereus , respectively . Pseudomonas citronellolis strain PDB16, described in this study, is possibly the first report of phenol hyper-tolerant strain in this species. All the four strains degraded 600 mg L -1 phenol within 5 days and expressed catechol 1,2-dioxygenase but lacked catechol 2,3-dioxygenase enzyme suggesting that the bacteria used the ortho-cleavage pathway for phenol degradation. In growth kinetic study Edwards and Aiba model, rather than the most popular Haldane model, gave the best fit indicating behavioral divergence of these strains with those from petroleum contaminated environments. The phenol degrading bacteria isolated from a polluted sewage fed aquaculture system might be useful in degradation and remediation of polluted aquaculture resources as well as inland open waters.

Engineered microbial consortia can provide several advantages over monocultures in terms of utilization of mixed substrates, resistance to perturbations, and division of labor in complex tasks. However, maintaining stability, reproducibility, and control over population levels in variable conditions can be challenging in multispecies cultures. In our study, we modeled and constructed a synthetic symbiotic consortium with a genetically encoded carbon cross-feeding system. The system is based on strains of Escherichia coli and Acinetobacter baylyi ADP1, both engineered to be incapable of growing on glucose on their own. In a culture supplemented with glucose as the sole carbon source, growth of the two strains is afforded by the exchange of gluconate and acetate, resulting in inherent control over carbon availability and population balance. We investigated the system robustness in terms of stability and population control under different inoculation ratios, substrate concentrations, and cultivation scales, both experimentally and by modeling. To illustrate how the system might facilitate division of genetic circuits among synthetic microbial consortia, a green fluorescent protein sensitive to pH and a slowly maturing red fluorescent protein were expressed in the consortium as measures of a circuit's susceptibility to external and internal variability, respectively. The symbiotic consortium maintained stable and linear growth and circuit performance regardless of the initial substrate concentration or inoculation ratio. The developed cross-feeding system provides simple and reliable means for population control without expression of non-native elements or external inducer addition, being potentially exploitable in consortia applications involving precisely defined cell tasks or division of labor.

Background: A nano-scale surface coating containing silicon nanoparticles (Bacterlon®) creates a hydrophobic surface which prevents the growth of bacteria. Study objective was to evaluate the performance of this silicon nano-coating in Sri Lankan healthcare setting., Methods: This prospective study was conducted from September 2015 to December 2015 in an Intensive Care Unit and a medical ward in Base Hospital Homagama and a bacteriology laboratory in Medical Research Institute, Colombo, Sri Lanka. Silicon nanoparticle coating was applied to 19 high touch surfaces from those three sites. During the follow-up period, these test sites and non-coated control sites were used for routine work and were cleaned routinely as per institute protocol. Swabbing was done for coated and non-coated sites once a week for 12 weeks at unannounced times. Surfaces were categorized in to low (≤10 CFU/cm 2 ) and high (>10-99 CFU/cm 2 ) contamination by Aerobic Bacterial Count (ABC) in non-coated sites at any given time., Results: In low and high contaminated surfaces, an improvement in the mean percentage bioburden reduction from 36.18% to 50.16% was observed from 4th week to 12th week with silicon nanoparticles and a significant reduction (p < 0.05) was seen in ABC in each of the coated surface compared with their non-coated counterpart by the 12th week. The frequency of isolation of Acinetobacter spp. on coated surfaces had a significant reduction (p < 0.01)., Conclusion: Silicon nanoparticle coating demonstrates a significant reduction of the bacterial bioburden in low and high contaminated surfaces for 12 weeks in a tropical healthcare setting., (Copyright © 2019 Australasian College for Infection Prevention and Control. Published by Elsevier B.V. All rights reserved.)

Low permeability oil reservoirs are a widespread petroleum reservoir type all over the world. Therefore, methods to recover these reservoirs efficiently are of importance to guarantee energy supply. Here we report our novel stimulation of indigenous microbes by optimizing the water cut in low permeability reservoirs for green and enhanced oil recovery. We aimed to investigate the characteristics of indigenous bacterial communities with changes in water cut in reservoirs by high-throughput sequencing technology, and reveal the mechanism and characteristics of the crude oil biotreatment under different crude oil-water ratio conditions and the optimum activation time of indigenous functional microbial groups in reservoirs. The indigenous microbial metabolism products were characterized by gas chromatography mass spectrometry. Results showed that Acinetobacter (47.1%) and Pseudomones (19.8%) were the main functional genus of crude oil degradation at the optimal activation time, and can reduce the viscosity of crude oil from 8.33 to 5.75 mPa·s. The dominant bacteria genus for oil recovery after activation of the production fluids was similar to those in the reservoirs with water cut of 60-80%. Furthermore seven mechanism pathways of enhancing oil recovery by the synergistic of functional microbial groups and their metabolites under different water cut conditions in low permeability reservoirs have been established.

The Acinetobacter sp. strain M isolated from a contaminated soil sample in Jiangsu Province of China was found to be able to degrade perfluorooctane sulfonamide (PFOSA) effectively. Fluoride anion (F - ) released from PFOSA degradation was detected by ion chromatography, and showed positive correlation to the growth curve of Acinetobacter sp. strain M. The PFOSA degradation efficiency of strain M was approximately 27 %, as assessed by GC analysis. It was shown that enzymes localized outside of cells of Acinetobacter sp. strain M catalyzed the degradation of PFOSA. This further indicates a possibly new (multi-step/pathway) mechanism for PFOSA degradation. It revealed that the extracellular enzyme of the Acinetobacter strain M preferentially cleaves carbon-carbon and carbon-fluorine bonds instead of destroying the carbon-sulfur bond. The growth condition for Acinetobacter sp. strain M was optimized at 30 °C and pH 7.0 in the presence of 2000 mg L -1 of PFOSA and 0.5 % (v/v) of Tween-20. The optimal PFOSA degradation time was found to be 12 h, with a degradation efficiency of 76 % by extracellular enzymes in strain M as determined by GC analysis. The result may provide potential applications for biodegradition of perfluoro organic compounds, such as derivatives of perfluorooctane (C8)., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Acinetobacter baylyi ADP1 is a microorganism with the potential to produce storage lipids. Here, a systematic study was carried out to evaluate growth performance and accumulation of wax esters and triacylglycerols using glycerol, xylose, glucose, acetate, ethanol, and pyruvate as carbon sources. High specific growth rates (μ) were found in gluconeogenic carbon sources (ethanol, acetate, and pyruvate: 0.94 ± 0.18, 0.93 ± 0.06, and 0.61 ± 0.01 h -1 , respectively), and low in glucose (0.25 ± 0.01 h -1 ). Interestingly, these μ values were sustained in a broad range of concentrations of glucose (0.5-50 g L -1 ), pyruvate (3-10 g L -1 ), and acetate (0.3-2 g L -1 ), suggesting a high tolerance to glucose and pyruvate. It was observed that ADP1 is not able to use glycerol or xylose as unique carbon sources. On the other hand, ADP1 showed sensitivity to osmotic upshifts, noted by the lysis at the beginning of cultivations on different carbon sources. However, ADP1 is adapted to relatively high substrate concentrations as indicated by the minimal inhibitory concentrations (MICs) determined at 24 h of cultivations: 350, 50, 80, and 15 g L -1 for glucose, ethanol, pyruvate, and acetate, respectively. Remarkably, ADP1 co-utilized glucose, acetate, ethanol, and pyruvate. Finally, the accumulation of storage lipids, wax esters (WEs), and triacylglycerols (TAGs) showed to be substrate dependent. Under nitrogen-limiting conditions, the TAGs:WEs (mol:mol) accumulation ratios were 1:4.9 in pyruvate and 1:1.6 in glucose, the WEs were mainly accumulated in acetate. In ethanol, no accumulation of lipids was detected.

This study investigated the factors influencing the simultaneous removal of Cd 2+ , NO 3 -N and hardness from water by the bacterial strain CN86. Optimum conditions were determined experimentally by varying the type of organic matter used, initial Cd 2+ concentration, and pH. Under the optimum conditions, the maximum removal ratios of Cd 2+ , NO 3 -N and hardness were 100.00, 89.85 and 71.63%, respectively. The mechanism of Cd 2+ removal is a combination of co-precipitation with calcium carbonate and pH. Further confirmation that Cd 2+ can be removed by strain CN86 was provided by XRD and XPS analyses. Meteorological chromatography analysis showed that N 2 was produced as an end product. These results demonstrate that the bacterial strain CN86 is a suitable candidate for simultaneously removing Cd 2+ , NO 3 -N, and hardness during in wastewater treatment.

A phase 1 clinical study was performed to assess the pharmacokinetics and safety of intravenous (i.v.) administration of colistin methanesulfonate (CMS) and azidothymidine (AZT) alone and in combination. Seven healthy subjects received three (every 12 h) 1-h i.v. infusions of 4, 2 and 2 million international units (MIU) of CMS co-administered with 200, 100 and 100 mg of AZT, respectively. In an ex vivo study, urinary bactericidal titres (UBTs) and time-kill curve determinations were performed in artificial urine spiked with colistin sulfate and AZT according to median and minimum peak concentrations in urine measured after the first and third dose using four mcr-1-positive colistin-resistant and five colistin-susceptible Gram-negative isolates. Reciprocal UBTs for the different colistin concentrations obtained in urine ranged from 1-128 and 0-2 for colistin-susceptible and colistin-resistant isolates, respectively. Combination with AZT could increase UBTs up to two dilution steps each for the Enterobacteriaceae and Acinetobacter strains tested. In contrast, the combination had no activity against Pseudomonas strains. In time-kill curves, the combination showed bactericidal activity against colistin-resistant strains even when the substances alone were not bactericidal. Thus, combination of CMS with AZT shows promising synergistic activity against Gram-negative uropathogens, including colistin-resistant Enterobacteriaceae. According to the urinary bactericidal activity, a maintenance dosage of 2 MIU of CMS combined with 100 mg of AZT twice daily may be sufficient for the treatment of urinary tract infections (UTIs) caused by colistin-susceptible strains. However, the dosage requires optimisation for efficient treatment of UTIs caused by colistin-resistant strains., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Prepared foods have received increasing attention owing to their convenience, rapidness, and ease of processing in a fast-paced life. The bacterial diversity and composition vary among different prepared foods and are closely related to food safety and human health. However, the knowledge on the bacterial community in prepared foods is still limited. In this study, the bacterial diversity in three kinds of prepared foods (meat, aquatic, and dish) available at supermarkets in Beijing was examined by using the high throughput sequencing technology to identify bacterial 16S rRNA genes. Alpha diversity analysis indicated that Proteobacteria and Firmicutes were the predominant bacterial phyla in prepared meat products, which accounted for 35-49% and 42-58% of the total sequences, respectively. Similar results were observed in prepared aquatic products, except salmon, which had a relatively unique bacterial community with Proteobacteria accounting for 90.72%. In prepared dishes, the proportions of Proteobacteria and Firmicutes were about 39-74% and 8-37%, respectively. The predominant bacterial genera detected in all samples within each kind of prepared foods were used to examine the differences in the bacterial community among three kinds of prepared foods. Results showed that the bacterial community in prepared meat products was much more diverse (14 genera) than those in prepared aquatic products (6 genera) and prepared dishes (2 genera). Acinetobacter was detected in all 288 prepared products. The bacterial community structures of prepared meat and aquatic products were more similar compared to those of prepared dishes. On the other hand, in prepared meat products, the bacterial communities of the samples with the same materials or brands were more similar, and further, among the sample with the same brands, the bacterial communities of the samples from the development zone were clearly different from those of the samples from the main urban area. In prepared aquatic products, the bacterial communities of the samples from the same region were also more similar. In prepared dish products, the bacterial communities of the samples with the same foodstuff or cooking style were more similar. In conclusion, this study revealed that the origin and type of prepared food ingredients, along with the sales location and processing methods, influenced microbial diversity and composition., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Metal contamination exerts environmental pressure on several lifeforms. Since metals are non-biodegradable and recalcitrant, they accumulate in living beings and spread through the food chain. Thus, many life forms are affected by environmental metal contamination, such as plants and microorganisms. In the case of microorganisms, scarce information is available on how metals affect them. As a highly resistant form of life, microorganisms can adapt to several environmental pressures through genetic modifications, changing their metabolism to overcome new conditions, and continuing to thrive in the same place. In this study, an Acinetobacter sp. strain was isolated from a copper mine, which presented very high resistance to copper, growing in copper concentrations of up to 7 mM. As a result of its metabolic response in the presence of 3 mM of copper, the expression of 35 proteins in total was altered. The proteins were identified to be associated with the glycolytic pathway, membrane transport, biosynthesis and two proteins directly involved in copper homeostasis (CopA and CopB).

Background: Colonisation with carbapenemase-producing Enterobacteriaceae or Acinetobacter (CPE/A) is associated with complex medical care requiring implementation of specific isolation policies and limitation of patient discharge to other medical facilities. Faecal microbiota transplantation (FMT) has been proposed in order to reduce the duration of gut colonisation., Objectives: This study investigated whether a dedicated protocol of FMT could reduce the negativation time of CPE/A intestinal carriage in patients whose medical care has been delayed due to such colonisation., Method: A matched case-control retrospective study between patients who received FMT treatment and those who did not among CPE/A-colonised patients addressed for initial clustering at the current institute. The study adjusted two controls per case based on sex, age, bacterial species, and carbapenemase type. The primary outcome was delay in negativation of rectal-swab cultures., Results: At day 14 post FMT, 8/10 (80%) treated patients were cleared for intestinal CPE/A carriage. In the control group, 2/20 (10%) had spontaneous clearance at day 14 after CPE/A diagnosis. Faecal microbiota transplantation led patients to reduce the delay in decolonisation (median 3 days post FMT for treated patients vs. 50.5 days after the first documentation of digestive carriage for control patients) and discharge from hospital (median 19.5 days post FMT for treated patients vs. 41 for control patients)., Conclusion: Faecal microbiota transplantation is a safe and time-saving procedure to discharge CPE/A-colonised patients from the hospital. A standardised protocol, including 5 days of antibiotic treatment, bowel cleansing and systematic indwelling devices removal, should improve protocol effectiveness., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Tragacanth, a highly branched carbohydrate polymer isolated from Astragalus, is one of the most commonly used gums in food industry. The primary structure of tragacanth is composed of galacturonic acid monomers connected with α 1-4 links, and it is very similar to the pectin. Tragacanth degradation by microorganisms is significant in two aspects: first, food preservation and microbial growth control due to too much use of tragacanth in the food industry, second, therapeutic and pharmaceutical potential of obtained oligosaccharides. In the present study, we report three new strains of bacteria, Acinetobacter guillouiae strain TD1, Kosakonia sacchari strain TD2, and Bacillus vallismortis strain PD1 with the capability of growing in tragacanth as an only source of carbon and energy. The evolutionary history of the isolated strains was analyzed based on 16S rRNA gene sequences in MEGA7 using the neighbor-joining method. The production of di and tri galacturonic acid due to pectinase activities of the strains were detected by thin layer chromatography (TLC) and liquid chromatography/Mass spectroscopy (LC/MS) analysis. Here is the first report of the ability to grow in tragacanth and pectinase activity monitoring in bacteria. Our results revealed that all of the isolated strains are capable of degrading pectin and tragacanth to oligo-galacturonic acids. The obtained products, which have different structures depending on the tragacanth structures and types of pectinolytic enzymes, would show therapeutic and pharmaceutical potentials., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

High levels of arsenic present in the High Altitude Andean Lakes (HAALs) ecosystems selected arsenic-resistant microbial communities which are of novel interest to study adaptations mechanisms potentially useful in bioremediation processes. We herein performed a detailed characterization of the arsenic tolerance profiles and the biofilm production of two HAAL polyextremophiles, Acinetobacter sp. Ver3 (Ver3) and Exiguobacterium sp. S17 (S17). Cellular adherence over glass and polypropylene surfaces were evaluated together with the effect of increasing doses and oxidative states of arsenic over the quality and quantity of their biofilm production. The arsenic tolerance outcomes showed that HAAL strains could tolerate higher arsenic concentrations than phylogenetic related strains belonging to the German collection of microorganisms and cell cultures (Deutsche Sammlung von Mikroorganismen und Zellkulturen, DSMZ), which suggest adaptations of HAAL strains to their original environment. On the other hand, the crystal violet method (CV) and SEM analysis showed that Ver3 and S17 were able to attach to solid surfaces and to form the biofilm. The quantification of biofilms production in 48 hours' cultures through CV shows that Ver3 yielded higher production in the treatment without arsenic cultured on a glass support, while S17 yield higher biofilm production under intermediate arsenic concentration on glass supports. Polypropylene supports had negative effects on the biofilm production of Ver3 and S17. SEM analysis shows that the highest biofilm yields could be associated with a larger number of attached cells as well as the development of more complex 3D multicellular structures.

Acinetobacter baumanni is recognized as one of the most important agents of nosocomial infections. Other species such as Acinetobacter lwoffii have also been associated with such infections. These species can be found in food products, such as vegetables, fruits and meats which can be a source of transmission of these organisms to community and hospital settings. Evidence that hospitals' kitchens are a route of entry of pathogenic and antimicrobial-resistant bacteria was recently demonstrated. This study aimed to determine whether different Acinetobacter spp. isolated from human and food samples (lettuce, turkey meat, apple and pear) were resistant to stress conditions often applied in food processes, such as exposure to 60 °C, AMUKINA ® and vinegar. Also the influence of food matrices on the behavior of isolates to these stress conditions was evaluated. Treatment with AMUKINA ® and vinegar were effective against all clinical and food isolates. Exposure to 60 °C resulted in the reduction of the majority of isolates to values below the detection limit of the enumeration technique, however, it is important to note that most of the reductions only occurred after 30 min of exposure. One food isolate identified as A. baumanni was resistant to this thermal treatment and one clinical isolate only decreased 4 log cycles after 1 h. In general, food isolates were demonstrated to be more resistant than clinical isolates and no significant differences (p > 0.05) were found between A. baumanni and A. lwoffii species. With the exception of one food isolate that was more resistant to thermal stress in the presence of turkey meat, the food matrices investigated did not confer protection to the applied stresses. Due to the limited knowledge on this topic, we believe that this study is an important contribution to understanding the behavior of Acinetobacter spp. when exposed to treatments commonly applied to foods., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

3-Methylindole (3MI) or Skatole is a volatile lipophilic organic compound produced by anoxic metabolism of L-tryptophan and associated with animal farming and industrial processing wastes. Pure cultures of bacteria capable of utilizing 3MI were isolated from chicken manure using enrichment culture techniques. The bacteria were identified as Acinetobacter toweneri NTA1-2A and Acinetobacter guillouiae TAT1-6A, based on 16S rDNA gene amplicon sequence data. The optimal temperature and pH for degradation of 3MI were established using single factor experiments. Strain tolerance was assessed over a range of initial concentrations of 3MI, and the effects of initial concentration on subsequent microbial 3MI degradation were also measured. During the degradation experiment, concentrations of 3MI were quantified by reverse-phase high-performance liquid chromatography (HPLC). The strains were capable of degrade initial concentrations of 3MI ranging from 65-200 mg/L. The degradation efficiency was >85% in 6 days for both strains when the initial concentration is less than 200 mg/L. The strains were tested for enzymatic activity using 65 mg/L 3MI. The enzyme extracts of NTA1-2A and TAT1-6A from the 3MI medium degraded 71.46% and 60.71% of 3MI respectively, but no appreciable change in 3MI concentration in the control group was witnessed. Our experiment revealed betaine and choline were identified as 3MI degradation metabolites by both strains while nitroso-pyrrolidine and beta-alaninebetaine formed by NTA1-2A and TAT1-6A strains respectively. The NTA1-2A and TAT1-6A strains removed 84.32% and 81.39% 3MI respectively from chicken manure during fermentation in 8 days and showed a statistically significant difference (P < 0.05) compared with the control group. The optimum temperature and pH were 31°C and 6 respectively, for 3MI degradation by A. toweneri NTA1-2A and A. guillouiae TAT1-6A. We concluded that A. toweneri NTA1-2A and A. guillouiae TAT1-6A are potential strains of interest to degrade 3MI and control odorant in poultry and other livestock industries., Competing Interests: The authors have declared that no competing interests exist.

Microplastics are a global concern in aquatic ecology and are readily colonized by bacteria in the environment. There is a lack of information on bacterial colonization of eroded and un-eroded microplastics in freshwater. In this study, six types of microplastics were incubated for 8 weeks in microcosms with water from Lake Erie. Microcosms were inoculated with one of three species: Acinetobacter (A.) calcoaceticus, Burkholderia (B.) cepacia, and Escherichia (E.) coli. These bacterial species are ubiquitous in water bodies associated with human populations. Bacterial surface coverage was determined using electron and fluorescent microscopy. Quantifications of EPS and surface roughness were performed by confocal microscopy and measuring contact angles (θ w ) of water droplets on microplastics, respectively. Analyses revealed surface coverage differed among bacterial species and plastic types after 8 weeks. As the study progressed, E. coli remained the most abundant while A. calcoaceticus gradually decreased on most surfaces. Analyses of microcosms revealed polypropylene disks had lower bacterial abundance. Conversely, eroded polypropylene disks had highest bacterial abundance, indicating importance of surface roughness (lower θ w values) and surface physicochemical properties of microplastics in bacterial colonization. Our results demonstrated that bacterial colonization of microplastics is affected by both the physicochemical properties of microplastics and the physiological properties of colonizing bacteria., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This study investigated the effectiveness of bioelectrokinetics in rehabilitating a silty clayey sand contaminated with diesel fuel using three novel bacterial strains; Acinetobacter calcoaceticus, Sphingobacterium multivorum, and Sinorhizobium, isolated form agriculture land. Three electrokinetic bioremediation cells were used to conduct the tests and a novel electrode configuration technique was used to stabilize pH and water content in the soil specimen. Solar photovoltaic panels were used to generate sustainable energy for the process. The tests were carried out in outdoors for 55 days. Applied voltage, current passing through the electrokinetic cell, and the temperature of the soil specimen were recorded periodically during the test. The pH, water content, and diesel concentration were determined at the end of the tests. Over the test period, the voltage typically increased from zero before sunrise, remained relatively stabilized for about 4 h, and then started to decrease and dropped to zero by sunset. The temperatures in the cells were found to be 5-7 °C higher than the ambient temperature. The innovative electrode configuration succeeded in keeping the pH of soil to remain the same and thereby prevented the development of a pH gradient in the soil, an important development for survival of the bacteria. The diesel degradation in the soil after bioelectrokinetics were 20-30%, compared to 10-12% in the control test. The study was successful in developing environmentally friendly technology employing novel bacterial strains to degrade diesel fuel and utilizing solar panel to produce renewable energy for bioelectrokinetic during the winter season.

This study explores the potential of lead resistant bacterium Acinetobacter junii Pb1 for adsorption/accumulation of lead using various techniques. In the present work, growth of A. junii Pb1 was investigated in the presence of a range of Pb(II) concentrations (0, 100, 250, 500, and 1000 mg l -1 ). Lead was found to have no toxic effect on the growth of A. junii Pb1 at 100 and 250 mg l -1 concentrations. However, further increase in Pb(II) concentration (500 mg l -1 ) showed increase in lag phase, though growth remained unaffected and significant growth inhibition was observed when concentration was increased to 1000 mg l -1 . Same was confirmed by the observations of flow cytometry. Further, the effect of Pb(II) on A. junii Pb1 was evaluated by using fluorescence microscopy, spectrofluorimetry, and flow cytometry. The spectrofluorimetry and fluorescence microscopy results revealed the accumulation of Pb(II) inside the bacterial cells as evident by green fluorescence due to lead binding fluorescent probe, Leadmium Green AM dye. Flow cytometry observations indicate an increase in cell size and granularity of exposure to lead. Thus, present work provides a new understanding of Pb(II) tolerance in A. junii Pb1 and its potential use in remediation of lead from contaminated soil.

Background: Burkholderia pseudomallei is the causative agent of melioidosis, a disease endemic throughout the tropics., Methods: A study of reported Acinetobacter spp. bacteraemia was performed at Chiang Rai provincial hospital from 2014 to 2015. Isolates were collected and tested for confirmation., Results: A total of 419 putative Acinetobacter spp. isolates from 412 patients were re-identified and 5/419 (1.2%) were identified as B. pseudomallei. Four of the five patients with melioidosis died. An estimated 88/419 (21%) isolates were correctly identified as Acinetobacter spp., Conclusions: Misidentification of Acinetobacter spp. as B. pseudomallei or other bacteria is not uncommon and programmes to address these shortfalls are urgently required.

This study evaluated the antimicrobial effects of tea polyphenols (TP) on changes in microbiota composition and quality attributes in silver carp fillets stored at 4 °C. During storage, TP treatment was found to be effective in enhancing sensory quality, inhibiting microbial growth, and attenuating chemical quality deterioration. Meanwhile, the composition of microbiota of silver carp fillets was investigated using culture-dependent and culture-independent methods. Initially, compared to the control, TP obviously decreased the relative abundance of Aeromonas, which allowed Acinetobacter and Methylobacterium to become the dominant microbiota in TP treated fillets on day 0. The controls, 0.5% TP-treated fillets, and 1% TP-treated fillets were rejected by sensory panelists on days 8, 12, and 12, respectively. At the time of sensory rejection, Aeromonas, followed by Acinetobacter and Pseudomonas, became the main spoilers in the control on day 8. However, TP treatment inhibited the growth of Aeromonas and Acinetobacter significantly. Consequently, Aeromonas followed by Pseudomonas and Shewanella became the predominant microbiota in all TP-treated fillets on day 12. Therefore, TP improved the quality of fillets during chilled storage, which was mainly due to their modulating effects on microbiota that resulted in the change in pattern and process of spoilage in fillets., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Directing the flow of protein traffic is a critical task faced by all cellular organisms. In Gram-negative bacteria, this traffic includes lipoproteins. Lipoproteins are synthesized as precursors in the cytoplasm and receive their acyl modifications upon export across the inner membrane. The third and final acyl chain is added by Lnt, which until recently was thought to be essential in all Gram-negatives. In this report, we show that Acinetobacter species can also tolerate a complete loss-of-function mutation in lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, we show that loss of lnt triggers a global transcriptional response to this added cellular stress. Taken together, our findings provide new insights on and support the growing revisions to the Gram-negative lipoprotein biogenesis paradigm.

Bacterial contact-dependent growth inhibition (CDI) systems are two-partner secretion systems in which toxic CdiA proteins are exported on the outer membrane by cognate transporter CdiB proteins. Upon binding to specific receptors, the C-terminal toxic (CT) domain, detached from CdiA, is delivered to neighbouring cells. Contacts inhibit the growth of not-self-bacteria, lacking immunity proteins co-expressed with CdiA, but promote cooperative behaviours in "self" bacteria, favouring the formation of biofilm structures. The Acinetobacter baylyi ADP1 strain features two CdiA, which differ significantly in size and have different CT domains. Homologous proteins sharing the same CT domains have been identified in A. baumannii. The growth inhibition property of the two A. baylyi CdiA proteins was supported by competition assays between wild-type cells and mutants lacking immunity genes. However, neither protein plays a role in biofilm formation or adherence to epithelial cells, as proved by assays carried out with knockout mutants. Inhibitory and stimulatory properties may be similarly uncoupled in A. baumannii proteins.

In this study, the efficiency improvement of three moving bed biofilm reactors (MBBRs) was investigated by inoculation of activated sludge cells (R1), mixed culture of eight strong phenol-degrading bacteria consisted of Pseudomonas spp. and Acinetobacter spp. (R2) and the combination of both (R3). Biofilm formation ability of eight bacteria was assessed initially using different methods and media. Maximum degradation of phenol, COD, biomass growth and also changes in organic loading shock were used as parameters to measure the performance of reactors. According to the results, all eight strains were determined as enhanced biofilm forming bacteria (EBFB). Under optimum operating conditions, more than 90% of initial COD load of 2795 mg L -1 was reduced at 24 HRT in R3 while this reduction efficiency was observed in concentrations of 1290 mg L -1 and 1935 mg L -1 , in R1 and R2, respectively. When encountering phenol loading shock-twice greater than optimum amount-R1, R2 and R3 managed to return to the steady-state condition within 32, 24 and 18 days, respectively. SEM microscopy and biomass growth measurements confirmed the contribution of more cells to biofilm formation in R3 followed by R2. Additionally, established biofilm in R3 was more resistant to phenol loading shock which can be attributed to the enhancer role of EBFB strains in this reactor. It has been demonstrated that the bacteria with both biofilm-forming and contaminant-degrading abilities are not only able to promote the immobilization of other favorable activated sludge cells in biofilm structure, but also cooperate in contaminant degradation which all consequently lead to improvement of treatment efficiency.

Multidrug efflux systems contribute to antimicrobial resistance and pathogenicity in bacteria. Here, we report the identification and characterization of a transcriptional regulator AcrR controlling the yet uncharacterized multidrug efflux pump, AcrAB in Acinetobacter nosocomialis. In silico analysis revealed that the homologs of AcrR and AcrAB are reported in the genomes of many other bacterial species. We confirmed that the genes encoding the AcrAB efflux pump, acrA and acrB forms a polycistronic operon which is under the control of acrR gene upstream of acrA . Bioinformatic analysis indicated the presence of AcrR binding motif in the promoter region of acrAB operon and the specific binding of AcrR was confirmed by electrophoretic mobility shift assay (EMSA). The EMSA data showed that AcrR binds to -89 bp upstream of the start codon of acrA . The mRNA expression analysis depicted that the expression of acrA and acrB genes are elevated in the deletion mutant compared to that in the wild type confirming that AcrR acts as a repressor of acrAB operon in A. nosocomialis . The deletion of acrR resulted in increased motility, biofilm/pellicle formation and invasion in A. nosocomialis . We further analyzed the role of AcrR in A. nosocomialis pathogenesis in vivo using murine model and it was shown that acrR mutant is highly virulent inducing severe infection in mouse leading to host death. In addition, the intracellular survival rate of acrR mutant was higher compared to that of wild type. Our data demonstrates that AcrR functions as an important regulator of AcrAB efflux pump and is associated with several phenotypes such as motility, biofilm/pellicle formation and pathogenesis in A. nosocomialis .

Plazomicin and comparator agents were tested by using the CLSI reference broth microdilution method against 4,825 clinical isolates collected during 2014 and 2015 in 70 U.S. hospitals as part of the ALERT (Antimicrobial Longitudinal Evaluation and Resistance Trends) program. Plazomicin (MIC 50 /MIC 90 , 0.5/2 μg/ml) inhibited 99.2% of 4,362 Enterobacteriaceae at ≤4 μg/ml. Amikacin, gentamicin, and tobramycin inhibited 98.9%, 90.3%, and 90.3% of these isolates, respectively, by applying CLSI breakpoints. The activities of plazomicin were similar among Enterobacteriaceae species, with MIC 50 values ranging from 0.25 to 1 μg/ml, with the exception of Proteus mirabilis and indole-positive Proteeae that displayed MIC 50 values of 2 μg/ml. For 97 carbapenem-resistant Enterobacteriaceae (CRE), which included 87 isolates carrying bla KPC , plazomicin inhibited all but 1 isolate at ≤2 μg/ml (99.0% and 98.9%, respectively). Amikacin and gentamicin inhibited 64.9% and 56.7% of the CRE isolates at the respective CLSI breakpoints. Plazomicin inhibited 96.5 and 95.5% of the gentamicin-resistant isolates, 96.9 and 96.5% of the tobramycin-resistant isolates, and 64.3 and 90.0% of the amikacin-resistant isolates according to CLSI and EUCAST breakpoints, respectively. The activities of plazomicin against Pseudomonas aeruginosa (MIC 50 /MIC 90 , 4/16 μg/ml) and Acinetobacter species (MIC 50 /MIC 90 , 2/16 μg/ml) isolates were similar. Plazomicin was active against coagulase-negative staphylococci (MIC 50 /MIC 90 , 0.12/0.5 μg/ml) and Staphylococcus aureus (MIC 50 /MIC 90 , 0.5/0.5 μg/ml) but had limited activity against Enterococcus spp. (MIC 50 /MIC 90 , 16/64 μg/ml) and Streptococcus pneumoniae (MIC 50 /MIC 90 , 32/64 μg/ml). Plazomicin activity against the Enterobacteriaceae tested, including CRE and isolates carrying bla KPC from U.S. hospitals, supports the development plan for plazomicin to treat serious infections caused by resistant Enterobacteriaceae in patients with limited treatment options., (Copyright © 2018 American Society for Microbiology.)

Acinetobacter guillouiae SFC 500-1A is an environmental bacterium able to efficiently co-remediate phenol and Cr(VI). To further understand the molecular mechanisms triggered in this strain during the bioremediation process, variations in the proteomic profile after treatment with phenol and phenol plus Cr(VI) were evaluated. The proteomic analysis revealed the induction of the β-ketoadipate pathway for phenol oxidation and the assimilation of degradation products through TCA cycle and glyoxylate shunt. Phenol exposure increased the abundance of proteins associated to energetic processes and ATP synthesis, but it also triggered cellular stress. The lipid bilayer was suggested as a target of phenol toxicity, and changing fatty acids composition seemed to be the bacterial response to protect the membrane integrity. The involvement of two flavoproteins in Cr(VI) reduction to Cr(III) was also proposed. The results suggested the important role of chaperones, antioxidant response and SOS-induced proteins in the ability of the strain to mitigate the damage generated by phenol and Cr(VI). This research contributes to elucidate the mechanisms involved in A. guillouiae SFC 500-1A tolerance and co-remediation of phenol and Cr(VI). Such information may result useful not only to improve its bioremediation efficiency but also to identify putative markers of resistance in environmental bacteria., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Interactions and competition between resident bacteria in food processing environments could affect their ability to survive, grow and persist in microhabitats and niches in the food industry. In this study, the competitive ability of L. monocytogenes strains grown together in separate culture mixes with other L. monocytogenes (L. mono mix), L. innocua (Listeria mix), Gram-negative bacteria (Gram- mix) and with a multigenera mix (Listeria + Gram- mix) was investigated in biofilms on stainless steel and in suspensions at 12 °C. The mixed cultures included resident bacteria from processing surfaces in meat and salmon industry represented by L. monocytogenes (n = 6), L. innocua (n = 5) and Gram-negative bacteria (n = 6; Acinetobacter sp., Pseudomonas fragi, Pseudomonas fluorescens, Serratia liquefaciens, Stenotrophomonas maltophilia). Despite hampered in growth in mixed cultures, L. monocytogenes established in biofilms with counts at day nine between 7.3 and 9.0 log per coupon with the lowest counts in the Listeria + G- mix that was dominated by Pseudomonas. Specific L. innocua inhibited growth of L. monocytogenes strains differently; inhibition that was further enhanced by the background Gram-negative microbiota. In these multispecies and multibacteria cultures, the growth competitive effects lead to the dominance of a strong competitor L. monocytogenes strain that was only slightly inhibited by L. innocua and showed strong competitive abilities in mixed cultures with resident Gram-negative bacteria. The results indicates complex patterns of bacterial interactions and L. monocytogenes inhibition in the multibacteria cultures that only partially depend on cell contact and likely involve various antagonistic and bacterial tolerance mechanisms. The study indicates large variations among L. monocytogenes in their competitiveness under multibacterial culture conditions that should be considered in further studies towards understanding of L. monocytogenes persistence in food processing facilities., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Acinetobacter species are identified as producing surface-active and emulsifying molecules known as bioemulsifiers. Production, characterization and stability of bioemulsifiers produced by Acinetobacter bouvetii UAM25 were studied. A. bouvetii UAM25 grew in three different carbon and energy sources: ethanol, a glycerol-hexadecane mixture and waste cooking oil in an airlift bioreactor, showing that bioemulsifier production was growth associated. The three purified bioemulsifiers were lipo-heteropolysaccharides of high molecular weight (4866 ± 533 and 462 ± 101 kDa). The best carbon source and energy for bioemulsifier production was wasted cooking oil, with a highest emulsifying capacity (76.2 ± 3.5 EU mg -1 ) as compared with ethanol (46.6 ± 7.1 EU mg -1 ) and the glycerol-hexadecane mixture (49.5 ± 4.2 EU mg -1 ). The three bioemulsifiers in our study displayed similar macromolecular structures, regardless of the nature (hydrophobic or hydrophilic) of the carbon and energy source. Bioemulsifiers did not decrease surface tension, but the emulsifying capacity of all of them was retained under extreme variation in salinity (0-50 g NaCl L -1 ), pH (3-10) and temperature (25-121 °C), indicative of remarkable stability. These findings contribute to understanding of the relationship between: production, physical properties, chemical composition and stability of bioemulsifiers for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Purpose: The aim of this study was to examine cohesion, coaggregation, and coculture between bacteria commonly isolated from contact lens cases., Methods: Staphylococcus epidermidis, Staphylococcus haemolyticus, Micrococcus luteus, and Acinetobacter radioresistens (two strains each) isolated from contact lens cases of two asymptomatic wearers were used in this study. In the cohesion assay, bacteria were grown, washed, and examined by incubating lens cases with two different types of bacteria sequentially and assessing the number of adhered cells of each isolate. The ability of isolates to interfere with the growth of other isolates was tested by growing strains in cocultures for 24 hours and determining the numbers of cells of individual strains. For coaggregation, equal proportions of two bacterial suspensions were mixed and allowed to coaggregate for 24 hours. Inhibition of coaggregation was tested by the addition of lactose (0.06 M) or sucrose (0.06 M) or pronase., Results: The initial adhesion of M. luteus or A. radioresistens significantly (P < 0.05) enhanced the subsequent adhesion of the staphylococci. The addition of A. radioresistens in liquid media significantly (P < 0.05) enhanced the growth of staphylococci. S. epidermidis or S. haemolyticus coaggregated with M. luteus or A. radioresistens. The degree of coaggregation varied between 30% and 54%. The highest coaggregation (54% ± 5%) was seen between A. radioresistens 22-1 and S. epidermidis 22-1, isolated from the same lens case. Only lactose or sucrose treatment of staphylococci could partly inhibit coaggregation of some pairs., Conclusions: Coaggregation, cohesion, and growth promotion may facilitate the process of bacterial colonization of contact lens cases.

A toxicity biosensor Acinetobacter baylyi Tox2 was constructed with the host strain A. baylyi ADP1 harboring a new and medium-copy-number plasmid pWH1274&#95;lux, and was applied to detect the cytotoxicity of heavy metal contaminated seawater. The gene cassette luxCDABE was controlled by constitutively expressed promoter P tet on pWH1274&#95;lux and the bioluminescence intensity of the biosensor reduces in proportional to the concentrations of toxic compounds. A. baylyi Tox2 exhibits tolerance to salinity, hence it is applicable to seawater samples. A. baylyi Tox2 and Mugilogobius chulae were exposed to different concentrations of heavy metals (Hg 2+ , Zn 2+ , Cu 2+ , and Cd 2+ ) in artificial seawater for performance comparison and Pearson correlation analysis showed a significant correlation (p < 0.01) between A. baylyi Tox2 toxicity detection and the fish (M. chulae) exposure test. This suggests that the performance of A. baylyi Tox2 is comparable to the conventional fish toxicity test in terms of cytotoxicity detection of heavy metal contaminated seawater. Furthermore, A. baylyi Tox2 was used to evaluate cytotoxicity of field-collected seawater samples. The results indicate that there was a significant correlation between the luminescence inhibition ratio (IR) of A. baylyi Tox2 and heavy metal concentrations detected by ICP-MS in the samples. Two seawater samples, which contained a high concentration of total heavy metals, exhibited stronger cytotoxicity than the samples containing low concentrations of heavy metals. In conclusion, A. baylyi Tox2 can be used as an alternative tool to aquatic animals for the evaluation of the cytotoxicity of heavy metal contamination in the marine environment., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Bacteria inhabit a vast range of biological niches and have evolved diverse mechanisms to cope with environmental stressors. The genus Acinetobacter comprises a complex group of Gram-negative bacteria. Some of these bacteria such as A. baumannii are nosocomial pathogens. They are often resistant to multiple antibiotics and are associated with epidemic outbreaks. A. radioresistens is generally considered to be a commensal bacterium on human skin or an opportunistic pathogen. Interestingly, this species has exceptional resistance to a range of environmental challenges which contributes to its persistence in clinical environment and on human skin. We studied changes in its lipid composition induced by the onset of stationary phase. This strain produced triglycerides (TG) as well as four common phospholipids: phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL) and lysocardiolipin (LCL). It also produced small amounts of acyl-phosphatidylglycerol (APG). As the bacterial growth entered the stationary phase, the lipidome switched from one dominated by PE and PG to another dominated by CL and LCL. Surprisingly, bacteria in the stationary phase produced N-acyl-phosphatidylethanolamine (NAPE) and another rare lipid we tentatively name as 1-phosphatidyl-2-acyl-glycero-3-phosphoethanolamine (PAGPE) based on tandem mass spectrometry. It is possible these tri-acylated lipids play an important role in coping with nutrient depletion.

Resveratrol is among the best-known secondary plant metabolites because of its antioxidant, anti-inflammatory, and anticancer properties. It also is an important allelopathic chemical widely credited with the protection of plants from pathogens. The ecological role of resveratrol in natural habitats is difficult to establish rigorously, because it does not seem to accumulate outside plant tissue. It is likely that bacterial degradation plays a key role in determining the persistence, and thus the ecological role, of resveratrol in soil. Here, we report the isolation of an Acinetobacter species that can use resveratrol as a sole carbon source from the rhizosphere of peanut plants. Both molecular and biochemical techniques indicate that the pathway starts with the conversion of resveratrol to 3,5-dihydroxybenzaldehyde and 4-hydroxybenzaldehyde. The aldehydes are oxidized to substituted benzoates that subsequently enter central metabolism. The gene that encodes the enzyme responsible for the oxidative cleavage of resveratrol was cloned and expressed in Escherichia coli to establish its function. Its physiological role in the resveratrol catabolic pathway was established by knockouts and by the reverse transcription-quantitative PCR (RT-qPCR) demonstration of expression during growth on resveratrol. The results establish the presence and capabilities of resveratrol-degrading bacteria in the rhizosphere of the peanut plants and set the stage for studies to evaluate the role of the bacteria in plant allelopathy. IMPORTANCE In addition to its antioxidant properties, resveratrol is representative of a broad array of allelopathic chemicals produced by plants to inhibit competitors, herbivores, and pathogens. The bacterial degradation of such chemicals in the rhizosphere would reduce the effects of the chemicals. Therefore, it is important to understand the activity and ecological role of bacteria that biodegrade resveratrol near the plants that produce it. This study describes the isolation from the peanut rhizosphere of bacteria that can grow on resveratrol. The characterization of the initial steps in the biodegradation process sets the stage for the investigation of the evolution of the catabolic pathways responsible for the biodegradation of resveratrol and its homologs., (Copyright © 2018 American Society for Microbiology.)

Six genes encoding cold-shock-like proteins, including cspE, are contained within the genome of Acinetobacter oleivorans DR1. All six genes are similar in size as well as amino acid identity, but appear to be differentially regulated under stressful conditions. Four of these genes (cspA, cspB, cspC and cspE) were functionally important during cold shock because of their gradual upregulation during a temperature decrease under our assay conditions. cspE also showed higher expression during alkane degradation and antibiotic exposure. The transcriptional start site of the cspE gene was determined using 5' rapid amplification of complementary DNA ends. Next, promoter analysis using numerous constructed gfp reporter strains containing deleted fragments of cspE upstream regions identified possible 5' untranslated region (UTR) cis-DNA elements that could be involved in modulating cspE expression. Deletion of cspE led to a growth defect and enhanced biofilm formation, but only at a low temperature. Collectively, our findings show the importance of CspE during cold shock, dynamic regulation of cspE expression under various stressful conditions and a possible 5'-UTR cis-DNA element for regulation of cspE expression. These data provide molecular insight into cspE gene expression during cold-shock adaptation in soil bacteria., (Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)