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We previously demonstrated that Alcaligenes-derived lipid A (ALA), which is produced from an intestinal lymphoid tissue-resident commensal bacterium, is an effective adjuvant for inducing antigen-specific immune responses. To understand the immunologic characteristics of ALA as a vaccine adjuvant, we here compared the adjuvant activity of ALA with that of a licensed adjuvant (monophosphoryl lipid A, MPLA) in mice. Although the adjuvant activity of ALA was only slightly greater than that of MPLA for subcutaneous immunization, ALA induced significantly greater IgA antibody production than did MPLA during nasal immunization. Regarding the underlying mechanism, ALA increased and activated CD11b+ CD103- CD11c+ dendritic cells in the nasal tissue by stimulating chemokine responses. These findings revealed the superiority of ALA as a mucosal adjuvant due to the unique immunologic functions of ALA in nasal tissue.

Direct ammonia oxidation (Dirammox) might be of great significance to advance the innovation of biological nitrogen removal process in wastewater treatment systems. However, it remains unknown whether Dirammox bacteria can be selectively enriched in activated sludge. In this study, a lab-scale bioreactor was established and operated for 2 months to treat synthetic wastewater with hydroxylamine as a selection pressure. Three Dirammox strains (Alcaligenes aquatilis SDU_AA1, Alcaligenes aquatilis SDU_AA2, and Alcaligenes sp. SDU_A2) were isolated from the activated sludge, and their capability to perform Dirammox process was confirmed. Although these three Dirammox bacteria were undetectable in the seed sludge (0%), their relative abundances rapidly increased after a month of operation, reaching 12.65%, 0.69%, and 0.69% for SDU_A2, SDU_AA1, and SDU_AA2, respectively. Among them, the most dominant Dirammox (SDU_A2) exhibited higher nitrogen removal rate (32.35%) than the other two strains (13.57% of SDU_AA1 and 14.52% of SDU_AA2). Comparative genomic analysis demonstrated that the most dominant Dirammox bacterium (SDU_A2) possesses fewer complete metabolic modules compared to the other two less abundant Alcaligenes strains. Our findings expanded the understanding of the application of Dirammox bacteria as key functional microorganisms in a novel biological nitrogen and carbon removal process if they could be well stabilized. Key points: • Dirammox-dominated microbial community was enriched in activated sludge bioreactor. • The addition of hydroxylamine played a role in Dirammox enrichment. • Three Dirammox bacterial strains, including one novel species, were isolated. [ABSTRACT FROM AUTHOR]

We previously demonstrated that Alcaligenes -derived lipid A (ALA), which is produced from an intestinal lymphoid tissue-resident commensal bacterium, is an effective adjuvant for inducing antigen-specific immune responses. To understand the immunologic characteristics of ALA as a vaccine adjuvant, we here compared the adjuvant activity of ALA with that of a licensed adjuvant (monophosphoryl lipid A, MPLA) in mice. Although the adjuvant activity of ALA was only slightly greater than that of MPLA for subcutaneous immunization, ALA induced significantly greater IgA antibody production than did MPLA during nasal immunization. Regarding the underlying mechanism, ALA increased and activated CD11b+ CD103− CD11c+ dendritic cells in the nasal tissue by stimulating chemokine responses. These findings revealed the superiority of ALA as a mucosal adjuvant due to the unique immunologic functions of ALA in nasal tissue. [ABSTRACT FROM AUTHOR]

We previously identified Alcaligenes spp. as a commensal bacterium that resides in lymphoid tissues, including Peyers patches. We found that Alcaligenes-derived lipopolysaccharide acted as a weak agonist of Toll-like receptor four due to the unique structure of lipid A, which lies in the core of lipopolysaccharide. This feature allowed the use of chemically synthesized Alcaligenes lipid A as a safe synthetic vaccine adjuvant that induces Th17 polarization to enhance systemic IgG and respiratory IgA responses to T-cell-dependent antigens (e.g., ovalbumin and pneumococcal surface protein A) without excessive inflammation. Here, we examined the adjuvant activity of Alcaligenes lipid A on a Haemophilus influenzae B conjugate vaccine that contains capsular polysaccharide polyribosyl ribitol phosphate (PRP), a T-cell-independent antigen, conjugated with the T-cell-dependent tetanus toxoid (TT) antigen (i.e., PRP-TT). When mice were subcutaneously immunized with PRP alone or mixed with TT, Alcaligenes lipid A did not affect PRP-specific IgG production. In contrast, PRP-specific serum IgG responses were enhanced when mice were immunized with PRP-TT, but these responses were impaired in similarly immunized T-cell-deficient nude mice. Furthermore, TT-specific-but not PRP-specific-T-cell activation occurred in mice immunized with PRP-TT together with Alcaligenes lipid A. In addition, coculture with Alcaligenes lipid A promoted significant proliferation of and enhanced antibody production by B cells. Together, these findings suggest that Alcaligenes lipid A exerts an adjuvant activity on thymus-independent Hib polysaccharide antigen in the presence of a T-cell-dependent conjugate carrier antigen.

Among the major constraints for the production of economic crops, such as maize, is salinity. Plenty of research has suggested the use of various strains of plant growth-promoting rhizobacteria (PGPR) as a sustainable approach to improve plant tolerance to salinity. Nonetheless, the exploration of the rhizosphere in Egyptian agricultural lands with salt affected soil remains incomplete. In this research, two newly isolated local bacterial species were finally selected and identified as Alcaligenes sp. strains. E1 (BS-45) and E2 (BS-57). IAA production by both isolates was confirmed by TLC. Several bioactive metabolites were identified in Alcaligenes sp. E1 and E2 by gas chromatography-mass spectroscopy (GC-MS). These include 9,12,15-octadecatrienoic acid, 2,3-bis [(trimethylsilyl)oxy] propyl ester, (z,z,z), 2 (1H)-Naphthalenone, octahydro-1-methyl-1-(2-propenyl)-, (1à,4aá,8aà), dodecane and isopulegol which have a defensive role against biotic and abiotic stress of the plant. Interestingly, the selected bacteria Alcaligenes sp. E1 and E2 significantly improve the overall maize growth attributes, antioxidant scavenging activities and photosynthetic pigments in maize plants grown under salt stress (150 mM NaCl) compared to the control plants as analyzed by greenhouse experiment. Therefore, this study recommends the Alcaligenes sp. strains (E1 and E2) to alleviate the negative impact of salinity on the growth and development of maize seedlings. • Two potent native soil bacterial isolates were selected based on plant growth promoting and antifungal activities. • The selected isolates were identified as Alcaligense sp. E1 and Alac ligense sp. E2. • The bacterial cultural and nutritional conditions for IAA production were optimized. • The prospective bioactive compounds have been detected and identified by gas chromatography-mass spectroscopy. • Significant improvement in growth of maize seedling under high-salt stress were recorded compared to untreated control. [ABSTRACT FROM AUTHOR]

Hydrolyzed polyacrylamide (HPAM) is posing serious threats to ecosystems. However, biodegradation is an effective method to remove HPAM owing to its low cost and environmental friendliness. In this study, Alcaligenes faecalis EPDB-5 was isolated as a highly efficient HPAM degrading strain from sludge contaminated with polymerized produced water from Daqing oilfield. Under the optimal conditions, the strain EPDB-5 demonstrated an impressive HPAM degradation rate of 86.05%, the total nitrogen (TN) removal of 71.96% and chemical oxygen demand (COD) removal of 67.98%. Meanwhile, it can maintain a stable degradation rate higher than 75% under different pH and temperature conditions. 27 genes that play a key role in HPAM degradation were annotated by metagenomics sequencing. The key genes were involved in multiple KEGG pathways, including biofilm formation, biosynthesis secondary metabolites, and metabolic pathways. SEM, GPC, and FTIR analyses revealed that the structure of HPAM after biodegradation showed pores, a significant decrease in molecular weight, -NH 2 detachment, and carbon chain breakage. Particularly, we propose a possible mechanism of biofilm formation - HPAM degradation - biofilm disappearance and reorganization. Moreover, the degradation rate of strain EPDB-5 on real wastewater containing HPAM was 29.97% in only three days. This work expands our knowledge boundary about the HPAM degradation mechanism at the functional gene level, and supports the potential of strain EPDB-5 as a novel auxiliary microbial resource for the practical application of HPAM., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Mutai Bao reports financial support was provided by SNF(China) Flocculants Ltd. Mutai Bao has patent #ZL 2024 1 0223575.3 licensed to Ocean university of China, SNF (China) Flocculants Ltd. 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. If there are other authors, they 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.)

Nitrogen cycle is an essential process for environmental health. Dirammox (dir ect amm onia ox idation), encoded by the dnfT1RT2ABCD cluster, was a novel pathway for microbial N2 production defined in Alcaligenes ammonioxydans HO-1. Here, a copy of the cluster dnfT1RT2ABCD as a whole was proved to have existed and very conserved in all Alcaligenes genomes. Phylogenetic analyses based on 16S rRNA gene sequences and amino acid sequences of DnfAs, together with G + C content data, revealed that dnf cluster was evolved associated with the members of the genus Alcaligenes. Under 20% O2 conditions, 14 of 16 Alcaligenes strains showed Dirammox activity, which seemed likely taxon-related. However, the in vitro activities of DnfAs catalyzing the direct oxidation of hydroxylamine to N2 were not taxon-related but depended on the contents of Fe and Mn ions. The results indicated that DnfA is necessary but not sufficient for Dirammox activity. The fact that members of the genus Alcaligenes are widely distributed in various environments, including soil, water bodies (both freshwater and seawater), sediments, activated sludge, and animal–plant-associated environments, strongly suggests that Dirammox is important to the nitrogen cycle. In addition, Alcaligenes species are also commonly found in wastewater treatment plants, suggesting that they might be valuable resources for wastewater treatment. [ABSTRACT FROM AUTHOR]

The use of biological molecules to control pollutants, especially heavy metals that pollute our atmosphere, is gaining traction. In this study, simulation and optimization of process parameters using one-factor-at-a-time and response surface methodology (RSM) were employed to assess conditions for heavy metal tolerant bacteria isolated from local mining area employed in biosorption of heavy metals. Morphological, biochemical, and molecular characteristics of the isolate was determined using standard procedures. The agar plate method was used to determine heavy metal tolerance of the bacterial isolate. The effect of factors affecting biosorption of heavy metals was assessed using one-factor-at-a-time and response surface methodology respectively. The Gram-negative Alcaligenes faecalis strain UBI isolated in this study was capable of tolerating 27.0ppm of Pb2+. Optimum temperature and pH recorded were 35°C and 5 respectively. Similarly, optimum metal concentration indicated 2.5ppm with 12 hours contact time and at 7% of Inocula size (v/v) respectively. Simulation by RSM showed that the model is significant (p =.0013). The statistical accuracy of the model was elaborated by the non-significant lack of fit. The R2 (0.98) value highlights a perfect model likewise the low value of the coefficient of variance (CV = 3.09%). This study supports the idea of using bacteria as a panacea to heavy metal pollution under-regulated process parameters. [ABSTRACT FROM AUTHOR]

Simple Summary: Isoprene, a volatile hydrocarbon, is the second most abundantly produced climate-active gas, with largely indirect detrimental impacts, such as extending the residence time of the greenhouse gas methane. Isoprene is mainly emitted by plants and can be consumed by a range of microbes inhabiting diverse environments, including soil. Here, the ability of soil bacteria to degrade isoprene was investigated. Soil samples were taken from beneath wild Himalayan cherry trees in a tropical restored forest area, and an Alcaligenes sp. (strain 13f) was isolated. This isolate used isoprene as a sole source of carbon and energy (32.6% of isoprene was consumed in 18 days). A surprising finding from the genome analysis of Alcaligenes sp. strain 13f was that the well-characterised genes and genetic organisation typical of other isoprene-degrading bacteria were not observed. Thus, we propose that this strain uses a different metabolic pathway for isoprene degradation. Isoprene is a climate-active biogenic volatile organic compound (BVOC), emitted into the atmosphere in abundance, mainly from terrestrial plants. Soil is an important sink for isoprene due to its consumption by microbes. In this study, we report the ability of a soil bacterium to degrade isoprene. Strain 13f was isolated from soil beneath wild Himalayan cherry trees in a tropical restored forest. Based on phylogenomic analysis and an Average Nucleotide Identity score of >95%, it most probably belongs to the species Alcaligenes faecalis. Isoprene degradation by Alcaligenes sp. strain 13f was measured by using gas chromatography. When isoprene was supplied as the sole carbon and energy source at the concentration of 7.2 × 105 ppbv and 7.2 × 106 ppbv, 32.6% and 19.6% of isoprene was consumed after 18 days, respectively. Genome analysis of Alcaligenes sp. strain 13f revealed that the genes that are typically found as part of the isoprene monooxygenase gene cluster in other isoprene-degrading bacteria were absent. This discovery suggests that there may be alternative pathways for isoprene metabolism. [ABSTRACT FROM AUTHOR]

Background and Aim: Alcaligenes ssp. is a non-fermentative Gram-negative bacillus, which causes nosocomial infections, including urinary tract infections, pneumonia, sepsis, and may be confused with Pseudomonas aeruginosa. Alcaligenes infections usually are not well identified and due to possible errors and similarities with Pseudomonas, their diagnosis with phenotypic tests is not sufficient. In this case, molecular methods seem to be more effective. We aimed to investigate the real presence of clinical isolates of Alcaligenes xylosoxidans and Alcaligenes faecalis by phenotypical, and genetic methods and their antibiotic susceptibility. Materials and Methods: From September 2019 to March 2020, we analyzed 36 clinical isolates from a Sina hospital in Hamadan, Iran, which have been identified as Alcaligenes in the hospital's microbiology lab, by routine phenotypicall methods. Using the PCR method and tracking AX and 77F-r genes, we identified A. xylosoxidans and A. faecalis respectively; the antibiotic resistance of each isolate was determined by the disc diffusion method. Results: Of 36 samples of phenotypically identified Alcaligenes, only 13 (36.11%) were confirmed as A. xylosoxidans and 3 (8.33%) as A. faecalis by PCR test. Among A. xylosoxidans isolates, the highest susceptibility (92.3%) was against cephalosporin and the highest resistance (76.92%) was against ciprofloxacin. Among A. faecalis isolates, the most susceptibility (100%) was against ceftazidime, piperacillin/tazobactam, imipenem, meropenem, and cefepime, and the most resistance (66.66%) was against gentamicin and ceftriaxone. Conclusion: Regarding the importance of accurate diagnosis of Alcaligenes in combating nosocomial infections, it seems with phenotypic and biochemical tests, there is a possibility of error in their diagnosis; so using the PCR method, each species can be determined more accurately. [ABSTRACT FROM AUTHOR]

Nitrogen cycle is an essential process for environmental health. Dirammox (direct ammonia oxidation), encoded by the dnfT1RT2ABCD cluster, was a novel pathway for microbial N2 production defined in Alcaligenes ammonioxydans HO-1. Here, a copy of the cluster dnfT1RT2ABCD as a whole was proved to have existed and very conserved in all Alcaligenes genomes. Phylogenetic analyses based on 16S rRNA gene sequences and amino acid sequences of DnfAs, together with G + C content data, revealed that dnf cluster was evolved associated with the members of the genus Alcaligenes. Under 20% O2 conditions, 14 of 16 Alcaligenes strains showed Dirammox activity, which seemed likely taxon-related. However, the in vitro activities of DnfAs catalyzing the direct oxidation of hydroxylamine to N2 were not taxon-related but depended on the contents of Fe and Mn ions. The results indicated that DnfA is necessary but not sufficient for Dirammox activity. The fact that members of the genus Alcaligenes are widely distributed in various environments, including soil, water bodies (both freshwater and seawater), sediments, activated sludge, and animal–plant-associated environments, strongly suggests that Dirammox is important to the nitrogen cycle. In addition, Alcaligenes species are also commonly found in wastewater treatment plants, suggesting that they might be valuable resources for wastewater treatment.

Background: Clostridium perfringens and Shiga toxin (Stx)-producing Escherichia coli (STEC) are common causes of food poisoning. We previously demonstrated the efficacy of Stx2B-C-CPE, a fusion protein of the C-terminal region of C. perfringens enterotoxin (C-CPE) and Shiga toxin 2 B subunit (Stx2B), as a bivalent vaccine against C. perfringens and STEC infections. Methods: Here, we applied an E. coli expression system and Triton X-114 phase separation to prepare tag- and endotoxin-free Stx2B-C-CPE for use in vaccine formulations. Results: As we anticipated, endotoxin removal from the purified antigen reduced both Stx2B- and C-CPE-specific IgG antibody responses in subcutaneously immunized mice, suggesting that endotoxin contamination influences the immunological assessment of Stx2B-C-CPE. However, the combined use of aluminum and Alcaligenes lipid A adjuvants improved IgG antibody responses to the injected antigen, thus indicating the suitability of purified Stx2B-C-CPE for vaccine formulation. Conclusions: Our current findings provide important knowledge regarding the design of an effective commercial Stx2B-C-CPE vaccine.

Bacterial lipase holds an important role as a new source for many industrial catalysts. The investigation and understanding of the lipase-encoding gene become apparent as the key step for generating high-quality lipase as biocatalyst for many chemical reactions. In this study, bacterial lipase from Alcaligenes sp. JG3 was produced via overexpression gene method. This specific lipase was successfully overexpressed using pQE-30 vector and E. coli M15[pREP4] as host, producing His-tagged protein sized 46 kDa and was able to hydrolyze triacylglycerol from olive oil with the calculated unit activity and specific activity of 0.012 U and 1.175 U/mg respectively. The in silico investigation towards lipase JG3 revealed that it was categorized as ABC transporter protein as opposed to the conventional hydrolase family. Lastly, amino acid sequences SGSGKTT from lipase JG3 was highly conserved sequences and was predicted as the ATP-binding site but the catalytic triad of serine, histidine, and aspartate has not been solved yet.

At present, the all-iron redox flow batteries (RFBs) have greater application potential due to high accessibility of electrolytes compared to traditional RFBs. Meanwhile, although electroactive bacteria can accelerate the electrons transfer, their potential to improve the performance of RFBs has been overlooked. Previously, we had confirmed that ferrous-oxidizing bacteria (FeOB) could enhance the performance of an all-iron RFB, therefore we conducted several batch experiments and chronopotentiometry experiments by using the ferric-reducing bacteria (FeRB) or mixed culture (FeOB and FeRB) to demonstrate whether they have the same or stronger effects on Fe 3+ -DTPA/Na 4 [Fe(CN) 6 ] RFB. The results showed that the experimental reactors could achieve higher charging current density and initial cathodic potential during constant voltage charging process. The electrochemical impedance spectroscopy data and cyclic voltammetry curves demonstrated that the polarization impedance increased slower and reduction peak potential of experimental groups also emerged a positive shift compared to CK. According to chronopotentiometry experiments results, the microbes could function at maximum 0.3 M, 12 mA/cm 2 , and also improved the charging specific capacity. Combined the SEM pictures and microbial composition analysis, the main functional electroactive FeRB were Alcaligenes, Corynebacterium and Bacillus, which indicated to have important potential in improving the performance of RFBs., 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 B.V. All rights reserved.)

We previously identified Alcaligenes spp. as a commensal bacterium that resides in lymphoid tissues, including Peyer’s patches. We found that Alcaligenes-derived lipopolysaccharide acted as a weak agonist of Toll-like receptor four due to the unique structure of lipid A, which lies in the core of lipopolysaccharide. This feature allowed the use of chemically synthesized Alcaligenes lipid A as a safe synthetic vaccine adjuvant that induces Th17 polarization to enhance systemic IgG and respiratory IgA responses to T-cell–dependent antigens (e.g., ovalbumin and pneumococcal surface protein A) without excessive inflammation. Here, we examined the adjuvant activity of Alcaligenes lipid A on a Haemophilus influenzae B conjugate vaccine that contains capsular polysaccharide polyribosyl ribitol phosphate (PRP), a T-cell–independent antigen, conjugated with the T-cell–dependent tetanus toxoid (TT) antigen (i.e., PRP-TT). When mice were subcutaneously immunized with PRP alone or mixed with TT, Alcaligenes lipid A did not affect PRP-specific IgG production. In contrast, PRP-specific serum IgG responses were enhanced when mice were immunized with PRP-TT, but these responses were impaired in similarly immunized T-cell—deficient nude mice. Furthermore, TT-specific—but not PRP-specific—T-cell activation occurred in mice immunized with PRP-TT together with Alcaligenes lipid A. In addition, coculture with Alcaligenes lipid A promoted significant proliferation of and enhanced antibody production by B cells. Together, these findings suggest that Alcaligenes lipid A exerts an adjuvant activity on thymus-independent Hib polysaccharide antigen in the presence of a T-cell–dependent conjugate carrier antigen.

Bacterial lipases have significant potential to be used as the biocatalyst for many chemical reactions. In this study, a novel gene encoding lipase was isolated from an Alcaligenes sp. JG3. A pair of designed primer has successfully isolated 1 kb (LipJG3) that shares 98% identity towards lipase from Alcaligenes faecalis during sequence analysis. By using in silico tools, LipJG3 was related to the transporter protein sequences. Three highly conserved regions consisting of EASGSKT, VILLD, and LSGGQQQRVAIA were found. These regions were known as ATP-binding signature at Walker-A and Walker-B motifs and the S signature of ABC transporter family respectively. In addition, the 3-D structure of LipJG3 has been suggested but the role of the catalytic triad residues have been not fully understood.

Isoprene is a climate-active biogenic volatile organic compound (BVOC), emitted into the atmosphere in abundance, mainly from terrestrial plants. Soil is an important sink for isoprene due to its consumption by microbes. In this study, we report the ability of a soil bacterium to degrade isoprene. Strain 13f was isolated from soil beneath wild Himalayan cherry trees in a tropical restored forest. Based on phylogenomic analysis and an Average Nucleotide Identity score of >95%, it most probably belongs to the species Alcaligenes faecalis. Isoprene degradation by Alcaligenes sp. strain 13f was measured by using gas chromatography. When isoprene was supplied as the sole carbon and energy source at the concentration of 7.2 × 105 ppbv and 7.2 × 106 ppbv, 32.6% and 19.6% of isoprene was consumed after 18 days, respectively. Genome analysis of Alcaligenes sp. strain 13f revealed that the genes that are typically found as part of the isoprene monooxygenase gene cluster in other isoprene-degrading bacteria were absent. This discovery suggests that there may be alternative pathways for isoprene metabolism.

The use of microorganisms for bioremediation of polychlorinated biphenyls (PCBs) is reported. Three bacterial species namely Alcaligenes sp., Tistrella sp. and Bacillus amyloliquefaciens, isolated from paint contaminated sites, have been found to degrade the PCB congeners from soil individually under laboratory conditions. The three bacterial species dehalogenated effectively the lower chlorinated PCB congeners. In a PCB mixture in soil, the bacteria dissipated 31.0-34.4 per cent of di-, 22.3-28.8 per cent of tri-, 10.1-19.6 per cent of tetra-, 5.8-8.1 per cent of hexa- and 3.8-5.4 per cent of hepta-chlorinated congeners in 30 d. The findings suggest that PCB dechlorination in the soil system could be linked to aerobic microbial biodegradation. The work will be helpful in achieving a sustainable natural attenuation of xenobiotics in the environment. [ABSTRACT FROM AUTHOR]

Vaccination has contributed greatly to the control of infectious diseases; however, regional and individual differences are occasionally observed in the efficacy of vaccination. As one explanation for these differences, much attention has focused on the intestinal environment constructed by the interaction of diet and the gut microbiota. The intestinal environment has several physiological effects on the host immune system, both locally and systemically, and consequently influences the efficacy of vaccination. In this review, we discuss the impact of the gut microbiota and dietary nutrients on systemic and oral vaccination as well as their applications in various strategies for immunoregulation, including use as vaccine adjuvants. This information could contribute to establishing methods of personalized vaccination that would optimize host immunity by changing the gut environment to maximize vaccine effects. [ABSTRACT FROM AUTHOR]

Stenotrophomonas maltophilia, Burkholderia cepacia complex, Elizabethkingia spp., Chryseobacterium spp., Achromobacter spp., and Alcaligenes spp. are less‐common non–lactose‐fermenting bacteria that have emerged as important opportunistic pathogens. Patients at the highest risk for these infections include the immunocompromised, those with cystic fibrosis, and the critically ill. These opportunistic pathogens are frequently drug resistant through the expression of β‐lactamases, multidrug efflux pumps, aminoglycoside‐modifying enzymes, and target site alterations discussed in detail throughout this review. As a result, treatment is extremely challenging. For each pathogen, this review will examine the epidemiology, mechanisms of resistance, and in vitro and in vivo data including that for novel β‐lactam/β‐lactamase inhibitors and cefiderocol. Treatment recommendations are provided based on the available literature. [ABSTRACT FROM AUTHOR]

In the present study halotolerant bacteria were isolated from saline soil (EC ~ 11.9). Based on salt tolerance and plant growth promoting characteristics isolate AF7 was selected for further study. It was identified as Alcaligenes sp. on the basis of protein profiling and 16S rRNA sequence homology. Interestingly, AF7 showed diverse PGP characters at different salinity levels. While phosphate solubilization activity was expressed up to 300 mM NaCl, siderophore production was shown up to 700 mM, zinc solubilization up to 1000 mM and indole acetic acid (IAA), gibberellic acid (GA) and exopolysaccharides (EPS) production were depicted till 1400 mM. Correlative and regression analysis suggested positive relation between IAA, GA, EPS, siderophore production and zinc solubilization capability of AF7 and salinity up to 300 mM NaCl. EPS was found to be the most significant response and there was 263% increment in presence of 300 mM NaCl when compared to non-saline control. Analysis also showed that while growth promoting attributes were significant up to a threshold salinity level, further increasing the stress deviates the mechanism towards survival involving proline, antioxidant and hydroxyl scavenging activities. Combination of halotolerant AF7 and EPS showed more than twofold increase in the vegetative growth parameters of rice at ~ 170 mM NaCl (EC 9 dS/m). The study shows the mechanisms/metabolites of the plant growth promoting bacterium (PGPB) AF7 prominently involved during the salinity stress. Study also proves that novel bioformulations can be developed by integrative use of EPS and salt tolerant-PGPB which can be effective for saline soils. [ABSTRACT FROM AUTHOR]

Alcaligenes aquatilis QD168 is a marine, aromatic hydrocarbon-degrading bacterium, isolated from an oil-polluted sediment of Quintero Bay, an industrial-coastal zone that has been chronically impacted by diverse pollutants. The aims of this study were to characterize the phylogenomic positions of Alcaligenes spp. and to characterize the genetic determinants and the physiological response of A. aquatilis QD168 to model environmental stressors (benzene, oxidizing agents, and salt). Phylogenomic analyses, using 35 housekeeping genes, clustered A. aquatilis QD168 with four other strains of Alcaligenes spp. (A. aquatilis BU33N, A. faecalis JQ135, A. faecalis UBA3227, and A. faecalis UBA7629). Genomic sequence analyses of A. aquatilis QD168 with 25 Alcaligenes spp., using ANIb, indicated that A. aquatilis BU33N is the closest related strain, with 96.8% ANIb similarity. Strain QD168 harbors 95 genes encoding proteins of seven central catabolic pathways, as well as sixteen peripheral catabolic pathways/reactions for aromatic compounds. A. aquatilis QD168 was able to grow on 3-hydroxybenzoate, 4-hydroxybenzoate, benzoate, benzene, 3-hydroxycinnamate, cinnamate, anthranilate, benzamide, 4-aminobenzoate, nicotinate, toluene, biphenyl and tryptophan, as sole carbon or nitrogen source. Benzene degradation was further analyzed by growth, metabolite identification and gene expression analyses. Benzene strongly induced the expression of the genes encoding phenol hydroxylase (dmpP) and catechol 1,2-dioxygenase (catA). Additionally, 30 genes encoding transcriptional regulators, scavenging enzymes, oxidative damage repair systems and isozymes involved in oxidative stress response were identified. Oxidative stress response of strain QD168 to hydrogen peroxide and paraquat was characterized, demonstrating that A. aquatilis QD168 is notably more resistant to paraquat than to H2O2. Genetic determinants (47 genes) for osmoprotective responses were identified, correlating with observed high halotolerance by strain QD168. The physiological adaptation of A. aquatilis QD168 to environmental stressors such as pollutants, oxidative stress and salinity may be exploited for bioremediation of oil-polluted saline sites.

Alcaligenes aquatilis QD168 is a marine, aromatic hydrocarbon-degrading bacterium, isolated from an oil-polluted sediment of Quintero Bay, an industrial-coastal zone that has been chronically impacted by diverse pollutants. The aims of this study were to characterize the phylogenomic positions of Alcaligenes spp. and to characterize the genetic determinants and the physiological response of A. aquatilis QD168 to model environmental stressors (benzene, oxidizing agents, and salt). Phylogenomic analyses, using 35 housekeeping genes, clustered A. aquatilis QD168 with four other strains of Alcaligenes spp. (A. aquatilis BU33N, A. faecalis JQ135, A. faecalis UBA3227, and A. faecalis UBA7629). Genomic sequence analyses of A. aquatilis QD168 with 25 Alcaligenes spp., using ANIb, indicated that A. aquatilis BU33N is the closest related strain, with 96.8% ANIb similarity. Strain QD168 harbors 95 genes encoding proteins of seven central catabolic pathways, as well as sixteen peripheral catabolic pathways/reactions for aromatic compounds. A. aquatilis QD168 was able to grow on 3-hydroxybenzoate, 4-hydroxybenzoate, benzoate, benzene, 3-hydroxycinnamate, cinnamate, anthranilate, benzamide, 4-aminobenzoate, nicotinate, toluene, biphenyl and tryptophan, as sole carbon or nitrogen source. Benzene degradation was further analyzed by growth, metabolite identification and gene expression analyses. Benzene strongly induced the expression of the genes encoding phenol hydroxylase (dmpP) and catechol 1,2-dioxygenase (catA). Additionally, 30 genes encoding transcriptional regulators, scavenging enzymes, oxidative damage repair systems and isozymes involved in oxidative stress response were identified. Oxidative stress response of strain QD168 to hydrogen peroxide and paraquat was characterized, demonstrating that A. aquatilis QD168 is notably more resistant to paraquat than to H2O2. Genetic determinants (47 genes) for osmoprotective responses were identified, correlating with observed high halotolerance by strain QD168. The physiological adaptation of A. aquatilis QD168 to environmental stressors such as pollutants, oxidative stress and salinity may be exploited for bioremediation of oil-polluted saline sites. [ABSTRACT FROM AUTHOR]

Pali city in Rajasthan has been a major environmental concern in the terms of extensive water pollution caused by the textile industries. The textile effluents are characterized by remarkably strong colour, high pH, BOD and COD. The major culprits are the direct diazo dyes and one such dye is Direct Red 28. To develop an effective bioprocess for dye degradation, bacteria were screened from different stages of the common effluent treatment plant situated in Mandia Road, Pali. The most potential bacteria was an isolate from aeration tank and characterized as Alcaligenes sp. TEX S6 by 16S rDNA sequencing. The dye removal efficacy of the strain was expressed as a reduction in absorbance maxima of the dye. The strain removed the dye (0.15 g/L) up to 86% within 48 hours of static incubation utilizing fructose and peptone at 37ºC and pH 7. The inoculum concentration had no effect on the decolourisation process. A significant increase in bioefficacy of the strain was observed with respect to abiotic control. TLC chromatogram and FTIR spectra of the pure dye compound and the decolourised dye was suggestive of enzymatic degradation in accordance with biodecolourisation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A cyanide removal system was constructed with a synergic effect of adsorption and biodegradation. • The PUF-immobilized cell system showed higher removal efficiency and stability. • removal capacity of the PUF-immobilized cell system could reach 1200 mg CN−/L. • The enhancement of the SAB immobilized cell system was discussed. Abstract A high efficiency and stability polyurethane-foam (PUF)-immobilized cell system was constructed to remove cyanide based on simultaneous adsorption and biodegradation (SAB). The performance of the PUF-immobilized system was evaluated by comparison with the freely suspended cell system. The SAB system exhibited more effective and robust, and could still remain degradation activity even at 40 °C or pH 11.0. The SAB system completely removed 500 mg CN−/L within 8 h at 30 °C, pH 8.0, and 120 rpm, whereas 12 h were required for the free cells system. Moreover, the SAB system showed apparent superiority in removing higher concentration cyanide up to 1200 mg CN−/L. A continuously stirred tank bioreactor (CSTR) was successfully designed and steadily operated with approximately 85% of the total average removal efficiency for 52 days at an influent cyanide concentration of 100–200 mg/L, which demonstrated a favorable reliability. Cyanide removal process could be well described using a pseudo first-order model, and the higher apparent rate constants (k) of the immobilized cells showed the synergic effect of adsorption and biodegradation significantly enhanced cyanide removal. Preliminarily, it was found that the foam characteristic might play a not negligible role on the cyanide-degrading enzyme expression of strain DN25 in the SAB system. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrates (PHBs) are energy reserves synthesized by different micro-organisms such as Alcaligenes, Pseudomonas, Staphylococcus, Algae, in excess of carbon and limitation of nutrients like nitrogen. These biopolymers are suitable alternate to synthetic carbon-based polymers. However, the high production cost limits their commercialization. The aim of this study was thus, focused on optimization of culture condition for maximum PHB production in an attempt to reduce the production cost. The micro-organisms for this purpose were isolated from 4 different soil samples and screened for PHB production. Culture conditions for these organisms were optimized by changing the parameters, viz., incubation time, pH, carbon source and NaCl concentration. Thus, optimized culture condition was used to culture the isolates for extraction of PHB and its analysis. The extracted compounds on FTIR-analysis gave characteristic C=O peak of PHB, thus, confirming the seven isolates to be PHB producers. Results for optimized parameters for the isolated PHB positive species showed that synthesis of PHB was maximum at 48 hours i.e. during the early stages of stationary phase. However, different isolates favored different culture conditions. Highest PHB accumulation and growth of isolates were seen at pH 7 and 9. Similarly, it was observed that glucose was favored by 4 isolates and sucrose was favored by 3 isolates. Interestingly, NaCl concentration did not cause significant effect on neither the bacterial growth nor the PHB production. During the extraction of PHB from the optimized culture conditions, extraction of PHB from broth gave significant yield than that from agar. A good PHB yield from broth amounting to 36.41% and 34.59% was observed for Bacillus pasteurii and Micrococcus luteus respectively, showing a potential for their exploitation in industrial PHB production. At optimized conditions, 7 isolates exhibited significant PHB yields, thus showing a potential for further exploitation. [ABSTRACT FROM AUTHOR]

A 38-year-old male presented with pain and redness in his left eye. He had a history of wearing contact lenses. His ophthalmic examination revealed a large corneal ulcer with surrounding infiltrate. Cultures were isolated from the contact lenses, lens solutions, storage cases, and conjunctivae of both eyes and also corneal scrapings of the left eye. Fortified vancomycin and amikacin drops were started hourly. Culture results of conjunctivae of each eye and left cornea were positive for Pseudomonas aeruginosa; cultures from the contact lenses, lens solution and storage case of both eyes revealed Pseudomonas aeruginosa and Alcaligenes xylosoxidans. Polymerase chain reaction of the corneal scraping was positive for Acanthameoba. The topical antibiotics were changed with ones that both bacteria were sensitive to and anti-amoebic therapy was added. The patient had two recurrences following initial presentation despite intensive therapy. Keratitis occurred due to multiple pathogens; the relapsing course despite adequate therapy is potentially associated with this polymicrobial etiology.

Utilization of glycerol by lipase producing bacteria offers great benefits for fat and oil waste degradation and waterwaste treatment. Nevertheless, there have been lack of reports about the availability of non-pathogenic, lipase producing bacteria, which could naturally degrade glycerol produced from the lipolysis process by lipase. This study reported a newly identified species of rhizobacteria, Alcaligenes javaensis JG3, which is not only able to produce high level of lipase, but also able to degrade glycerol molecules. Identification of strain JG3 was carried out using SEM (Scanning Electron Microscope), BD Phoenix 100 Automated Microbiology System and 16S rRNA gene analysis to determine its taxonomy status. The ability of the strain to metabolize glycerol was investigated both genotypically and phenotypically using degenerate PCR and a glycerol minimal medium. Identification test results showed that strain JG3 belongs to genus Alcaligenes, with the closest relationship with A. faecalis and A. aquatilis (96% nucleotide similarity maximum). Degenerate PCR resulted in a 248-bp sequence showing 93% similarity with glpK of Candidatus Sodalis pierantonius SOPE, a key gene involved in glycerol metabolism. In vitro glycerol utilization test result showed that Alcaligenes sp. JG3 was able to grow on glycerol aerobically, but not anaerobically. It is concluded that Alcaligenes sp. JG3 possesses genes coding for glycerol metabolism and this trait is phenotypically expressed, thus making the strain potential to be used as an effective fat and oil biodegrader.

Microbial Enhanced Oil Recovery (MEOR) is a term which is attributed to the process of utilizing bacterial activity for increasing the recovery factor of oil reservoirs. This process relies on several mechanisms especially interfacial tension reduction and wettability alteration mechanisms. The main purpose of this work is to evaluate the impact of these mechanisms during MEOR process for microorganism isolated from formation water of one of the Iranian southwest carbonate oil reservoirs. The isolated microorganism was identified to be Alcaligenes faecalis. The optimum condition for growth of microorganism was found at 28 °C, pH = 7, carbon to nitrogen ratio of 30 and 3% salinity. Results show that the selected microorganism is able to reduce the interfacial tension between formation brine and crude oil from 28.1 mN/m to 8.4 mN/m and alter the wettability of reservoir rock from approximately 156° to 86° which represents a change from oil-wet condition toward intermediate-wet. Results show that the isolated microorganism is able to produce 8.2% and 5.2% additional oil recovery in respective shut in and quick flooding scenarios. This show that the isolated microorganism is efficient in production of additional oil as a part of tertiary oil recovery process. [ABSTRACT FROM AUTHOR]

Phytoextraction is a technique using a hyperaccumulator to remove heavy metals from soil. The efficiency of heavy metal uptake can be enhanced by the inoculation of endophytes. In this study, we isolated and identified 23 endophytes from Chromolaena odorata, a cadmium (Cd) hyperaccumulator that consisted of 19 bacteria, 2 actinomycetes and 2 fungi. All bacteria and fungi could produce at least 1 plant growth promoting factors. However, only 4 bacterial isolates; Paenibacillus sp. SB12, Bacillus sp. SB31, Bacillus sp. LB51, and Alcaligenes sp. RB54 showed the highest minimum inhibitory concentration (MIC) value (2.9 mM), followed by Exiguobacterium sp.RB51 (1.7 mM). Then, these 5 high-MIC bacteria and 1 low-MIC bacterium, Bacillus sp. LB15 were inoculated onto sunflower grown in soil supplemented with 250 mg/kg of Cd. After 60 days, all inoculated plants accumulated significantly higher Cd concentration than the non-inoculated counterparts, and those inoculated with strain LB51 showed the highest Cd accumulation and growth. Interestingly, strain LB15 with low MIC also enhanced Cd accumulation in plants. The results suggest that these bacteria, particularly strain LB51, could be applied to improve Cd accumulation in plants, and that bacteria with low MIC also have the potential to enhance the efficiency of phytoextraction. [ABSTRACT FROM AUTHOR]

The effects of Alcaligenes 637Ca, Agrobacterium A18, Staphylococcus MFDCa1, MFDCa2, Bacillus M3 and Pantoea FF1 were tested on peach cv. 'Elegant Lady' on GF677 and Nemaguard rootstocks. Average increases in citric, malic, oxalic, butyric and fumaric acid in the leaf were obtained from rhizobacterial root inoculations of 33.1, 17.5, 21.7, 26.5, and 44.7% in Elegant Lady/Nemaguard, respectively. FF1 showed the highest FC-R activity in the roots of Nemaguard (112.4 nmol FW gr−1 hr−2) and GF677 (162 nmol FW gr−1 hr−2). The highest FC-R activity in the leaf was with MFDCa2 in Elegant Lady/Nemaguard (57.1 nmol FW gr−1 hr−2) and 637Ca in Elegant Lady/GF677 (87.9 nmol FW gr−1 hr−2). PGPR strains used in this study expressed increased leaf organic acid content, FC-R activity in the roots and leaf, increased active Fe content in the leaf, and possessed a great potential for the improvement of iron availability to plants. [ABSTRACT FROM AUTHOR]

Alcaligenes hydrogenophilus was used to verify the role of the electron donor and acceptor in apparent CO 2 fixation of chemoautotrophic bacteria. The response mechanisms underlying the apparent CO 2 fixation characteristics with different concentrations of electron donor and acceptor were elucidated by analyzing the transcription characteristics of the cbbL gene, cytoskeleton synthesis efficiency and extracellular free organic carbon concentration. The results showed that the apparent CO 2 fixation efficiency of A. hydrogenophilus was significantly influenced by the electron donor (H 2 ), and the degree of electron donor oxidization was responsible for the variation in apparent CO 2 fixation efficiency. Furthermore, transcription efficiency of the cbbL gene at low electron donor concentration was lower than that at high electron donor concentration, but excessive electron donor concentrations did not further increase cbbL gene transcription efficiency significantly. High oxygen concentration was not advantageous to cbbL gene transcription efficiency in A. hydrogenophilus , but could improve cell growth rate (protein synthesis rate) and apparent CO 2 fixation efficiency, implying that cytoskeleton synthesis efficiency is another important factor determining apparent CO 2 fixation efficiency and its contribution maybe greater than that of cbbL transcription. The results also indicated that high apparent CO 2 fixation efficiency required the matching of electron donor and acceptor. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O) is a potent greenhouse gas and tends to accumulate as an intermediate in the process of bacteria denitrification. To achieve complete reduction of nitrogen oxide (NO x ) in bacteria denitrification, the structural gene nosZ encoding nitrous oxide reductase (N 2 OR) was cloned from Alcaligenes denitrificans strain TB (GenBank JQ044686 ). The recombinant plasmid containing the nos Z gene was built, and the expression of nos Z gene in Escherichia coli was determined. Results show that the nos Z gene consisting of 1917 nucleotides achieves heterologous expression successfully by codon optimization strategy under optimal conditions (pre-induction inoculum OD 600 of 0.67, final IPTG concentration of 0.5 mM, inducing time of 6 h, and inducing temperature of 28 °C). Determination result of gas chromatography confirms that N 2 O degradation efficiency of recombinant E. coli is strengthened by at least 1.92 times compared with that of original strain TB when treated with N 2 O as substrate. Moreover, N 2 OR activity in recombinant strain is 2.09 times higher than that in wild strain TB, which validates the aforementioned result and implies that the recombinant E. coli BL21 (DE3)-pET28b- nos Z is a potential candidate to control N 2 O accumulation and alleviate greenhouse effect. In addition, the N 2 OR structure and the possible N 2 O binding site in Alcaligenes sp. TB are predicted, which open an avenue for further research on the relationship between N 2 OR activity and its structure. [ABSTRACT FROM AUTHOR]

Bioflocculation producing bacteria isolated from soil and sediment in Da Lat City, Lam Dong province, Vietnam, were characterized. Four bacterial strains that had high flocculation activity were Flavobacterium granuli CL, Hydrogenophaga pseudoflava DA, Alcaligenes cupidus PT2, Bacillus mucilaginosus PT3, with the flocculation efficiency of 91.37%, 83.12%, 76.92%, and 75.81%, respectively at 22°C, pH 10, the initial algae concentration (optical density at 690 nm) of 1.25, and grown in media containing glucose as the carbon source. The bioflocculation efficiency was depended on the pH, carbon sources, the initial algae concentrations, bacteria strains, and the inital bioflocculant-producing bacteria concentrations. The temperature lightly affected the bioflocculation, no noticeable behavioral or activity changes were observed in mice that were orally administrated with four bacterial strains, and no treatment-related illness or death occurred after 72 hours. In general, the bioflocculation process is easy to operate, cost-effective, environment-friendly and therefore, it can be applied for industrial processing of microalgae. [ABSTRACT FROM AUTHOR]

In the current study, bacteria isolated from sea water samples of Murdeshwar, Karnataka, were screened for the production of alkaline protease by culturing them onto skim milk agar media. Of the isolated bacteria, Bacillus subtilis , Pseudomonas aeruginosa and Alcaligenes faecalis showed distinct zones of hydrolysis due to enzyme production. They were each inoculated into enzyme production media under submerged fermentation conditions at 37 °C for 48 h with a constant agitation of 120 rpm. Partial purification of alkaline protease was carried out by isoelectric precipitation. Enzyme activity was determined under varying conditions of pH, incubation temperature, different substrates, carbon and nitrogen sources and salt concentrations using sigma’s universal protease activity assay. Enzyme immobilization was carried out using 2% Sodium alginate and 0.1 M ice cold CaCl 2 and its activity under varying pH, temperature conditions and detergent compatibility was assayed. Efficacy of enzyme in stain removal was tested and haemolysis was observed within of 60 s which resulted in removal of the stain. Among the three organisms, enzyme from Bacillus subtilis showed highest activity in all cases indicating that it was the most ideal organism for enzyme production. [ABSTRACT FROM AUTHOR]