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In the current study, green synthesis of bimetallic Ag/Cu and Cu/Zn bimetallic nanoparticles were carried out using toddy and were characterized. The formed Ag/Cu bimetallic nanoparticles were brown in colour while the formed Cu/Zn nanoparticles were green. Simultaneous synthesis of bimetallic nanoparticles in a single pot was investigated using toddy and the formed nanoparticles were evaluated for their antitumor and antibacterial activities. The nanoparticles were investigated for their antibacterial activity against Alcaligenes faecalis, Staphylococcus aureus, Citrobacter freundii, Klebsiella pneumoniae and Clostridium perfringens while the antitumor activity was done against Nasopharyngeal cancer (KB) cells and Ehrlich ascites carcinoma (EAC) cell lines. This is the first report on the green synthesis of these bimetallic nanoparticles using Toddy palm. The significance of the results in the light of existing literature is discussed in the present study.

Some of the plant endophytes have ability to accumulate selenium from soil and provide it to the plant in turn benefiting plant's growth, such microbes are known as selenobacteria. Application of such endophytic selenobacteria may improve selenium biofortification in Glycine max crops under drought stress. Under present research we studied such phenomenon and claim the use of selenobacteria to have significant biotechnological application in agriculture. For this study, we isolated bacterial endophytes from the various tissues of Ricinus communis plant that was originally experimented for selenium enrichment. These isolates were assessed to reduce sodium selenite into elemental selenium and the efficient strains were tested on the growth of soybean plant grown under drought stress. Impact of selenobacteria on biofortification of selenium in plant tissues of Glycine max were assessed by HG-AAS. Moreover, selenobacteria also improved the growth of Glycine max plants was also observed under drought. Molecular identification using 16S rRNA gene sequence analysis suggested the potential strains MGT9, MGT16 and MGT18 to be Paraburkholderia megapolitana, Alcaligenes faecalis and Stenotrophomonas maltophilia respectively. From all the strains under study, Paraburkholderia megapolitana MGT9 was found to be most effective in improving the growth of Glycine max plant under drought along with showing exceptional selenium fortification that was 7.4 folds higher when compared to control. There was also an increase in the activity of plant stress markers, SOD, POD, CAT and GR in the fruit of Glycine max treated with MGT9 suggestive of better management of oxidative stress in plant induced by drought.

Quinolinic acid (QA) is an essential nitrogen-containing aromatic heterocyclic compounds in organisms and it also acts as an important intermediate in chemical industry, which has strong neurotoxicity and cytotoxicity. The wide range of sources and applications caused the release and accumulation of QA in the environment which might poses a hazard to ecosystems and human health. However, few research on the degradation of QA by microorganisms and toxicity of QA and its metabolites were reported. Alcaligenes faecalis JQ191 could degrade QA but the genetic foundation of QA degradation has not been studied. In this study, the gene cluster quiA1A2A3A4 was identified from A. faecalis JQ191, which was responsible for the initial catabolism step of QA. The quiA1A2A3A4 gene cluster encodes a novel cytoplasmic four-component hydroxylase QuiA. The

Lignocelluloses have been used as carbon sources for bioflocculant production. However, the low bioconversion efficiency of lignocellulose to bioflocculants is a major challenge. In this study, a lignocellulolytic strain of Alcaligenes faecalis-X3 was cultivated in ramie bio-degumming wastewater. Optimal production of ligninase, cellulase and bioflocculants (MBF-X3) was evaluated. The highest activity of MBF-X3 under the optimal conditions of pH 6.0 at 48 h of fermentation was 95.44%, with the maximum production of ligninase and cellulase (0.27 and 0.12 U/mL, respectively). The crude ligninase and cellulase had optimum activities at pH 5.0 and 40 °C and pH 6.0 and 50 °C, respectively. The cellulase activity was increased by Mn2+, Ca2+, Zn2+, and Mg2+ at 1 mM. The ligninase activity was significantly enhanced in the presence of Zn2+ at 10 mM. The flocculating activity of MBF-X3 was not changed by the addition of any metal cation. The results demonstrated that A. faecalis possesses an excellent enzyme system for the efficient bioconversion of lignocellulose into MBF-X3. Additionally, MBF-X3 has a high flocculating efficiency of Disperse Blue-2BLN (85.7%) at a dose of 1.0 g/L.

A green-house experiment was conducted to investigate the efficiency of three heavy metal-tolerant plant growth promoting bacterial strains (HMT-PGPB) (Alcaligenes faecalis MG257493.1, Bacillus cereus MG257494.1 and Alcaligenes faecalis MG966440.1 to alleviate the heavy metal’s toxic effects on sorghum plant (Sorghum bicolor, L.) in addition to their ability to enhance plant growth. The oxidative enzymes, photosynthetic pigments, growth characteristics, heavy metals uptake and heavy metals translocation factor (TF) were estimated in sorghum cultivated in soil contaminated with heavy metals under green-house conditions. Results showed that the application of these HTM-PGPB strains as biofertilizer of sorghum help plant to ignore the toxic effects of heavy metals and enhance growth characteristics.

Bacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16S rDNA sequencing. Process parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C, 150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR) in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found to be 81.5% and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can be described well by the pseudo-second order kinetics (R2 ≥ 0.978), indicating the major contribution of electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm suggested a maximum monolayer adsorption capacity of 4.69 mg g−1 at 40 °C which was very close to experimentally calculated value (4.97 mg g−1). Moreover, the Casuarina seed biochar was reusable 5 times.

A novel heterotrophic nitrifying bacterium with high salt and high ammonia nitrogen tolerance, Alcaligenes faecalis TF-1, was isolated from the leachate of a landfill. The verification of nitrogen removal efficiency of different nitrogen sources and PCR amplification electrophoresis results showed that the HN-AD pathway of the strain TF-1 was NH

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.

Various types of pigments are produced by different bacterial species and play multifunctional role including their role as a protective agent against environmental stresses. The present study deals with the isolation and characterization of melanin pigment from bacteria. Three isolates showed pigment production and identified as Klebsiella pneumoniae S-1, Alcaligenes faecalis PBI and Enterobacter sp. ABI on the basis of 16S rRNA gene sequencing. The maximum production of brown pigment (λmax 405 nm) was attained after 6 days of growth in liquid medium containing 3 g L−1 of l -tyrosine. Solubility test, FTIR and ESI-MS analysis suggested the nature of pigment as melanin. Identity of pigment type from all the three bacteria was made by HPLC analysis, results showed the presence of homogentisic acid (HGA), a precursor of pyomelanin. All the bacteria showed high activity of 4-hydroxyphenylpyruvate dioxygenase (HPPD) suggesting its role in HGA synthesis. PCR amplification of gene(s) also showed the presence of 4-hydroxyphenylpyruvate dioxygenase (hppD) gene coding for HPPD enzyme suggesting its role in pyomelanin synthesis. This study deals with only three bacterial isolates, isolation of such pigment from a large number of bacteria growing in harsh habitats may prove useful in finding novel type of melanin.

Rhizoremediation is a strategy where pollutant degrading bacteria are augmented through plant roots using plant-microbe interaction. Therefore, for effective rhizoremediation of pyrene contaminated soil, bacterial strains were experimented for amelioration of stress response in host plant along with biodegradation ability. A total of 28 bacteria, having ability to degrade polycyclic aromatic hydrocarbons were isolated from contaminated sites and checked for their plant growth promoting attributes, such as indole acetic acid (IAA) production, phosphate solubilization, atmospheric nitrogen fixation and siderophore release. Among these isolates, Klebsiella pneumoniae AWD5 was found to degrade 60% of pyrene. While other isolates, i.e. Alcaligenes faecalis BDB4, Pseudomonas fragi DBC, Pseudomonas aeruginosa PDB1, Acinetobactor sp. PDB4 degraded 48.5%, 50.29%, 31.3% and 36% of pyrene, respectively, after 6 days of incubation. K. pneumoniae AWD5 produced 94.2 μg/ml IAA and 3.1 mM/mg/h unit of ACC deaminase, which was best among eighteen indole acetic acid producers and five of the 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing isolates. P. aeruginosa PDB1 resulted in highest phosphate solubilization activity of 875.26 ng/ml of soluble phosphate among seven phosphate solubilizers. The isolates AWD5 and PDB1 both have shown a good amount of siderophore release (56.3% and 84.3% unit). There was 19.1% increase in shoot length of rice seedlings treated with PDB1 in presence of pyrene. Similarly, 26.5% increase in the root length of AWD5 treated rice was recorded in pyrene contaminated soil. Bacterial inoculation also induced and improved the stress response in host plant, in presence of pyrene, as suggested by the superoxide dismutase, glutathione and glutathione-S-transferase activities in rice.

The whole cell arylacetonitrilase of Alcaligenes faecalis MTCC 12629 was employed to develop a bioprocess for the synthesis of 4-hydroxyphenylacetic acid (4-HPAA) from 4-hydroxyphenylacetonitrile (4-HPAN). Isobutyronitrile emerged as the most appropriate inducer with a 1.2-fold enhanced nitrilase production in inducer feeding approach. A. faecalis MTCC 12629 nitrilase preferably hydrolyzed 4-HPAN, 4-aminoyphenylacetonitrile, mandelonitrile and phenylacetonitrile to their corresponding acids. Thermostability profile revealed the stability of nitrilase at 40, 45 and 50°C with the half-life of 45 h, 36 h and 13 h, respectively. Michaelis constant (Km) and reaction velocity (Vmax) of nitrilase were calculated as 20 mM and 2 U/mg dcw, respectively. This nitrilase exhibited complete conversion of 4-HPAN to 4-HPAA at 45°C in 50 mM K2HPO4/KH2PO4 buffer (pH 7.0) in 30 min. A fed batch process designed at 500 ml with five feedings of substrate resulted in 150 mM product formation using 18 U/ml whole cells nitrilase (16 mg/ml dcw) at 45°C. This is the first report on the production of 4-HPAA through nitrilase mediated pathway with the volumetric and catalytic productivity of 23 g/l and 4.13 g/g dcw/h, respectively.

A novel and ecofriendly procedure was developed for the synthesis of silver nanoparticles (FAgNPs) with the reduction of AgNO3. The flavonoids fractions (FF) of Psidium guajava leaves (PGL) were used as a green reducing and capping agent. Results showed that FF from PGL rapidly could synthesize into regular spheres and stable silver nanoparticles within 10 min. The average particle size of synthesized FAgNPs was 15–20 nm, with maximum absorbance wavelength at 420 nm. Moreover, FAgNPs exhibited a strong inhibition against the selected microorganisms, especially Alcaligenes faecalis, Escherichia coli and Aspergillus niger. Importantly, FAgNPs also possessed good catalytic degradation potency for organic dyes, namely, methyl orange and Coomassie brilliant blue G-250, under solar or UV irradiation. Overall, FAgNPs have good potential application prospects in the development of anti-bacterial materials and for the photocatalytic degradation of certain toxic dyes or chemicals, thereby paving the way for waste treatment and environmental bio-remediation.

The green synthesis of nanoparticles has become increasingly promising due to their potential applications in nanomedicine and materials science. In this study, silver nanoparticles (P-AgNPs) were synthesized from aqueous extracts of P. guajava L. leaf. The synthesized silver nanoparticles were confirmed by UV–vis spectrophotometry at 438 nm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zetasizer analyses showed that the average sizes of the P-AgNPs were 20–35 nm, 25 nm, and 25–35 nm, respectively. Element mapping analyses of the P-AgNPs were confirmed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) analyses. Moreover, FTIR spectra of the synthesized P-AgNPs showed the presence of phyto constituents as capping agents. Zeta potential measurements (−20.17 mV) showed that the synthesized P-AgNPs had reasonably good stability. The in vitro antioxidant properties of the P-AgNPs were evaluated using two different methods. A highly efficient radical scavenging activity of P-AgNPs possessing IC50 values of 52.53 ± 0.31 μg/mL (DPPH) and 55.10 ± 0.29 μg/mL (ABTS+) were confirmed. At a concentration of 100 μg/mL, antimicrobial activity assays of the P-AgNPs showed significant inhibition against selected bacteria, S. cerevisiae, A. niger and R. oryzae, especially against Alcaligenes faecalis and Escherichia coli. The present study revealed that the low-cost and environmentally friendly synthesis of P-AgNPs can be widely used in biomedicine, water treatment or purification, and nanobiotechnology.

Phenolics play a key role in communication between plants and microbes in the rhizosphere. In this study, shikimic, gallic, fumaric, ferulic, vanillic acid and quercetin in root exudates of Abelmoschus esculentus act as chemoattractants of endophytic Alcaligenes faecalis strains, BHU 12, BHU 16 and BHU M7. In vitro chemotaxis assay showed that BHU 12 expressed highest chemotactic movement (CFU ∼50×1012) towards A.esculentus root exudates followed by BHU 16 and BHU M7 (CFU∼ 9×1012), thereby confirming their ability to colonize the host rhizoplane region. However, BHU 16 expressed highest biofilm formation ability followed by BHU 12 and BHU M7. Assessment of chemotactic and biofilm formation potential towards individual phenolic acids revealed BHU 12 to be maximally attracted towards 1μM shikimic acid (2×1015) while BHU 16 towards 1mM vanillic acid (6.5×1012) and BHU M7 towards 1mM ferulic acid (3.5×1012), thereby confirming the phenolic acid components responsible for particularly attracting the endophytic isolates. Upon colonization, the endophytic isolates modified the phenolic profiles of root exudates in planta in a manner so as to plausibly attract more of the beneficial rhizospheric microbiota as well as self-fortification against pathogenic microbes. This hypothesis was verified by monitoring the changes in phenolic components of A. esculentus root exudate owing to S. rolfsii infection, a disastrous soil-borne pathogen. Thus, on the whole, the work provides intricate details of plant-endophyte interactions for biotic stress management through careful manipulation of root exudates, thereby aiding in sustainable agriculture.

The dynamics model of Alcaligenes faecalis NR was combined with the activated sludge model No. 1 to guide how to make the bioaugmentation of strain NR successful. Model studies show that conventional heterotrophic bacteria in activated sludge always outcompete strain NR. The competition between strain NR and Nitrosomonas, a typical ammonium-oxidizing bacterium (AOB), mainly depends on COD concentration and maximum growth rate of Nitrosomonas. 2000 mg/L of COD ensures that strain NR is always able to outcompete AOB. A biofilm reactor was developed to avoid a quick decrease in influent substrates. Approximately 94.2% of TN and 93.6% of COD were removed in the bioaugmented biofilm reactor, showing much better performance than an identical biofilm reactor without strain NR inoculation. A long-term experiment showed that strain NR successfully proliferated in the bioaugmented reactor. The abundance variation of strain NR mainly depended on influent COD concentrations, which was consistent with the model results.

Dipicolinic acid (DPA) is a widely distributed pyridine derivative containing two carboxylate groups. However, the catabolism of DPA mediated by microorganisms are rarely reported. Alcaligenes faecalis strain JQ135, previously isolated in our lab, was able to degrade various pyridine derivatives, including nicotinic acid (NA). In this study, it was found that strain JQ135 could utilize DPA as the sole carbon and nitrogen source for growth and degrade 1.8 mM (300 mg/L) DPA to a non-detectable level within 12 h. The catabolism of DPA by strain JQ135 extracted two intermediates, i.e., 3-hydroxy-2,6-dipicolinic acid and 4-imino-pent-2-enedioic acid. Moreover, deletion of the key genes essential for NA catabolism (such as moaCDEBmoeA and maiA) did not affect DPA catabolism, indicating that the maleamate pathway and molybdenum cofactor are not involved in the DPA catabolism by strain JQ135. This study will provide insights into the bacterial catabolism of DPA.

Given that (i) levulinic acid (LA) is one of the most significant platform chemicals derived from biomass and (ii) 4-hydroxyvaleric acid (4-HV) is a potential LA derivative, the aim of this study is to achieve chemoenzymatic valorization of LA, which was obtained from agricultural wastes, to 4-HV. The thermochemical process utilized agricultural wastes (i.e., rice straw and corncob) as feedstocks and successfully produced LA, ranging from 25.1 to 65.4 mM. Additionally, formate was co-produced and used as a hydrogen source for the enzymatic hydrogenation of LA. Finally, engineered 3-hydroxybutyrate dehydrogenase from Alcaligenes faecalis (eHBDH) was applicable for catalyzing the conversion of agricultural wastes-driven LA, resulting in a maximum concentration of 11.32 mM 4-HV with a conversion rate of 48.2%. To the best of our knowledge, this is the first report describing the production of 4-HV from actual biomass, and the results might provide insights into the valorization of agricultural wastes.

Silver nanoparticles have attracted much attention due to their potential applications in biomedical fields. In this study, silver nanoparticles (PAgNPs) were first synthesized using crude polysaccharides from Psidium guajava L. leaf (CP-PGL). The synthesized PAgNPs were characterized using several instrumental techniques and were regular spheres with an average size of 25–35 nm and a maximum absorbance at 435 nm. The results indicated that CP-PGL contains potential reducing agents for the rapid synthesis of benign and stable nanoparticles. Moreover, PAgNPs exhibited a high radical scavenging activity for DPPH and ABTS + as well as strong inhibition against five selected bacteria, especially Alcaligenes faecalis and Escherichia coli . The current study revealed that biosynthesis of PAgNPs with polysaccharides can be potentially applied to produce an antioxidant or antimicrobial agent for use in biomedical and cosmetic products.

The potential and mechanism of synthesized magnetic octahedral molecular sieve (Fe3O4@OMS-2) nanoparticles in enhancing the aerobic microbial ability of sequencing batch reactor (SBR) for treating dye wastewater have been revealed in this study. The addition of Fe3O4@OMS-2 of 0.25 g/L enhanced the decolorization of SBRs with an operation cycle of 24 h by more than 20%. The 16S rRNA gene high-throughput sequencing indicated Fe3O4@OMS-2 increased the microbial richness and diversity of SBRs, and more importantly, promoted the potential dye-degrading bacteria. After a series of enriching and screening, four bacterial strains with the considerable decolorizing ability were isolated from SBRs, designating Alcaligenes faecalis FP-G1, Bacillus aryabhattai FP-F1, Escherichia fergusonii FP-D1 and Rhodococcus ruber FP-E1, respectively. The growth and decolorization of these pure strains were promoted in the presence of Fe3O4@OMS-2, which agrees with the result of high-throughput sequencing. Monitoring dissolved Fe/Mn ions and investigating the change of oxidation states of Fe/Mn species discovered OMS-2 composition played the critical role in modulating the microbial community. The significant enhancement of Mn-oxidizing/-reducing bacteria suggested microbial Mn redox may be the key action mechanism of Fe3O4@OMS-2, which can provide numerous benefits for the microbial community and decolorization of SBRs.

Polycyclic aromatic hydrocarbons (PAHs) in soil retain for a quite long period due to their hydrophobicity and aggregation properties. Biofilm-forming marine bacterial consortium (named as NCPR), composed of Stenotrophomonas acidaminiphila NCW702, Alcaligenes faecalis NCW402, Pseudomonas mendocina NR802, Pseudomonas aeruginosa N6P6, and Pseudomonas pseudoalcaligenes NP103, was used for the bioremediation of PAHs in a soil microcosm. Phenanthrene and pyrene were used as reference PAHs. Parameters that can affect PAH degradation, such as chemotaxis, solubility of PAHs in extracellular polymeric substances (EPS), and catechol 2,3-dioxygenase (C23O) activity, were evaluated. P. aeruginosa N6P6 and P. pseudoalcaligenes NP103 showed chemotactic movement towards both the reference PAHs. The solubility of both the PAHs was increased with an increase in EPS concentration (extracted from all the 5 selected isolates). Significantly (P < 0.001) high phenanthrene (70.29%) and pyrene (55.54%) degradation was observed in the bioaugmented soil microcosm. The C23O enzyme activity was significantly (P < 0.05) higher in the bioaugmented soil microcosm with phenanthrene added at 173.26 ± 2.06 nmol min−1 mg−1 protein than with pyrene added at 61.80 ± 2.20 nmol min−1 mg−1 protein. The C23O activity and gas chromatography-mass spectrometer analyses indicated catechol pathway of phenanthrene metabolism. However, the metabolites obtained from the soil microcosm added with pyrene revealed both the catechol and phthalate pathways for pyrene degradation.

Contamination of the environment by heavy metals has been increasing in recent years due to industrial activities. Thus research involving microorganisms capable of surviving in multi-contaminated environments is extremely important. The objectives of the present study were to evaluate the removal of mercury alone and in the presence of cadmium, nickel and lead by four mercury-resistant microorganisms; estimate the removal of Cd, Ni and Pb; understand the mechanisms involved (reduction, siderophores, biofilms, biosorption and bioaccumulation) in the metal resistance of the isolate Pseudomonas sp. B50D; and determine the capacity of Pseudomonas sp. B50D in removing Hg, Cd, Ni and Pb from an industrial effluent. It was shown that the four isolates evaluated were capable of removing from 62% to 95% of mercury from a culture medium with no addition of other metals. The isolate Pseudomonas sp. B50D showed the best performance in the removal of mercury when evaluated concomitantly with other metals. This isolate was capable of removing 75% of Hg in the presence of Cd and 91% in the presence of Ni and Pb. With respect to the other metals it removed 60%, 15% and 85% of Cd, Ni and Pb, respectively. In tests with effluent, the isolate Pseudomonas sp. B50D removed 85% of Hg but did not remove the other metals. This isolate presented reduction, biosorption, biofilm production and siderophore production as its metal resistance mechanisms. Pseudomonas sp. B50D was thus a candidate with potential for application in the bioremediation of effluents with complex metal contaminations.

Cadmium-contaminated wastewater has attracted increasing concerns due to its non-biodegradable properties and high toxicity. To explore eco-friendly and economically feasible strategies, the screened Alcaligenes faecalis K2 were employed for the biomineralization and recovery of Cd2+ from wastewater while producing considerable secretory organo-biominerals (SOBs) as bioadsorbents. At 75 mg/L Cd2+ exposure, 85.5% of Cd2+ was removed by K2, 43.0% of which was fixed in the granular SOBs. SOBs were convenient for separating from the solution. The adsorption capacity of granular sorbent made from SOBs was verified to be greater than 77.1 mg/g. Practically, 89.5% of 75 mg/L of Cd2+ could be stably removed while ereK2 continuously generated SOBs in a moving-bed biofilm reactor (MBBR). To sum up, the production of bioadsorbents can be achieved by K2, while removing Cd with live microorganisms, which was conducive to making full use of materials and improving Cd removal efficiency.

Plant growth promoting rhizobacteria have the potential to mitigate abiotic stressors to improve plant productivity. The current study was conducted to isolate and characterize halo-tolerant PGPR strains from the native plants of Khewra salt mine in Pakistan. Two halo-tolerant bacterial strains (SBN01 and SBN02) were purified, examined in vitro for their plant growth-promoting traits, and inoculated on wheat plants to evaluate their beneficial effects. Both isolates were able to produce indole-acetic acid in tryptophan-supplemented media, both were N2 fixers and capable of solubilizing phosphate. These isolates also showed positive results for catalase, gelatinase, and ammonia, except for protease activity. Based on 16S rRNA gene sequence analysis, SBN01 and SBN02 isolates showed 100% homology with Alcaligenes faecalis. Inoculation studies on wheat plant showed that these isolates maintained ionic imbalance by regulating Na+ and K+ ions and significantly increased growth parameters and plant biomass by decreasing reactive oxygen species induced lipid peroxidation while increased accumulation of osmolyte, photosynthetic pigments and improved photosystem II efficiency as compared to uninoculated plants. These results showed that isolated halo-tolerant rhizobacterial strains could improve plant growth and enhance tolerance during a stressful environment. Thus, they can be used as potential cost-effective candidates for growing wheat in salt-affected areas.

The frequent use of antibiotics in artificial insemination promotes the development of antibiotic resistance. Therefore, alternatives must be considered. In this study, putative bioactive microalgae and hop extracts were examined to estimate their effect on quality and bacterial load of preserved porcine semen when used a low-temperature storage at 5 °C in Androstar® Premium (ASP) extender (Minitub). Firstly, five algae extracts (Neochloris oleoabundans (NEO), Pseudococcomyxa simplex (PSEY), Phormidium ambiquum (PHA), Schizochlamydella minutissima (SCH), Cyanidioschyzon merolae (CYA)) and one hop extract (Humulus lupulus (HOP)) in four concentrations (0.2, 2, 20 and 200 μg/mL) were tested on their sperm-compatibility at 17 °C. All extracts in the concentrations 0.2 and 2 μg/mL appeared to be sperm compatible. After 72 h of storage at 5 °C, variants showed an increase of total bacterial subcultures from 103 (ASP w/o supplements) to 113/136/135/136/126/118 (ASP w/NEO/PSEY/PHA/HOP/SCH/CYA). Even though bacterial growth was not inhibited in general, all extracts showed an antimicrobial effect on specific bacteria, including Gram-positive (Trueperella pyogenes, Streptococcus porcinus) and Gram-negative bacterial species (Alcaligenes faecalis, Pseudomonas aeruginosa, Ralstonia sp., Pasteurella sp., Proteus sp., Providencia stuartii, and Escherichia coli). While the proportion of these species was 10% in the control (ASP w/o supplements), their proportion in the supplemented variants ranged from 8% (NEO, HOP) to as low as 3% (PSEY). Although the tested extracts are not suitable to replace conventional antibiotics due to their lack of broad-spectrum antimicrobial activity, they nevertheless present promising opportunities for bacteria-specific, customizable usage in boar semen extenders combined with antibiotics or other antimicrobial agents.

Nitrogen and organic carbon are major pollutants in wastewater causing environmental problems. Alcaligenes faecalis strain NR, isolated from activated sludge, exhibited the ability to remove ammonium and organic carbon from wastewater simultaneously under sole aerobic conditions in batch culture. Changes in carbon type, C/N ratio, oxygen concentration and inorganic ions significantly affected the treatment efficiency. Furthermore, a continuous bioreactor, solely inoculated with A. faecalis strain NR, was conducted to assess its feasibility for simultaneous nitrogen and organic matter removal in a single aerated reactor. Approximately 66.7–78.3% of NH4+-N and 85.8–92.2% of TOC were removed by using synthetic wastewater with 150–200 mg/L of NH4+-N and 1350–2000 mg/L of TOC. This research would be valuable to develop an innovative treatment method for ammonium-rich wastewater under aerobic conditions.

Curdlan, a β-1,3-glucan isolated from Alcaligenes faecalis, is an agonist of dectin-1 in various immune cells, including dendritic cells (DCs). However, whether curdlan also activates DCs through other receptors remains unknown. In this study, we found that curdlan activates DCs through dectin-1 and toll-like receptor 4 (TLR4). Curdlan increased the expression levels of surface molecules (CD40, CD80, CD86, and MHC-I/II), the production of cytokines (IL-12, IL-1β, TNF-α, and IFN-β), migration toward MIP-3β, and allogeneic T cell stimulation activity of DCs. Curdlan increased the phosphorylation of Syk, Raf-1, Akt, MAPKs, IKK, and NF-κB p65 in DCs. However, curdlan only slightly activated DCs transfected with small interfering RNAs against dectin-1 or TLR4 and C3H/HeJ DCs, which have non-functional TLR4, in comparison with control DCs. Curdlan increased antitumor activity of DCs in a syngeneic tumor model. In summary, our data show that curdlan activates DCs through dectin-1 and TLR4 signaling and the combination of curdlan and DCs efficiently inhibit tumor growth in mice.

The feasibility of simultaneous biodegradation of phenol and ammonium in phenol-rich wastewater was evaluated in a reusable system, which contained macroporous adsorption resin and Alcaligenes faecalis strain WY-01. In the system, up to 6000mg/L phenol could be completely degraded by WY-01; meanwhile, 99.03±3.95% of ammonium was removed from the initial concentration of 384mg/L. This is the first study to show the capability of single strain in simultaneous removal of ammonium and phenol in wastewater containing such high concentrations of phenol. Moreover, the resin was regenerated during the biodegradation process without any additional manipulations, indicating the system was reusable. Furthermore, enzyme assay, gene expression patterns, HPLC-MS and gas chromatography analysis confirmed that phenol biodegradation accompanied with aerobic nitrifier denitrification process. Results imply that the reusable system provides a novel strategy for more efficient biodegradation of phenol and ammonium contained in some particular industrial wastewater.

Alcaligenes faecalis strain WT14 is heterotrophic nitrification and aerobic denitrification bacterium, newly isolated from a constructed wetland, and its feasibility in nitrogen removal was investigated. The result showed sodium citrate was more readily utilized by WT14 as a carbon source. The response surface methodology model revealed the highest total nitrogen removal by WT14 occurred at 20.3 °C, 113.5 r·min−1, C/N 10.8, and pH 8.4. Under adapted environmental conditions, up to 55.9 mg·L−1·h−1 of ammonium nitrogen (NH4+-N) was removed by WT14, and its NH4+-N tolerance ability reached 2000 mg·L−1. In addition to the reported high NH4+-resistance of Alcaligenes faecalis, WT14 multiplied fast and had strong nitrate or nitrite removal capacity when high strength nitrate or nitrite was provided as the single nitrogen source; which differed from other Alcaligenes faecalis species. These results show WT14 is a novel strain of Alcaligenes faecalis and its nitrogen removal pathway will be carried out in the further study.

The neonicotinoid insecticides, including thiamethoxam (THM) and imidacloprid (IMI), have become increasingly favored in the past decade due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD), the widespread disappearance of honey bees, which affects produce production on a global scale. The environmental persistence of neonicotinoids underscores the importance of developing a sustainable, ecologically-friendly remediation technique to remove residual insecticides from the environment. The present study characterizes the neonicotinoid bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. In Phase I, we evaluated the utilization of IMI or THM as the sole carbon or nitrogen source by P. fluorescens, P. putida, and P. aeruginosa. All three species were better able to utilize THM over IMI as their sole carbon or nitrogen source, and better growth was noted when THM was used as the sole nitrogen source compared to the sole carbon source. Thus, further studies proceeded with THM only. In Phase II, we assessed the kinetics of THM removal from aqueous media by the six species. Significant (pP. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over the 24-day study period, and for E. coli (60%) and S. lactis (12%) over the 14-day study period. The amount of time required to remove 50% of the THM in the media (T50) was: 12 days (d) (E. coli), 18 d (P. fluorescens), 19 d (P. putida), and 23 d (P. aeruginosa). Neither A. faecalis nor S. lactis achieved 50% removal during the study periods. The THM removal by all species followed a first-order kinetic reaction and half-lives were calculated accordingly. HPLC chromatograms of P. fluorescens, P. putida, and E. coli cultures revealed that as the area of the THM peak decreased over time, the area of an unidentified metabolite peak increased. In Phase II, we sought to characterize this metabolite and the overall metabolic efficiency of these three species. Maximal THM removal occurred at 30°C for all bacterial species assessed. Identification of the metabolite is currently underway, which will allow determination of whether the metabolite is less toxic than the parent compound, a prerequisite for this remediation technique to be viable. If the metabolite is found to be less hazardous than THM, further testing will follow to evaluate the use of this bioremediation technique in the field.

A electrochemical biosensor for As(III) determination has been developed by immobilization of the Alcaligenis faecalis bacteria on gold nanoparticle–modified screen–printed carbon electrode (AuNPs–SPCE). The detection of As(III) is due to the catalytic activity of arsenite oxidase enzyme which oxidizes As(III) to As(V) producing an analytical signal. To enhance the performance of the biosensor, was optimized the amount of bacteria, amount of glutaraldehyde and incubation time applied in the preparation of the electrode, in addition to the effect of pH and applied potential. The analytical application was carried out applying 300 mV (pH = 7) obtaining a LOD of 6.61 μmol L−1 (R = 0.9975) and 700 mV (pH = 12) obtaining a LOD of 1.84 μmol L−1 (R = 0.9983). AF/AuNPs–SPCE was applied to the determination of total arsenic in Loa river water samples after reduction, with satisfactory results.

A consortium of three heavy metals tolerant-plant growth promoting bacteria (HMT-PGPB) (Bacillus cereus MG257494.1, Alcaligenes faecalis MG966440.1 and Alcaligenes faecalis MG257493.1) was tested for its beneficial effects on microbial activities in sorghum’ rhizosphere (Sorghum vulgare L.). Moreover their ability to reduce heavy metals bioaccumulation in soil and plant during two successive experiments achieved in vitro and green-house. Firstly, the activities of HMT-PGPB consortium were estimated in vitro under mixture of four heavy metals (copper, cadmium, lead, zinc) at two concentrations (1000 and 1500 mgL−1), to confirm its heavy metal tolerance and plant growth promoting ability, then applied as a biofertilizer for sorghum cultivated in soil contaminated with heavy metals. In vitro results, no antagonism among the tested stains was observed and the HMT-PGPB consortium produced all estimated compounds. Greenhouse results proved that the inoculation of sorghum with HMT-PGPB consortium enhanced the microbial activities like increasing dehydrogenase activity (DHA), reduction of heavy metal bioaccumulation in roots and plants and regulate heavy metals bioaccumulation factor (BAF) in rhizosphere and plant. Moreover, the inoculation of sorghum with HMT-PGPB consortium increased the microbial activities and reduced the accumulation of heavy metals in soil, besides decrease BAF values in rhizosphere and plant. The importance of this study, is that enable us to cultivate the contaminated soils with heavy metals and not neglect large areas of such soils with reducing the environmental pollution, through the inoculation of plants by bacterial consortia, that can remove the polluting elements and at the same time stimulate plant growth.

High cost and low operational stability are the most important key challenges associated with the potential use of laccase for industrial applications. One possible solution to overcome these challenges is the immobilization of laccase. In this study, partially purified laccase from Alcaligenes faecalis XFI strain was immobilized onto chitosan beads (CB) and chitosan-clay composite beads (CCB) and employed for decolorization of three different synthetic dyes. The immobilization of laccase on CCB resulted in 88.4 % of immobilization yield and 151 U/g activity, which is higher than that of CB i.e. 83.6 % and 140 U/g respectively. This enhancement attributed to the synergetic effect of both clay and chitosan and their better biocompatibility with the laccase. The improved density (1.1002 g/mL), surface area (165.34 m2/g), pore volume (0.920 cm3/g), and pore size (33.12 nm) of the CCB evidenced the successful modification of chitosan matrix. The thermal stability, operational stability and reusability of the laccase immobilized on CCB was observed to be better than CB. The adsorption property of bentonite clay significantly enhanced the decolorization efficiency of laccase immobilized on CCB. The results indicate that laccase immobilized on CCB can be used for various industrial applications.

Endophytic microbes intricately modulate host defense pathways upon challenge with any form of environmental stress. In the current study, endophytic Alcaligenes faecalis treated okra plants were found to exhibit significant resistance to cell-lysis and disintegration upon infection with Sclerotium rolfsii. Apart from the morphological amendments, a systemic induction in phenolic content was observed in the endophyte treated hosts, such as that of gallic, cinnamic, synaptic, vanillic, ferulic, t-chlorogenic and gentisic acid as well as rutin, quercetin and kaempferol. Simultaneously, an upregulation of peroxidase (PO) and superoxide dismutase (SOD) was observed in the endophyte treated host leaf tissues along with significant lignification at the collar regions. Though similar number of isoforms of PO and SOD were observed in the endophyte treated plants and uninoculated control yet a higher intensity of the former suggests activation of defense pathways due to endophytic colonization. Thus this study may provide a thorough comprehension of the correlation among various defense pathways occurring simultaneously in planta upon endophyte treatment which particularly protect the host from S. rolfsii infection.

Colistin is a last resort drug used to treat infections caused by multidrug resistant Gram-negative bacteria that have developed resistance to carbapenem. The emergence and rapid dissemination of the nine plasmid-mediated mobile colistin resistance genes (mcr-1 to mcr-9) has led to fear of pan-drug resistant infections occurring worldwide. To date, there is only limited information on colistin resistance in African countries where the drug is widely used in agriculture. In this study from Nigeria, 583 non-duplicate bacterial strains were isolated from 1,119 samples collected from humans, camels, cattle, dogs, pigs and poultry by the use of colistin-supplemented MacConkey agar, and 17.0% of the isolates (99/583) were colistin resistant. PCRs (mcr-1 to mcr-9) and whole genome sequencing (WGS) identified mcr in 21.2% of the colistin-resistant isolates: mcr-1.1 (n=13), mcr-8.1 (n=5), both mcr-1.1 and mcr-8.1 (n=2), and mcr-1.1 and mcr-5 (n=1). Nine of the 21 mcr-positive strains were isolated from human samples, with eight being K. pneumoniae, and six of these human K. pneumoniae had a high colistin MIC of >64 µg/ml. In contrast, nine of the 12 mcr-positive animal isolates were E. coli of which only two had a colistin MIC of >64 µg/ml. Our study is the first to report mcr-1 in Alcaligenes faecalis, and emergence of mcr-5 and mcr-8 in Nigeria. WGS determined that mcr-1 was localized on IncX4 plasmid, and 95.2% of mcr-1 harboring isolates (20/21) transferred colistin resistance successfully in conjugation assay. Our findings highlight the global spread of colistin resistance, and emphasize the urgent need for coordinated global action to combat resistant bacteria.

Organic and nitrogen removals in two-stage membrane bioreactor (2-stage MBR) applied to the treatment of fresh, mixed, and partially stabilized leachate at different concentrations were investigated. A pilot-scale 2-stage MBR system was operated at a different hydraulic retention time of 2.5 and 1 days during which organic loading rates were varied between 1.5 and 20.2 kg BOD/m3 d. The effect of Alcaligenes faecalis no.4 bio-augmentation and its survival during the treatment was examined. High organic and nitrogen removals (>90%) was achieved when the system was applied to fresh and mixed leachate with BOD/COD of 0.5–0.76 but the removals of COD, TKN was reduced to 58–70% and A. faecalis no.4 population became extinct when partially stabilized leachate was pre-treated and reduced its BOD/COD to 0.11. This study demonstrates the applicability of 2-stage MBR to the treatment of leachate with varied characteristics provided that its treatment conditions were properly adjusted.

One of the major challenges for the coming years is to develop alternative forms of producing sustainable energy. Biodiesel has shown to be an option in substituting fossil fuels. It is produced by transesterification of a fat and a monoalcohol, thus releasing glycerol, which corresponds to 10% of the reaction volume. Large increments in biodiesel production will result in proportional volumes of crude glycerol. Studies have shown that strict anaerobic bacteria and fermentative bacteria are able to produce biohydrogen, a high-energy fuel, which does not generate gaseous pollutants during its combustion. Given the importance of increasing the added value of crude glycerol, the purpose of this study was to isolate and characterize bacteria found in reactors of wastewater and activated sludge treatment able to produce biohydrogen from glycerol. Fifteen bacterial species able to grow in medium with glycerol were identified by sequencing of the 16S rRNA gene, of which nine species were found to be able to produce biohydrogen: Enterobacter ludwigii , Shigella sonnei , Bacillus licheniformis , Bacillus amyloliquefaciens , Staphylococcus warneri , Alcaligenes faecalis , Bacillus subtilis , Bacillus atrophaeus , and Citrobacter freundii . The isolates of Bacillus amyloliquefaciens showed higher yield in biohydrogen production with values of 0.50 ± 0.20 mol H 2 /mol of glycerol. The results indicate that there is a great potential for selecting biohydrogen-producing bacteria in the wastewater evaluated.

A novel rapid method for bacterial differentiation is explored based on the specific adhesion pattern of bacterial strains to tunable polymer surfaces. Different types of counter ions were used to electrochemically fabricate dissimilar polypyrrole (PPy) films with diverse physicochemical properties such as hydrophobicity, thickness and roughness. These were then modulated into three different oxidation states in each case. The dissimilar sets of conducting polymers were exposed to five different bacterial strains, Deinococcus proteolyticus, Serratia marcescens, Pseudomonas fluorescens, Alcaligenes faecalis and Staphylococcus epidermidis. By analysis of the fluorescent microscope images, the number of bacterial cells adhered to each surface were evaluated. Generally, the number of cells of a particular bacterial strain that adhered varied when exposed to dissimilar polymer surfaces, due to the effects of the surface properties of the polymer on bacterial attachment. Similarly, the number of cells that adhered varied with different bacterial strains exposed to the same surface, reflecting the different surface properties of the bacteria. Principal component analysis showed that each strain of bacteria had its own specific adhesion pattern. Hence, they could be discriminated by this simple, label-free method based on tunable polymer arrays combined with pattern recognition. (C) 2015 Elsevier B.V. All rights reserved. Funding Agencies|Iranian Ministry of Science, Research and Technology; Linkoping University; Swedish Research Council [VR-2014-3079]

The purpose of this work was to evaluate chitosan edible films (CH) incorporated with maqui berry extracts (MB) for (i) the inhibition growth of some bacterial strains (ii) their total phenolic (TPC) and total flavonoid content and (iii) their antioxidant activity to define if the chitosan edible films incorporated with maqui berry extract (CH + MB) could be used as natural active films for food use. The antioxidant activity was determined with three different analytical assays: DPPH radical scavenging ability assay, Ferrous chelating capacity (FIC) and ferric reducing activity power (FRAP). The agar disc diffusion method was used to determine the antibacterial activity against Listeria innocua, Serratia marcescens, Aeromonas hydrophila, Achromobacter denitrificans, Alcaligenes faecalis, Pseudomonas fluorescens, Citrobacter freundii and Shewanella putrefaciens. CH + MB showed higher antioxidant activity, at all concentrations (0.5 and 1%) and with all methods assayed than CH. Furthermore, the antioxidant activity of CH + MB occurs in a concentration-dependent manner. Regarding the antimicrobial activity, CH + MB were effective against seven of the eight tested bacteria. This antibacterial activity takes place in a concentration-dependent manner. CH were not active, against six of the eight bacteria strain tested. CH + MB could improve the quality of foods due to delay the oxidation and the microbial growth.

The potential arsenite bioteansformation activity of arsenic was investigated by examining bacterial arsenic arsenite-oxidizing gene such as aoxS, aoxR, aoxA, aoxB, aoxC, and aoxD in high arsenic-contaminated drinking water produced from the surface water of floating houses. There is a biogeochemical cycle of activity involving arsenite oxidase aox system and the ars (arsenic resistance system) gene operon and aoxR leader gene activity in Alcaligenes faecalis SRR-11 and aoxS leader gene activity in Achromobacter xylosoxidans TSL-66. Batch experiments showed that SRR-11 and TSL-66 completely oxidized 1 mM of As (III) to As (V) within 35–40 h. The leaders of aoxS and aoxR are important for gene activity, and their effects in arsenic bioremediation and mobility in natural water has a significant ecological role because it allows arsenite oxidase in bacteria to control the biogeochemical cycle of arsenic-contaminated drinking water produced from surface water of floating houses.

The results on the effects of different anode potentials on current densities, coulombic efficiencies and microbial communities are contradictory and have not been studied with xylose, an important constituent of lignocellulosic materials. In this study, the effects of different anode potentials (+0.2, 0 and -0.2V vs. Ag/AgCl) on current generation, xylose degradation and microbial communities were examined with an exoelectrogenic enrichment culture originating from anaerobic sludge. Anode potential of +0.2V (vs. Ag/AgCl) resulted in the highest current density and coulombic efficiency of 1.5±0.2A/m2 and 62±11%, respectively, and there was no accumulation of soluble metabolites. With anode potentials of 0 and -0.2V the current densities remained low and acetate, butyrate and propionate were detected in the end of batch runs. Different anode potentials resulted in substantial differences in the anodic bacterial species. At more positive anode potentials, Ochrobactrum intermedium reported to be capable of direct electron transfer dominated. At more negative anode potentials, a known mediator-producer, Alcaligenes faecalis, and Desulfitobacterium hafnience, that has been reported to use mediated electron transfer, were detected. This study shows that the anode potential has a substantial effect on microbial communities and on xylose metabolism. acceptedVersion

Alcaligenes faecalis C16 was found to have the ability to heterotrophically nitrify and aerobically denitrify. In order to further understand its nitrogen removal ability and mechanism, the growth and ammonium removal response were investigated at different C/N ratios and ammonium concentrations in the medium with citrate and acetate as carbon source separately. Furthermore, experiments of nitrogen sources, production of nitrogen gas and enzyme assay were conducted. Results show that the bacterium converts NH4+-N and produces NH2OH during the growing phase and nitrite accumulation is its distinct metabolic feature. A. faecalis C16 is able to tolerate not only high ammonium concentration but also high C/N ratio, and the ammonium tolerance is associated with carbon source and C/N ratio. The nitrogen balance under different conditions shows that approximately 28%–45% of the initial ammonium is assimilated into the cells, 44%–60% is denitrified and several percent is converted to nitrification products. A. faecalis C16 cannot utilize hydroxylamine, nitrite or nitrate as the sole nitrogen source for growth. However, nitrate can be used when ammonium is simultaneously present in the medium. A possible pathway for nitrogen removal by C16 is suggested. The preliminary enzyme assay provides more evidence for this nitrogen removal pathway.

Semi-synthetic β-lactam antibiotics (SSBAs) are one of the most important antibiotic families in the world market. Their enzymatic synthesis can be catalyzed by penicillin G acylases (PGAs). In this study, to improve enzymatic synthesis of ampicillin, site-saturating mutagenesis was performed on three conserved amino acid residues: βF24, αR146, and αF147 of thermo-stable penicillin G acylase from Alcaligenes faecalis (Af PGA). Four mutants βF24G, βF24A, βF24S, and βF24P were recovered by screening the mutant bank. Kinetic analysis of them showed up to 800-fold increased kcat/Km value for activated acyl donor D-phenylglycine methyl ester (D-PGME). When βF24G was used for ampicillin synthesis under kinetic control at industrially relevant conditions, 95% of nucleophile 6-aminopenicillanic acid (6-APA) was converted to ampicillin in aqueous medium at room temperature while 12% process time is needed to reach maximum product accumulation at 25% enzyme concentration compared with the wild-type Af PGA. Consequently, process productivity of enzymatic synthesis of ampicillin catalyzed by Af PGA was improved by more than 130 times, which indicated an enzyme viable for efficient SSBAs synthesis.

This work aims to evaluate the biodegradation potential of petroleum by hydrocarbonoclastic bacteria isolated from Soummam wadi sediments. The chemical-biological properties of their biosurfactants products were also determined. Percentage of petroleum degraded by Rhodococcus ruber, Alcaligenes faecalis and Cellulosimicrobium sp. reached the maximum of 56.5 ± 1.2%, 52.7 ± 1.1% and 49.7 ± 1.2% respectively. Chemical profile study of the biosurfactants confirms their lipopeptide nature. The antifungal activity of these biosurfactants has given diameters of the zones of inhibition varying between 11.66 ± 0.57 mm and 18.33 ± 0.57 mm. The antioxidant activity showed a low activity for the antiradical power using the DPPH * and the molybdate test. The biosorption capacity of lead showed maximum biosorption of 74.91 ± 2.1 μg/g of Rhodococcus ruber biosurfactants. These bacterial isolates may find applications in bioremediation of petroleum spills. Thus their biosurfactants can furnish a choice to the current chemical compounds and they may find applications in biotechnologies.

Poly[(R)-lactate-co-(R)-3-hydroxybutyrate] [P(LA-co-3HB)] is a biobased polyester with semitransparent and flexible properties produced in engineered bacteria carrying an LA-polymerizing enzyme. In this study, we attempted to isolate the P(enriched LA-co-3HB)-degrading bacteria from soil samples in order to identify enzymes with the capacity to degrade this new type of polymer. Among approximately 500 samples, the Gram-negative bacterium C34, which exhibited potent P(enriched LA-co-3HB)-degrading activity, was isolated based on the decrease in the turbidity of culture medium supplemented with emulsified P(67 mol% LA-co-3HB). Based on its 16S rDNA sequence, this isolated bacterium was identified as a member of Variovorax sp.. Next, we attempted to isolate and purify the depolymerase that contributes to the polymer degradation from the culture supernatant of strain C34. The purified enzyme had a molecular mass of 42 kDa and exhibited degradation activity towards the P(67 mol% LA-co-3HB) as well as 3HB homopolymer [P(3HB)], but not LA homopolymers (PDLA and PLLA). On the other hand, a well-characterized depolymerase of P(3HB) derived from Alcaligenes faecalis T1 did not degrade P(67 mol% LA-co-3HB), PDLA or PLLA. This result suggests that the newly isolated depolymerase differs from the P(3HB) depolymerase from A. faecalis.

In the present investigation the production and characterization of a thermostable alpha-amylase enzyme from hot spring isolates Alcaligenes faecalis SSB17 has been studied. The individual and combined effect of temperature, pH and time has been investigated on the production of enzyme in four media (Luria Bertani, Nutrient Media, Semi-Synthetic Media l and Semi-Synthetic Media 2) using Box–Behnken design (BBD). Analysis of variance (ANOVA) shows high coefficient values of determination for each medium and satisfactory prediction second order regression models has been derived. Enzyme purification has been carried out by ammonium sulfate precipitation and size exclusion chromatography (SEC). Maximum purification has been obtained by SEC with 60 fold. SDS-PAGE of the purified enzyme has shown the presence of a single band associated with the amylase enzyme, having a molecular weight of 52 kDa

Alcaligenes faecalis strain No. 4 which is capable of heterogeneous nitrification and aerobic denitrification, was used to remove high-strength ammonium (approximately 1 g NH 4 + -N/l) from digested sludge, the product of an anaerobic digestion reactor, in which methane was produced from excess municipal sewage sludge. Repeated batch operations were conducted at 20°C and 30°C for 550 h, using a jar fermentor. The removal ratios of high-strength ammonium reached 90–100% within 24 h, and the average ammonium removal rate was 2.9 kg-N/m3/day, more than 200 times higher than that in conventional nitrification–denitrification processes. During these operations, the cell density was maintained at 108–109 cells of A. faecalis strain No. 4/ml. At 3% NaCl in the digested sludge, strain No. 4 exhibited an ammonium removal rate of 3 kg-N/m3/day.

An efficient biocatalytic process for the production of nicotinic acid (niacin) from 3-cyanopyridine was developed using cells of recombinant Escherichia coli JM109 harboring the nitrilase gene from Alcaligenes faecalis MTCC 126. The freely suspended cells of the biocatalyst were found to withstand higher concentrations of the substrate and the product without any signs of substrate inhibition. Immobilization of the cells further enhanced their substrate tolerance, stability and reusability in repetitive cycles of nicotinic acid production. Under optimized conditions (37 °C, 100 mM Tris buffer, pH 7.5) for the immobilized cells, the recombinant biocatalyst achieved a 100% conversion of 1 M 3-cyanopyridine to nicotinic acid within 5 h at a cell mass concentration (fresh weight) of 500 mg/mL. The high substrate/product tolerance and stability of the immobilized whole cell biocatalyst confers its potential industrial use.

Removal of chemical oxygen demand (COD) from wastewater has been of considerable interest for several decades, but detailed mechanisms are poorly known. Here we present an environmental friendly method for removing COD from coking wastewater by using chemically reduced nontronite (rNAu-2). Hydroxyl radicals (·OH) produced from oxidation of structural Fe(II) in rNAu-2 in phosphate buffer at pH 6.5, oxidized various compounds in wastewater and thus significantly decreased COD (from 199.10 ± 0.90 to 80.4 ± 1.97 mg/L) within 120 h. The amount of COD removal was positively correlated with the amount of ·OH production, with removal efficiency depending on pH and buffer type. Mass spectrometric analysis of dissolved organic matter (DOM) suggested an oxidative pathway for COD removal. Excitation-emission matrix (EEM) fluorescence spectroscopy showed that aromatic protein-like compounds accounted for a large fraction of DOM in initial wastewater, but after rNAu-2 treatment, their proportion decreased. A sequential treatment of wastewater by rNAu-2 and a common wastewater bacterium Alcaligenes faecalis demonstrated that different orders of chemical and biological treatments affected COD removal efficiency, likely because chemical and microbial treatments targeted different compounds in coking wastewater.

Sodium Diclofenac and Mefenamic Acid are Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) that contribute to aquatic environmental pollution. The present study illustrates the ability of a microbial consortium comprising of Alcaligenes faecalis, Staphylococcus aureus, Staphylococcus haemolyticus and Proteus mirabilis, to degrade the aforementioned drugs. Up to 89% of degradation of Sodium Diclofenac and 92% of degradation of Mefenamic Acid was observed within 120 h period at a concentration of 150 mg.L−1. The maximum specific growth rate (μmax) of the microorganisms was 0.096 mg.L−1 hr−1 and 0.0943 mg.L−1 hr−1 for Sodium Diclofenac and Mefenamic Acid respectively, while the maximum specific rate of biodegradation (Qmax) for Sodium Diclofenac was 0.89 mg.L−1 hr−1 and 0.95 mg.L−1 hr−1 for Mefenamic Acid. Residual metabolites predicted by spectroscopic analyses were Hydroxy-Sodium Diclofenac, Hydroxy-Mefenamic Acid, Carboxy-Mefenamic Acid and Acyl Glucuronide. The presence of the above metabolic products suggested that Mono-oxygenase and Glucuronidase enzyme activity catalysed the degradation reaction. The study highlights the potential of the microbial consortium in degrading two of the most environment sullying drugs and can possibly be used in the future.