Pseudomonas Monteilii Research Articles

Bioremediation of metal cyanide complexes from electroplating wastewater for long-term application using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2.

The purpose of this study was to investigate the optimum conditions, including aerobic and anoxic conditions, for operating a long-term bioreactor system to decrease the toxicity of industrial electroplating wastewater effluents containing metal cyanide using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2. The initial results revealed that bacteria performed better under aerobic conditions than under anoxic conditions. An aerobic bioreactor system was subsequently set up in a long-term study lasting 30days under optimum operating conditions. Both mixed-culture bacteria and indigenous bacteria promoted the high-efficiency treatment of cyanide and metals in the first 7days of the study. When the system had high removal rates, cyanide removal was greater than that of zinc, copper, nickel, and chromium (CN- > Zn > Cu > Ni > Cr), with removal efficiencies of 96.67%, 93.93%, 74.17%, 63.43%, and 44.65%, respectively, with residual concentrations of 0.15 ± 0.01, 0.24 ± 0.005, 0.03 ± 0.002, 18.41 ± 0.06 and 14.26 ± 0.15mg/L, respectively. The cell concentration in the bioreactor increased to approximately 107CFU/mL over 30days from initial cell concentrations of 6.15 × 105 CFU/mL and 1.05 × 103CFU/mL for the mixed culture and indigenous inoculation, respectively. These results implied that the bacteria were resistant to heavy metal toxicity. The addition of an appropriate carbon source with sufficient aeration to a bioreactor resulted in increased cyanide degradation.

Pseudomonas monteilii bacteremia and sepsis following insertable cardiac monitor implantation: a case report

BackgroundInsertable cardiac monitor implantation is a simple and safe procedure commonly performed in patients with embolic stroke with undetermined source. Routine periprocedural antibiotic use is not recommended, because infection rate is very low, although some local infection or gram-positive bacteremia have been reported. We report a case of Pseudomonas monteilii sepsis immediately after insertable cardiac monitor implantation.Case presentationA 55-year-old Korean male with embolic stroke of undetermined source presented with gram-negative sepsis immediately after implantable cardiac monitor implantation as a first reported complication after the procedure. Pseudomonas monteilii was identified in the blood culture, and no other infection source was seen. He was treated with intravenous antibiotics without removing the device.ConclusionsPrompt diagnosis and adequate management is required in such a patient with sepsis post-insertable cardiac monitor implantation procedure. It can be managed with adequate antibiotic treatment without device removal if there is no sign of inflammation at the insertion site. Further reports or studies should be investigated to reinforce this finding.Learning objectivesThe infection rate after insertable cardiac monitor insertion is extremely low; however, sepsis may occur without pocket infections. Physicians should be aware of signs of systemic infection, particularly when the procedure is performed outside the catheterization room. Sepsis after insertable cardiac monitor implantation can be managed with adequate antibiotic treatment without device removal if there is no sign of inflammation at the insertion site.

Genome characteristics of a MDR Pseudomonas monteilii carrying a novel VIM-type β-lactamase, blaVIM-84

ObjectivesThis study aimed to determine the genetic environment and characterize plasmid carrying a novel VIM-type β-lactamase (VIM-84) in a multidrug-resistant Pseudomonas monteilii isolate obtained from the human gut through whole-genome sequencing. MethodsDNA extraction of P. monteilii L2757hy was performed using the Genomic DNA Isolation Kit (QIAGEN, Hilden, Germany). Whole-genome sequencing was performed by Illumina NovaSeq 6000 and Oxford Nanopore platforms. The transferability of resistance genes was screened single clonal on MHA plates containing rifampicin and meropenem. Verification was performed using MALDI/TOF-MS and PCR with Pseudomonas aeruginosa PAO1Ri as the recipient strain. ResultsL2757hy was identified as P. monteilii through sequencing and ANI analysis. The genome was assigned as ST147 and comprised a 6,130,057 bp chromosome with a GC content of 61.8% and a 49,704 bp plasmid. Several resistance genes, including blaIMP-1, aac(6′)-IIa and tmexCD-toprJ, as well as virulence genes such as iroN, and wzaJ, were identified on the chromosome. A novel VIM-type blaVIM-84 was found on the plasmid, which was previously identified in Pseudomonas aeruginosa. Plasmid harboring blaVIM-84 was untypable, and it could be transferred to P. aeruginosa PAO1Ri and was associated with a class I integron with the genetic environment intI1-blaVIM-84-tniR-tniQ-tniB-tniA, likely derived from Tn402. ConclusionsOur study revealed that the novel blaVIM-84 gene was harbored by P. monteilii rather than P. aeruginosa. We suggested that P. monteilii may serve as a reservoir for resistance genes.

Rational design of short-chain dehydrogenase/reductase for enantio-complementary synthesis of chiral 1,2-diols by successive hydroxymethylation and reduction of aldehydes.

Enantiopure 1,2-diols are widely used in the production of pharmaceuticals, cosmetics, and functional materials as essential building blocks or bioactive compounds. Nevertheless, developing a mild, efficient and environmentally friendly biocatalytic route for manufacturing enantiopure 1,2-diols from simple substrate remains a challenge. Here, we designed and realized a step-wise biocatalytic cascade to access chiral 1,2-diols starting from aromatic aldehyde and formaldehyde enabled by a newly mined benzaldehyde lyase from Sphingobium sp. combined with a pair of tailored-made short-chain dehydrogenase/reductase from Pseudomonas monteilii (PmSDR-MuR and PmSDR-MuS) capable of producing (R)- and (S)-1-phenylethane-1,2-diol with 99% ee. The planned biocatalytic cascade could synthesize a series of enantiopure 1,2-diols with a broad scope (16 samples), excellent conversions (94%-99%), and outstanding enantioselectivity (up to 99% ee), making it an effective technique for producing chiral 1,2-diols in a more environmentally friendly and sustainable manner.

Immobilized consortium of heterotrophic nitrifying-aerobic denitrifying bacteria on various matrices for nitrogen removal from synthetic wastewater

Environmental contamination by nitrogen compounds such as ammonium and nitrate has increased extensively in the recent past, which necessitates the development of eco-friendly remediation technologies. In this study, three matrix types including pumice, aquarium ceramic filter, and calcium alginate beads were used to facilitate nitrogen removal with an immobilized heterotrophic nitrifying-aerobic denitrifying (HNAD) bacterial consortium. The HNAD bacterial consortium was made of Pseudomonas monteilii Nht, Pseudomonas mendocina AquaN, Rhodococcus erythropolis R1, and Acinetobacter calcoaceticus SCC2. The quality parameters for immobilization, such as the number of immobilized cells and their viability, were assessed. The highest number of bacterial cells (3.4 × 10 9) was immobilized on the aquarium ceramic filter, with 53% cell viability at 30°Ⅽ for two months. Pumice, aquarium ceramic filter, and calcium alginate achieved NH4+-N removal efficiencies of 85.3 ± 1.7%, 87.3 ± 2.2%, and 77.5 ± 3.99% within 24 h, respectively, and removed NO3−-N by 88.23 ± 0.36%, 93.95 ± 0.00%, and 71.29 ± 6.49% over 60 h. Additionally, immobilized cells on pumice and ceramic filter retained up to 84% of NH4+-N removal efficiency after 14 reuse cycles. These findings indicate that the immobilized HNAD bacterial consortium on the aquarium ceramic filter can be used as a suitable biofilter for treatment of high nitrogen wastewater.

Plant growth promoting activities of endophytic bacteria from Melia azedarach (Meliaceae) and their influence on plant growth under gnotobiotic conditions

Bacteria that live asymptomatically within plant tissues are known as endophytes. Because of the close relation with the plant host, they have been a matter of interest for application as plant growth promoters. Melia azedarach is a widely distributed medicinal tree with proven insecticidal, antimicrobial, and antiviral activity. The aim of this study was to isolate and characterize endophytic bacteria from M. azedarach and analyze their plant growth promoting activities for the potential application as biological products. Bacteria were isolated from roots and leaves of trees growing in two locations of Northeastern Argentina. The isolates were characterized by repetitive extragenic palindromic sequence PCR and 16S rDNA sequence analysis. The plant growth-promoting activities were assayed in vitro, improvement of plant growth of selected isolates was tested on M. azedarach plantlets, and the effect of selected ACC deaminase producing isolates was tested on tomato seedlings under salt-stress conditions. The highest endophytic bacterial abundance and diversity were obtained from the roots. All isolates had at least one of the assayed plant growth-promoting activities and 80 % of them had antagonistic activity. The most efficient bacteria were Pseudomonas monteilii, Pseudomonas farsensis, Burkholderia sp. and Cupriavidus sp. for phosphate solubilization (2064 μg P ml−1), IAA production (94.7 μg ml−1), siderophore production index (5.5) and ACC deaminase activity (1294 nmol α-ketobutyrate mg−1 h−1). M. azedarach inoculation assays revealed the bacterial growth promotion potential, with Pseudomonas monteilii, Pseudomonas farsensis and Cupriavidus sp. standing out for their effect on leaf area, leaf dry weight, specific leaf area, and total Chl, Mg and N content, with increases of up to 149 %, 58 %, 65 %, 178 %, 76 % and 97.7 %, respectively, compared to NI plants. Efficient ACC deaminase-producing isolates increased stress tolerance of tomato plants under saline condition. Overall, these findings indicate the potential of the endophytic isolates as biostimulant and biocontrol agents.

Mechanisms and Applications of Pseudomonas monteilii SX001: A Promising Agent for Improving Cucumber Tolerance to Salt Stress

To investigate the effects of Pseudomonas monteilii SX001 on various parameters of cucumber plants under salt stress, the salt-sensitive cucumber variety “Jinyou No. 4” was used as the test material, and coconut bran was used to simulate salt stress by applying NaCl solution. The results indicated that salt stress significantly reduced the morphological structure, relative growth rate, root morphology, and photosynthetic parameters of the cucumber plants. Leaf starch, soluble sugar, and sucrose contents significantly increased, whereas their levels in roots decreased. Cell membrane damage leads to the accumulation of reactive oxygen species and malondialdehyde, with notable increases in the activities of major antioxidant enzymes such as SOD, CAT, and POD. Nitrogen metabolism was disrupted, as evidenced by a significant decrease in nitrate nitrogen content and an increase in ammonium nitrogen content, as well as a significant reduction in the activity of NR enzymes involved in nitrogen metabolism. The enzyme activity in the cucumber rhizosphere soil decreased. However, Pseudomonas monteilii SX001 significantly enhanced the growth of cucumber seedlings under salt stress, improved photosynthetic efficiency, and facilitated sugar transformation and transport via glucose metabolism. Additionally, Pseudomonas monteilii SX001 reduced the reactive oxygen content and increased antioxidant enzyme activity. It also increased the activity of substrate enzymes and decreased the diversity of rhizosphere soil microorganisms but also increased the abundance of Asticcacaulis, Acinetobacter, Brevundimonas, Pseudomonas, and Enterobacter. These findings demonstrate that Pseudomonas monteilii SX001 is a promising bioinoculant for alleviating salt stress in cucumber production and improving soil health.

Comparative evaluation of biodegradation of chlorpyrifos by various bacterial strains: Kinetics and pathway elucidation

The present study focused on the isolation and identification of CP and TCP bacteria degrading bacteria from the rhizospheric zone of aromatic grasses i.e. palmarosa (Cymbopogon martinii (Roxb. Wats), lemongrass (Cymbopogon flexuosus) and vetiver (Chrysopogon zizaniodes (L.) Nash.). So that these isolates alone or in combination with the vegetation of aromatic grasses will be used to clean up CP-contaminated soils. The study also explored enzymatic activities, CO2 release, dechlorination potential, and degradation pathways of bacterial strains. A total of 53 CP-tolerant bacteria were isolated on their physical characteristics and their ability to degrade CP. The ten highly CP-tolerant isolates were Pseudomonas aeruginosa Pa608, three strains of Pseudomonas hibiscicola R4–721 from different rhizosphere, Enterococcus lectis PP2a, Pseudomonas monteilii NBFPALD_RAS131, Enterobacter cloacae L3, Stenotrophomonas maltophilia PEG-390, Escherichia coli ABRL132, and Escherichia coli O104:H4 strain FWSEC0009. The CO2 emission and phosphatase activities of the isolates varied from 3.1 to 8.6 μmol mL−1 and 12.3 to 31 μmol PNP h−1, respectively in the CP medium. The degradation kinetics of CP by these isolates followed a one-phase decay model with a dissipation rate ranging from 0.048 to 0.41 d−1 and a half-life of 1.7–14.3 days. The growth data fitted in the SGompertz equation showed a growth rate (K) of 0.21 ± 0.28 to 0.91 ± 0.33 d−1. The P. monteilii strain had a faster growth rate while E. coli ABRL132 had slower growth among the isolates. The rate of TCP accumulation calculated by the SGompertz equation was 0.21 ± 0.02 to 1.18 ± 0.19 d−1. The Pseudomonas monteilii showed a lower accumulation rate of TCP. Among these, four highly effective isolates were Pseudomonas aeruginosa Pa608, Pseudomonas monteilii NBFPALD_RAS131, Stenotrophomonas maltophilia PEG-390, and Pseudomonas hibiscicola R4–721. Illustrations of the degradation pathways indicated that the difference in metabolic pathways of each isolate was associated with their growth rate, phosphatase, dehydrogenase, oxidase, and dechlorination activities.

Transmission patterns of multiple strains producing New Delhi metallo-β-lactamase variants among animals and the environment in live poultry markets

The widespread transmission of blaNDM among livestock and the live poultry industry attracts considerable public attention. However, studies have not yet addressed its impact on public health in live poultry markets (LPMs). Herein, we investigated the prevalence and genomic epidemiology of blaNDM-positive bacteria in various niches, and explored the transmission patterns of blaNDM within LPMs. Samples were collected between 2019 and 2022 from two LPMs in China. blaNDM was most prevalent in wastewater (35/66, 53.03%). All vegetable samples were negative for blaNDM. blaNDM was mainly distributed among Escherichia coli (266/336, 79.17%), Klebsiella pneumoniae (62/336, 18.45%), and Acinetobacter baumannii (3/336, 0.89%). Some novel hosts, including Pseudomonas monteilii and Pseudomonas otitis, were also identified. Diverse variants blaNDM-1, blaNDM-5, blaNDM-9, blaNDM-13, and blaNDM-27 were identified. The blaNDM-positive E. coli ST2659 was dominant. blaNDM was found to coexist with mcr-1 (4/51, 7.84%). Horizontal gene transfer plays a vital role in blaNDM transmission within the LPMs. Some blaNDM-harboring clones transfer among animals and the environment through the food chain and close contact. More efforts are needed to curb the transmission trend of blaNDM among humans, animals, and the environment within LPMs.

Bio-sorption capacity of cadmium and zinc by Pseudomonas monteilii with heavy-metal resistance isolated from the compost of pig manure

The tolerance of Pseudomonas monteilii X1, isolated from pig manure compost, to Cd and Zn, as well as its capacity for biosorption, were investigated. The minimum inhibitory concentrations (MIC) of Cd and Zn for the strain were 550 mg/L and 800 mg/L, respectively. Untargeted metabolomics analysis revealed that organic acids and derivatives, lipids and lipid-like molecules, and organic heterocyclic compounds were the main metabolites. The glyoxylate and dicarboxylate metabolism pathway were significantly enriched under Cd2+ stress. The isothermal adsorption and adsorption kinetics experiments determined that the strain had adsorption capacities of 9.96 mg/g for Cd2+ and 23.4 mg/g for Zn2+. Active groups, such as hydroxyl, carboxyl, and amino groups on the cell surface, were found to participate in metal adsorption. The strain was able to convert Zn2+ into Zn3(PO4)2·4H2O crystal. Overall, this study suggested that Pseudomonas monteilii has potential as a remediation material for heavy metals.

Evaluating Pseudomonas monteilii JK-1 as an in-feed probiotic: Enhancing growth, immune-antioxidant, disease resistance and modulating gut microflora composition in grass carp (Ctenopharyngodon idella)

Host-derived probiotics are microorganisms sourced from the host's gut environment, aimed at enhancing growth and overall health. Given the increasing stringency in the regulation of antibiotics within animal production, the adoption of in-feed probiotics has emerged as a compelling antibiotic alternative in aquaculture. Here, we investigate the impact of Pseudomonas monteilii JK-1 on the growth performance and disease resistance of grass carp (Ctenopharyngodon idella). The results indicate that P. monteilii JK-1 leads to a significant increase in weight gain (WG), specific growth rate (SGR), and survival rate, along with a substantial reduction in pathogen load (Aeromonas) (P < 0.05). Furthermore, we observed a noteworthy improvement in the expression of key immune-related genes, including interleukin 1β (IL-1β), interleukin 10 (IL10), tumor necrosis factor alpha (TNF-α), and transforming growth factor beta (TGF-β) in both the head kidney and gut (P < 0.05). This effect extends to the augmentation of the activities of crucial antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in both liver and gut tissues (P < 0.05). Notably, P. monteilii JK-1 exerts a positive influence on the complexity of the gut microbiome ecological network. In this context, Cetobacterium emerges as a keystone microbiota responsible for maintaining interspecies interactions and enhancing gut network stability. Moreover, our study establishes a positive connection between Cetobacterium and growth performance and between Akkemansia and immune response, respectively. In addition, the result of partial least squares path model (PLS-PM) showed that P. monteilii JK-1 does not directly enhance growth performance and pathogen resistance but does so by regulating keystone taxa and promoting gut network stability. Collectively, this study offers a nuanced comprehension of how probiotics enhance growth and boost disease resistance, focusing on the gut microbial ecological network. These findings showed that P. monteilii JK-1 has potential application as a probiotic in grass carp, which may provide a new strategy of preventing and controlling bacterial diseases in this species.

Isolation, Characterization, and Investigation on Potential Multi-trait Plant Growth Promoting Rhizobacteria from Wild Banana (Musa itinerans) Rhizospheric Soil

The undertaken study was conducted to isolate and characterize the plant growth promoting rhizobacteria from the rhizospheric soil of Musa itinerans collected from Zaphumi village, Nagaland, Northeast India. The purified bacterial isolates were screened for plant growth-promoting traits namely phosphate solubilization, IAA production, siderophore production, and ammonia production. Out of the 25 isolates, the three best isolates with maximum growth promoting traits were selected and considered for further study for heavy metal and salinity tolerance. All three isolates were able to produce siderophore, whereas, only isolate EZ30 was able to produce IAA. Phosphate solubilization ability was the highest in EZ27 (272.89±2.46), followed by EZ30 (109.70±5.47) and EZ11(89.12±1.87). The isolates also exhibited variable levels of cadmium (30- 280µg/ml) and salinity resistance (2-14%). Based on 16S-rRNA gene sequence analysis, these bacterial isolates were identified as Kosakonia arachidis, Pseudomonas putida and Pseudomonas monteilii. The highest salinity tolerance was shown by P. putida (14%), whereas K. arachidis (4%) and P. monteilii (4%) exhibited similar level of tolerance. The cadmium tolerance was the highest for P. monteilii (280 µg/ml), followed by K. arachidis (80 µg/ml) and P. putida (30 µg/ml). Inoculation of Cicer arietinum L. with these three isolates significantly enhanced the growth parameter such as shoot and root length (p≤ 0.05), root and shoot fresh weight and dry weight (p≤ 0.05), except for EZ27 and EZ11 where there was no significant difference in shoot dry weight (p≥ 0.05). Overall, the three selected PGPR strains showed potential biofertilizer traits (phosphate solubilizing, IAA producing, siderophore production, salinity, and cadmium tolerant) to be used in the agricultural fields promoting sustainable practices.

The pygidial gland secretion of Laemostenus punctatus (Coleoptera, Carabidae): a source of natural agents with antimicrobial, anti-adhesive, and anti-invasive activities

In the present study, we investigated in vitro the antimicrobial activity of the pygidial gland secretion of the guanophilic ground beetle Laemostenus (Pristonychus) punctatus (Dejean, 1828) and some of its chemicals against resistant and non-resistant bacteria and Candida species, the synergistic and additive potential of combinations of selected chemicals and antimicrobial drugs against resistant bacterial and fungal strains, anti-adhesive and anti-invasive potential of the secretion and formic acid alone and in selected combinations with antimicrobial drugs against methicillin-resistant Staphylococcus aureus (MRSA) toward spontaneously immortalized human keratinocyte cell line (HaCaT cells). In addition, we examined the antiproliferative activity of the secretion and formic acid in vitro. The tested secretion and the standards of formic and oleic acids possessed a significant level of antimicrobial potential against all tested strains (P &amp;lt; 0.05). The isolate from guano Pseudomonas monteilii showed the highest resistance to the secretion and formic acid, while MRSA achieved a significantly high level of susceptibility to all agents tested, particularly to the combinations of formic acid and antibiotics, but at the same time showed a certain level of resistance to the antibiotics tested individually. Candida albicans and C. tropicalis were found to be the most sensitive fungal strains to the secretion. Formic acid (MIC 0.0005 mg/mL) and gentamicin (MIC 0.0010 mg/mL) in the mixture achieved synergistic antibacterial activity against MRSA (FICI = 0.5, P &amp;lt; 0.05). The combination of formic acid, gentamicin and ampicillin accomplished an additive effect against this resistant bacterial strain (FICI = 1.5, P &amp;lt; 0.05). The secretion achieved a better inhibitory effect on the adhesion ability of MRSA toward HaCaT cells compared to formic acid alone, while formic acid showed better results regarding the invasion (P &amp;lt; 0.001). The combinations of gentamicin and ampicillin, as well as of formic acid and gentamicin and ampicillin achieved similar anti-adhesive and anti-invasive effects, with a slight advantage of formic acid and antibiotics in combination (P &amp;lt; 0.001). The secretion and formic acid were found to be non-toxic to HaCaT cells in vitro (IC50 ≥ 401 μg/mL).

Multidisciplinary evaluation of plant growth promoting rhizobacteria on soil microbiome and strawberry quality

The natural soil environment is considered one of the most diverse habitats containing numerous bacteria, fungi, and larger organisms such as nematodes, insects, or rodents. Rhizosphere bacteria play vital roles in plant nutrition and the growth promotion of their host plant. The aim of this study was to evaluate the effects of three plant growth-promoting rhizobacteria (PGPR), Bacillus subtilis, Bacillus amyloliquefaciens, and Pseudomonas monteilii for their potential role as a biofertilizer. The effect of the PGPR was examined at a commercial strawberry farm in Dayton, Oregon. The PGPR were applied to the soil of the strawberry (Fragaria × ananassa cultivar Hood) plants in two different concentrations of PGPR, T1 (0.24% PGPR) and T2 (0.48% PGPR), and C (no PGPR). A total of 450 samples from August 2020 to May 2021 were collected, and microbiome sequencing based on the V4 region of the 16S rRNA gene was conducted. The strawberry quality was measured by sensory evaluation, total acidity (TA), total soluble solids (TSS), color (lightness and chroma), and volatile compounds. Application of the PGPR significantly increased the populations of Bacillus and Pseudomonas and promoted the growth of nitrogen-fixing bacteria. The TSS and color evaluation showed that the PGPR presumptively behaved as a ripening enhancer. The PGPR contributed to the production of fruit-related volatile compounds, while the sensory evaluation did not show significant differences among the three groups. The major finding of this study suggests that the consortium of the three PGPR have a potential role as a biofertilizer by supporting the growth of other microorganisms (nitrogen-fixing bacteria) as part of a synergetic effect and strawberry quality such as sweetness and volatile compounds.

Isolation of indole biodegrading bacterial species from petroleum contaminated site of northeast India: Growth kinetics and crude oil biodegradation assessment

Petroleum industrial activities such as crude oil spillage, sludge generation, and effluent wastewater adversely affects the surrounding ecosystem. Several biological processes have been developed so far to remediate the petroleum contaminants. This article is focused on the remediation of petroleum waste using novel bacterial isolates from petroleum-contaminated sites. The indole biodegradation was studied in bioreactor wherein 84.86 % COD removal was observed using consortium of Alcaligenes faecalis RB-10, Pseudomonas guariconensis RB-12 and Pseudomonas monteilii RB-29. The residual analysis of biodegraded samples were performed using various analytical techniques. The maximum specific growth rate (μmax) and half-saturation rate constant (ks) were evaluated individually for Alcaligenes faecalis RB-10, Pseudomonas guariconensis RB-12 and Pseudomonas monteilii RB-29 species using Monod model. The crude oil degrading potential of isolated bacterial consortium was also investigated.

Synergism Between Multi-Pseudomonas and Cutinase for Biodegradation of Crude Oil-Based Derivatives.

Polyethylene terephthalate (PET) as one of the main crude oil-based derivatives, produces a significant amount of waste that is difficult to degrade. Currently, microbial degradation of PET is an eco-friendly, efficient, and economical method. This study was conducted to propose a novel screening strategy for PET-degrading bacteria, and evaluate their degradation efficiency of PET. Two strains, Pseudomonas nitroreducens S8 and Pseudomonas monteilii S17, were isolated and could utilize PET as a carbon source by co-culture. The combined use of both bacteria gave a synergistic effect on the disruption of the PET surface through colonization behavior, which could enhance the subsequent degradation of PET. Its time of reaching a peak value of PET degradation rate (94.5% at 6 d) was 2days earlier than these of single bacteria. A similar synergistic effect was also observed in the metabolization of PET monomers, and the metabolic rate was expressed as 82.4% of bis (2-hydroxyethyl) terephthalate (BHET), 64.0% of mono (2-hydroxyethyl) terephthalate (MHET), and 20.0% of terephthalic acid (TPA), respectively. This study is novel in showing the degradation of PET waste by combinations of bacterial pretreatment and enzymatic treatment, which can be a promising method.

Decolourization and Detoxification of Azo Dye, Malachite Green by Pseudomonas monteilii Strain RZT1, a Bacterium Isolated from Textile Wastewater

Discharge of textile industrial effluent without proper treatment has become a severe hazard for the animal health and environment worldwide. Therefore, this study was designed to isolate azo dye-degrading bacteria from textile wastewater and evaluate their ability to biodegrade reactive dyes into non-toxic products. The potent bacterial strain which was isolated from textile wastewater was identified as Pseudomonas monteilii strain RZT1 on the basis of 16S rDNA sequence. The isolated bacterial strain exhibited good decolorization ability with yeast extract supplementation as cosubstrate in static conditions for Malachite Green dye. The optimal condition for the decolorization of Malachite Green dye by P. monteilii strain RZT1 were at pH 7.0 and 28°C. Decolorization rates of Malachite Green dye by P. monteilii strain RZT1 were varied with initial dye concentration as follow: 84.8%, 75.4%, 63.4% and 45.5% decolorization for 100ppm, 200ppm, 300ppm and 400ppm initial dye concentration respectively. We investigated the effects of dyes used in the textile industry on the seed germination of Five crops - Rice (Oryza sativa), Wheat (Triticum aestivum L.), Khesari (Lathyrus sativus), Mustard (Brassica nigra) and Bitter Melon (Momordica charantia). It was found that textile dye Malachite Green had negative effect on seed germination and seedling growth in test cultures. The harmful effects of dye on seed germination and early seedling growth parameters were augmented with increase of dye concentration. Interestingly, treatment of the Malachite Green dye with isolated bacteria reduced the adverse effects of that dye on seed germination and seedling growth. Thus, it indicated the potentiality of P. monteilii strain RZT1 for bioremediation of textile effluents into a non-toxic form for plants.

Deracemisation of racemic 2-substituted indolines by monoamine oxidase from Pseudomonas monteilii ZMU-T01

Monoamine oxidase strain (MAO-5) from Pseudomonas monteilii ZMU-T01 mediated oxidative resolution of racemic 2-substituted indolines has been successfully described. A series of highly enantioselective 2-substituted indoline derivatives were obtained in up to 50 % conversion and >99 % ee.

Optimization and identification of siderophores produced by Pseudomonas monteilii strain MN759447 and its antagonism toward fungi associated with mortality in Dalbergia sissoo plantation forests.

Siderophore-positive bacteria present in the rhizosphere and in bulk soil assist plants by either inhibiting phytopathogen proliferation or increasing plant growth. The bacterial diversity of the Shisham forest ecosystem in the Tarai region of the Western Himalayas was studied and used for siderophore production, taking into account the large-scale dieback and wilt-induced mortality in Dalbergia sissoo (common name: shisham) plantation forests and the importance of soil microbes in tree health. In addition, Pseudomonas, Burkholderia, and Streptomyces were prominent siderophore-positive bacteria in Shisham forests. Pseudomonas species are known for their remarkable siderophore-producing ability. Bacterial siderophores inhibit pathogen growth by rapidly lowering the number of ferric ions in the rhizosphere. The Pseudomonas monteilii strain MN759447 was isolated from a D. sissoo plantation forest at the Agroforestry Research Centre, Pantnagar, Uttarakhand (28°58'N 79°25'E/28.97°N 79.41°E). It produces a significant number of siderophore units (80.36% in total). A two-stage optimization of growth factors was attempted in the strain MN759447 for better siderophore recovery. In the first-stage single-factor experiment, among the five variables studied, only pH, NH4NO3 concentration, and Fe concentration affected siderophore synthesis. In the second stage, an optimization of pH, NH4NO3 concentration, and Fe concentration for improved growth and enhanced siderophore production was carried out using a Box-Behnken design with response surface methodology. By using LC-MS, two derivatives of pseudomonine, salicylic acid, and kynurenic acid were detected as siderophores in the purified XAD-2 methanol extract of the P. monteilii strain MN759447. In addition to siderophore production, the P. monteilii strain MN759447 also exhibited a broad range of antagonistic activity against Aspergillus calidoustus (65%), Fusarium oxysporum (41.66%), Talaromyces pinophilus (65%), and Talaromyces verruculosus (65.1%) that are linked to sissoo mortality. To our knowledge, this is the first report on siderophore-producing bacteria isolated, identified, and characterized from the D. sissoo Roxb. forest habitat. This strain can also be developed as a commercial product.

Understanding the mechanism of action of stress-acclimatized rhizospheric microbiome towards salinity stress mitigation in Vigna radiata: A focus on the emission of volatiles

Microbiome-based rhizospheric engineering has emerged as a promising approach towards attaining agricultural sustainability. While the top-down approach of acclimatizing the rhizospheric microbiome to stressors is relatively easy to perform, the mechanisms involved in plant growth promotion by directed evolution are yet to be understood. The present study aimed to understand the mechanism of stress management by a salt stress-acclimatized microbiome, generated through indirect plant-mediated selection over multiple plant ( Vigna radiata ) growth cycles, with a focus on the emission of volatile compounds. A culture bank was generated by isolation of bacterial strains from the stress-acclimatised microbiome, using group-specific media. Characterization of the strains was performed by examining their potential plant growth-promoting (PGP) traits followed by phylogenetic affiliation using 16S rRNA sequencing. The strains exhibited strong tolerance to salinity stress when grown on artificial root exudate medium and V8 medium, at different salt concentrations. Based on PGP scoring, the eleven best performing bacterial strains were assessed for their ability to impact plant morphology and growth attributes in a split plate assay allowing only volatile compounds to be exchanged, using Arabidopsis as a model plant. An alteration in the seedling morphology of Arabidopsis was observed due to the production of volatile bioactive compounds by some of the strains. To delineate the specific volatiles produced by the bacterial strains responsible for such an impact on Arabidopsis seedlings, the volatiles emitted by selected strains were collected and analyzed by GC-MS. A correlation could be drawn between the specific volatiles produced by key bacterial members of the acclimatized microbiome e.g. Bacillus haynesii, Pseudomonas monteilii and Ochrobactrum soli , and their contribution towards alleviation of salinity stress in A. thaliana . A detailed analysis of the volatilomes emitted by stress-acclimatized bacterial strains revealed the identity of crucial metabolites, for instance hydrocarbons like 7 methyl-hexadecane, 2-(2-butoxyethoxy) ethanol or sulfur containing volatiles, which could at least partially contribute to plant growth promotion and stress tolerance. This work opens up new avenues for rhizospheric engineering as a way towards more resilient and sustainable crop production. • Mode of action of engineered microbiome in stress mitigation revealed. • Strains with multi-PGP traits were identified from stress-acclimatized microbiome. • Bacteria exhibited salinity stress tolerance and growth promotion in Arabidopsis . • Volatiles’ importance in stress mitigation by acclimatised microbiome highlighted. • Key volatiles mediating growth promotion and stress tolerance were identified.