Browsing by Author "Jha, Prabhat Nath"

Now showing 1 - 20 of 29

ACC deaminase producing rhizobacterium Enterobacter cloacae ZNP-4 enhance abiotic stress tolerance in wheat plant
(PLOS Biology, 2022-05) Jha, Prabhat Nath
Plant growth promoting rhizobacterium (PGPR) designated as ZNP-4, isolated from the rhizosphere of Ziziphus nummularia, was identified as Enterobacter cloacae following 16S rRNA sequence analysis. The isolated strain exhibited various plant growth promoting (PGP) traits. The 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) activity was evaluated under diverse physiological conditions that could be useful for minimizing the abiotic stress-induced inhibitory effects on wheat plants. The strain showed resistance to salt (NaCl) and metal (ZnSO4) stress. The effect of E. cloacae ZNP-4 on the augmentation of plant growth was studied under salinity stress of 150 mM (T1 treatment) & 200 mM (T2 treatment) NaCl. The inoculation of strain ZNP-4 significantly improved the various growth parameters of wheat plant such as shoot length (41%), root length (31%), fresh weight (28%), dry weight (29%), photosynthetic pigments chlorophyll a (62%) and chlorophyll b (34%). Additionally, the strain was found to be efficient for minimizing the imposed Zn stress in terms of improving plant growth, biomass and photosynthetic pigments in pots containing different levels of metal stress of 150 mg kg-1 (treatment T1) and 250 mg kg-1 (treatment T2). Isolate ZNP-4 also improved the proline content and decreased malondialdehyde (MDA) level under both salinity and metal stress, therefore maintaining the membrane integrity. Furthermore, bacterial inoculation increased the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). The positive effects of PGPR occurred concurrently with the decrease in abiotic stress-induced reactive oxygen species (ROS) molecules such as hydrogen peroxide (H2O2) and superoxide (O2-) contents. Overall, the observed results indicate that use of bacteria with such beneficial traits could be used as bio-fertilizers for many crops growing under stress conditions.
Antibacterial, anti-biofilm and anti-virulence activity of biosynthesized silver nanoparticles against drug-resistant Staphylococcus aureus
(Springer, 2025-10) Jha, Prabhat Nath
Antibiotic resistance in bacteria has become a major concern for the effective treatment of infections; therefore, alternatives to antibiotics are being extensively researched to combat drug-resistant microbes. In this study, silver nanoparticles (AgNPs) were biosynthesized using aqueous extracts of papaya leaves (Carica papaya), cannabis leaves (Cannabis sativa), and cardamom (Elettaria cardamomum) and characterized by field-emission scanning electron microscopy (FE-SEM) and UV-visible spectrophotometry. Biosynthesized AgNPs were evaluated for their antibacterial, anti-biofilm, and anti-virulence potential by phenotypic and genotypic methods. AgNPs biosynthesized by all three extracts had spherical morphology and sizes in the nanoscale, average diameter ranging from 46.05 to 94.12 nm. Antibacterial susceptibility testing of S. aureus field isolates under study revealed 48% (24/50) and 38% (19/50) to be resistant to methicillin and amoxycillin-clavulanic acid, respectively. Antibacterial activity of biosynthesized AgNPs against S. aureus strains was determined by the well diffusion method. AgNPs were found to be effective on 90.90% (50/55) S. aureus strains with a zone of inhibition varying from 10 to 21 mm. The AgNPs were also found to be effective on other important bacterial pathogens (viz. Bacillus cereus ATCC 10876, Pseudomonas aeruginosa ATCC 27853, Salmonella Enteritidis ATCC 13070, Escherichia coli ATCC 43888, and Listeria monocytogenes MTCC 657) screened in the study with a ZOI of 15–18 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgNPs against S. aureus ranged between 0.015625-0.125 mg/mL and 0.015625-0.25 mg/mL, respectively. In the time kill assay, AgNPs were able to kill S. aureus rapidly within 0.5–1.0 h. In the haemolytic assay, 4–9% haemolysis was observed at concentrations ranging from 0.015625 to 0.25 mg/mL of AgNPs. Biofilm-forming ability of all strains of S. aureus (n = 55) determined by crystal violet assay revealed that 87.27% (48/55) were biofilm formers, while 12.73% (7/55) were non-biofilm formers. Out of 48 biofilm-forming strains, 81.25% (39/48) were strong biofilm producers, 10.41% (5/48) were moderate biofilm producers, and 8.33% (4/48) were weak biofilm producers. Anti-biofilm effect of AgNPs was found at sub-MIC (0.03125 mg/mL), phenotypically. Exopolysaccharide production was found to be reduced by 53.38% indicating the anti-virulence potential of AgNPs at sub-MIC. Relative expression analysis revealed that AgNPs downregulated the expression of biofilm-related genes, namely icaC, icaD, and spa, by 14.2, 10.6, and 8.7-fold, respectively, compared to the control at 3 h of incubation. Other biofilm-related and virulence genes, including icaA, icaB, icaR, agr, ebps, fnb-B, sar-A, and katA, were also found to be downregulated by 7.4, 7.5, 6.2, 5, 4.2, 7.3, 4, and 3.6-fold, respectively, at 3 h. All the target genes were also found to be downregulated at 24 h post-treatment with AgNPs, except icaD, icaR, and agr, which were slightly upregulated. In the present study, AgNPs were successfully biosynthesized and found to possess broad-spectrum antibacterial activity, reduce biofilm formation, and EPS production.
Biochemical and metabolic signatures are fundamental to drought adaptation in PGPR 2 Enterobacter bugandensis WRS7
(RSC, 2023-05) Jha, Prabhat Nath
Drought alone causes more annual loss in crop yield than the sum of all other environmental stresses. There is growing interest in harnessing the potential of stress-resilient PGPR in conferring plant resistance and enhancing crop productivity in drought-affected agroecosystems. A detailed understanding of the complex physiological and biochemical responses will open up the avenues to stress adaptation mechanisms of PGPR communities under drought. It will pave the way for rhizosphere engineering through metabolically engineered PGPR. Therefore, to reveal the physiological and metabolic networks in response to drought-mediated osmotic stress, we performed biochemical analyses and applied untargeted metabolomics to investigate the stress adaptation mechanisms of a PGPR Enterobacter bugendensis WRS7 (Eb WRS7). Drought caused oxidative stress and resulted in slower growth rates in Eb WRS7. However, Eb WRS7 could tolerate drought stress and did not show changes in cell morphology under stress conditions. Overproduction of ROS caused lipid peroxidation (increment in MDA) and eventually activated antioxidant systems and cell signalling cascades, which led to the accumulation of ions (Na+, K+, and Ca2+), osmolytes (proline, exopolysaccharides, betaine, and trehalose), and modulated lipid dynamics of the plasma membranes for osmosensing and osmoregulation, suggesting an osmotic stress adaption mechanism in PGPR Eb WRS7. Finally, GC–MS-based metabolite profiling and deregulated metabolic responses highlighted the role of osmolytes, ions, and intracellular metabolites in regulating Eb WRS7 metabolism. Our results suggest that understanding the role of metabolites and metabolic pathways can be exploited for future metabolic engineering of PGPR and developing bio inoculants for plant growth promotion under drought-affected agroecosystems.
Characterization of functional amyloid curli in biofilm formation of an environmental isolate Enterobacter cloacae SBP-8. Antonie Van Leeuwenhoek
(Springer, 2023-05) Jha, Prabhat Nath; Tare, Meghana
The biofilm formation by bacteria is a complex process that is strongly mediated by various genetic and environmental factors. Biofilms contribute to disease infestation, especially in chronic infections. It is, therefore important to understand the factors affecting biofilm formation. This study reports the role of a functional amyloid curli in biofilm formation at various abiotic surfaces, including medical devices, by an environmental isolate of Enterobacter cloacae (SBP-8) which has been known for its pathogenic potential. A knockout mutant of csgA, the gene encoding the major structural unit of curli, was created to study the effect of curli on biofilm formation by E. cloacae SBP-8. Our findings confirm the production of curli at 25 °C and 37 °C in the wild-type strain. We further investigated the role of curli in the attachment of E. cloacae SBP-8 to glass, enteral feeding tube, and foley latex catheter. Contrary to the previous studies reporting the curli production below 30 °C in the majority of biofilm-forming bacterial species, we observed its production in E. cloacae SBP-8 at 37 °C. The formation of more intense biofilm in wild-type strain on various surfaces compared to curli-deficient strain (ΔcsgA) at both 25 °C and 37 °C suggested a prominent role of curli in biofilm formation. Further, electron and confocal microscopy studies demonstrated the formation of diffused monolayers of microbial cells on the abiotic surfaces by ΔcsgA strain as compared to the thick biofilm by respective wild-type strain, indicating the involvement of curli in biofilm formation by E. cloacae SBP-8. Overall, our findings provide insight into biofilm formation mediated by curli in E. cloacae SBP-8. Further, we show that it can be expressed at a physiological temperature on all surfaces, thereby indicating the potential role of curli in pathogenesis
Characterizing the type 6 secretion system (T6SS) of E. cloacae SBP-8 and its role in pathogenesis and bacterial competition
(Elsevier, 2023-10) Jha, Prabhat Nath; Marathe, Sandhya
Despite the relevance of E. cloacae as an opportunistic pathogen, very little is known about its pathogenicity mechanism and the factors influencing its virulence. The mechanism of E. cloacae pathogenicity appears to be complex and multifactorial, with the presence of different putative virulence factors whose role is still not clear in the development of the disease. In this study, we systematically investigated the role of T6SS (type six secretion system) of E. cloacae SBP-8, an environmental isolate, in eukaryotic and bacterial cell interaction. Analysis of the genome sequence of E. cloacae SBP-8 revealed the presence of sets of genes coding for the expression of one complete T6SS cluster, which is similar to T6SS-1 cluster of E. cloacae ATCC 13047 (clinical isolates). In addition, an Hcp effector protein was detected in the secretome, and this secretion depended on ClpV, an Atpase of T6SS, confirming that strain SBP-8 produces functional T6SS. Deletion of T6SS-associated gene clpV did not induce any significant change in the life span and rate of colonization in C. elegans. No major significant change was observed in the expression profiling of antimicrobial genes (clec-60, clec-85, clec-87 and lys-1) and toll-like receptor (toll-1) gene, involved in stimulating an immune response against the pathogen. No difference in the ability to invade and proliferate in intestinal cells and phagocytosis by macrophages was observed. In addition, we demonstrated that the ability of E. cloacae SBP-8 to out-compete Escherichia coli was reliant upon its T6SS in contact-dependent manner. Our results show that T6SS of the environmental isolates is required for interbacterial competition but not for invasion and proliferation inside host cells.
Comparative analysis of defence responses Triticum aestivum L in response to the endophytic Pseudomonas aeruginosa PM389 and the non-host microbial pathogens Erwinia carotovora and Fusarium monaliforme
(World Researcher Association, 2022) Jha, Prabhat Nath
In the present study, Pseudomonas aeruginosa PM389 has been studied for comparing the defense responses in wheat plant against non-host pathogens Fusarium monaliforme and Erwinia caratovora. The comparative studies of defense enzymes produced on pretreatment of plants in the presence and absence of PM389 were also studied. Apart from it, disease incidence as well as plant growth promotion under in vitro and pot condition was recorded in the presence or absence of PM389 on challenging wheat plant with the non-host pathogen. Induction in all defense enzymes was observed on pretreatment of the plant with PM389 before pathogenic challenge with non-host. It was suggested that PM389 can generate induced systemic resistance in plants against pathogens. A less pathogenic population was recorded in the presence of PM389 than in its absence. In addition, it also showed plant growth promotion in the wheat under in vitro and pot studies. It was observed that PM389 was more effective against fungal pathogen than bacterial pathogen in both plant growth promotions as well as in decreasing disease incidence. Thus, PM389 can serve as a potential candidate as biofertilizer and biocontrol agent for non-host pathogens as well as having chances of cross-infection among various crops.
Drought-Tolerant Enterobacter bugandensis WRS7 Induces Systemic Tolerance in Triticum aestivum L. (Wheat) Under Drought Conditions
(Springer, 2023-07) Jha, Prabhat Nath
Some plant growth-promoting bacteria (PGPR) can ameliorate abiotic stressors like drought stress and promote plant growth. The present study investigated various drought-tolerant mechanisms of Enterobacter bugandensis WRS7, a rhizospheric isolate, by which it alleviates the deleterious effects of drought stress in wheat plants (Triticum aestivum L). The isolate WRS7 showed different plant growth-promoting properties, including nitrogen fixation, phosphate solubilization, siderophore production, phytohormone (indole acetic acid and gibberellic acid) production, exopolysaccharide secretion, and ACC deaminase activity. Its inoculation to wheat plants improved plant growth in terms of root/shoot growth and chlorophyll content. Its inoculation also exhibited drought stress ameliorating properties, including increased osmolyte content (proline and total soluble sugar), relative water content, catalase and superoxide dismutase activity, and decreased lipid peroxidation compared to non-inoculated plants. Our biochemical data were coherent with gene expression analysis of WRS7-treated plants, which showed altered expression of genes encoding antioxidant enzymes (CAT, APX, and GPX), osmolyte synthesis (P5CS, P5CR, and TPS1), biosynthesis of stress hormone genes (NCED, WZE, SAMS, ACS1, and ACO encoding proteins for the biosynthesis of abscisic acid and ethylene), and calcium transporter (TPC1) in the wheat plant. The regulation of the ethylene biosynthesis gene and modulation of TPC1 gene expression by PGPR E. bugandensis WRS7 in wheat plants highlights its additional role in alleviating drought stress. The colonization study demonstrated the successful colonization of E. bugandensis WRS7 in wheat plants. Overall, the present study indicates that E. bugandensis WRS7 alleviates drought stress in wheat plants by differentially regulating various metabolic genes in treated plants.
Electro-codeposited γ-Zn-Ni/Gr composite coatings: Effect of graphene concentrations in the electrolyte bath on tribo-mechanical, anti-corrosion and anti-bacterial properties
(Taylor & Francis, 2021-10) Jha, Prabhat Nath; Rathore, Jitendra S.; Belgamwar, Sachin U.
In this paper, low-cost and industrially scalable γ-Zn-Ni/Gr composite coatings were electro-codeposited from an acid-sulphate based electrolyte bath. The microstructure, morphology, composition, microhardness, wear performance, corrosion resistance and anti-bacterial properties of the composite coatings were investigated in detail and compared with a Zn-Ni alloy coating. The XRD diffraction peaks of prepared coatings confirm the presence of the γ phase of the Zn-Ni alloy. Results suggested that the addition of Gr effectively reduced the crystallite size and altered the morphology. As a result, the microhardness, wear performance and corrosion resistance were improved significantly. The γ-Zn-Ni/Gr composite coating prepared with 100 mg L−1 of Gr addition in the electrolyte bath displayed the highest microhardness of 243 HV and the lowest coefficient of friction of 0.32. The anti-bacterial activity tests confirmed that the γ-Zn-Ni/Gr composite coating (from the 100 mg L−1 bath) has the highest anti-bacterial activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).
Endophytic Bacteria Pseudomonas aeruginosa PM389 Subsists Host’s (Triticum aestivum) Immune Response for Gaining Entry Inside the Host
(JPAM, 2021) Jha, Prabhat Nath
The present study was designed to compare the defense response of the host plant towards endophytic bacteria Pseudomonas aeruginosa PM389 and pathogenic bacteria Erwinia carotovora and to correlate the level of defense enzymes vis-a-vis bacterial colonization in the host. Wheat seedlings were treated with 107-108 cells ml-1 endophytic and pathogenic bacteria in the separate experimental set-up, and the level of plant defense enzyme was measured at various time intervals. Comparatively reduced level of most defense enzymes was produced in endophytic bacteria treated plants. While the endophytic bacterial population was almost constant after 24 HAI (hour after inoculation), the population of pathogenic bacteria kept fluctuating during the study period from 24 HAI. Unlike pathogenic bacteria, we observed attenuated defense response in challenged host plants towards endophytic bacteria, which helps endophytes establish inside plant. This study would be useful for understanding the mechanism of colonization and strategies of endophytes to fight against the host defense response.
Endophytic Nitrogen-Fixing Bacteria as Biofertilizer
(Springer, 2012) Panwar, Jitendra; Jha, Prabhat Nath
Evaluation of biphenyl- and polychlorinated-biphenyl (PCB) degrading Rhodococcus sp. MAPN-1 on growth of Morus alba by pot study
(Taylor & Francis, 2020-06) Paul, Atish Tulshiram; Jha, Prabhat Nath
This study focused on isolation of bacteria with biphenyl/polychlorinated biphenyl (PCB) degrading ability from the rhizosphere of Morus alba (mulberry plant). Repetitive enrichment of rhizospheric soil samples with biphenyl resulted in the isolation of Rhodococcus sp. MAPN-1, identified by 16S rRNA gene sequence analysis. The bacterium showed growth on five different aromatic compounds (naphthalene, salicylic acid, benzoic acid, dibenzofuran and anthracene). Benzoic acid was detected as the major metabolite during biphenyl degradation using high-performance thin-layer chromatography (HPTLC) with Rf 0.42 at 254 nm. Further GC-MS/MS study showed 95% and 15% degradation of biphenyl and dichlorobiphenyl, respectively. A pot study was conducted to evaluate the effect of presence of biphenyl on M. alba and the role of biphenyl degrader Rhodococcus sp. MAPN-1 in relation to phytoremediation. Morus alba twigs in biphenyl spiked soil (100 mg/kg and 300 mg/kg) inoculated with Rhodococcus sp. MAPN-1 showed growth, whereas, growth of plants (control) was adversely affected in biphenyl-spiked uninoculated soil. It is the first report of isolation of Rhodococcus sp. MAPN-1 from the rhizosphere of Morus alba, its capability to degrade biphenyl, thereby showing a positive effect on the plant growth grown in biphenyl spiked soil.
Exploring Functional Diversity and Community Structure of Diazotrophic Endophytic Bacteria Associated with Pennisetum glaucum Growing under Field in a Semi-Arid Region
(MDPI, 2022-06) Jha, Prabhat Nath
Diazotrophic endophytic bacteria (DEB) are the key drivers of nitrogen fixation in rainfed soil ecosystems and, hence, can influence the growth and yield of crop plants. Therefore, the present work investigated the structure and composition of the DEB community at different growth stages of field-grown pearl millet plants, employing the cultivation-dependent method. Diazotrophy of the bacterial isolates was confirmed by acetylene reduction assay and amplification of the nifH gene. ERIC-PCR-based DNA fingerprinting, followed by 16S rRNA gene analysis of isolates recovered at different time intervals, demonstrated the highest bacterial diversity during early (up to 28 DAS (Days after sowing)) and late (63 DAS onwards) stages, as compared to the vegetative growth stage (28–56 DAS). Among all species, Pseudomonas aeruginosa was the most dominant endophyte. Assuming modulation of the immune response as one of the tactics for successful colonization of P. aeruginosa PM389, we studied the expression of the profile of defense genes of wheat, used as a host plant, in response to P. aeruginosa inoculation. Most of the pathogenesis-related PR genes were induced initially (at 6 h after infection (HAI)), followed by their downregulation at 12 HAI. The trend of bacterial colonization was quantified by qPCR of 16S rRNAs. The results obtained in the present study indicated an attenuated defense response in host plants towards endophytic bacteria, which is an important feature that helps endophytes establish themselves inside the endosphere of roots.
Facile and Scalable Co-deposition of Anti-bacterial Zn-GNS Nanocomposite Coatings for Hospital Facilities: Tribo-Mechanical and Anti-corrosion Properties
(Springer, 2021-10) Rathore, Jitendra S.; Jha, Prabhat Nath; Belgamwar, Sachin U.
Frequently touched surfaces in the hospital environment act as a reservoir for the bacteria responsible for healthcare-associated infections (HCAIs). In this study, graphene nanosheets (GNS) were incorporated into a low-cost Zn coating using electrochemical co-deposition (ECD) to prevent HCAIs. The effects of different concentrations of GNS in the ECD bath (25 mg/L, 50 mg/L and 100 mg/L) were evaluated in detail for microstructural, tribo-mechanical, surface wetting, anti-corrosion, and anti-bacterial features of coatings. The microhardness, friction coefficient, wear loss, and polarization resistance values were remarkably improved from 77 HV, 0.7 mg, 26.1 mg and 13.68 kΩ cm2 mg for the pure Zn coating to 151 HV, 0.48 mg, 12.09 mg and 2.3 kΩ cm2 for the Zn-GNS (100 mg/L) nanocomposite coating, respectively. The anti-bacterial activities of the coatings were enhanced with the increase in GNS concertation in the ECD bath and Zn-GNS (100 mg/L) nanocomposite coating exhibited inhibition zones of 22 mm and 25 mm against Staphylococcus aureus and Escherichia coli bacteria.
Fluorescent glutamine and asparagine as promising probes for chemical biology
(RSC, 2021) Sakhuja, Rajeev; Jha, Prabhat Nath; Kumar, Dalip
Fluorescent probes have become valuable tools in chemical biology, providing interesting inferences for unfolding the complexities of natural biochemical processes. In this study, we report the synthesis and characterization of fluorescent labelled glutamine (Gln) and asparagine (Asn) derivatives via traceless Staudinger ligation, which exhibited high fluorescence quantum yields, excellent photostabilities and emission of blue fluorescence in the visible region. The successful permeation of these fluorescent amino acids into cellular components proved their potential as fluorescent probes for chemical biology.
Insights Into the Dynamics and Composition of Biofilm Formed by Environmental Isolate of Enterobacter cloacae
(Frontiers, 2022-07) Jha, Prabhat Nath; Tare, Meghana
Bacterial biofilms are clinically admissible and illustrate an influential role in infections, particularly those related to the implant of medical devices. The characterization of biofilms is important to understand the etiology of the diseases. Enterobacter cloacae are known for causing infections by forming biofilms on various abiotic surfaces, such as medical devices. However, a detailed characterization in terms of morphology and the molecular composition of the formed biofilms by this bacterium is sparse. The present study provides insights into the biofilm formation of E. cloacae SBP-8, an environmental isolate, on various surfaces. We performed assays to understand the biofilm-forming capability of the SBP-8 strain and characterized the adhering potential of the bacteria on the surface of different medical devices (foley latex catheter, enteral feeding tube, and glass) at different temperatures. We found that medical devices exhibited strong colonization by E. cloacae SBP-8. Using field emission-scanning electron microscopy (FE-SEM) studies, we characterized the biofilms as a function of time. It indicated stronger biofilm formation in terms of cellular density and EPS production on the surfaces. Further, we characterized the biofilm employing surface-enhanced Raman spectroscopy (SERS) and identified the vast heterogenic nature of the biofilm-forming molecules. Interestingly, we also found that this heterogeneity varies from the initial stages of biofilm formation until the maturation and dispersion. Our studies provide insights into biofilm composition over a period of time, which might aid in understanding the biofilm dispersion phases, to enhance the presently available treatment strategies.
Integrated metabolomic, molecular, and morphological insights into the degradation of polychlorinated biphenyls (PCB) by priestia megaterium mapb-27
(ACS, 2025-10) Paul, Atish Tulshiram; Jha, Prabhat Nath
Polychlorinated biphenyls (PCBs) are persistent organic pollutants that cause profound deleterious effects on the environment and human health. Exposure to PCBs and biphenyl can induce changes in cellular metabolite levels. However, metabolic responses to utilize and adapt to PCBs are not well understood. Therefore, this study meticulously examined the PCB degradation potential, gene expression, and metabolic responses of Priestia megaterium MAPB-27 exposed to biphenyl. MAPB-27 showed growth and chemotaxis toward PCB degradation intermediates such as biphenyl, dihydroxy biphenyl, benzoate, and catechol. We employed GC-MS/MS to elucidate disparities in the main metabolic pathways in the biphenyl-exposed MAPB-27 through variations in metabolite composition and PCB biodegradation, while Field-emission scanning electron microscopy (FESEM) was used to study cell morphology. GC-MS/MS analysis highlighted the degradation of trichlorobiphenyl, tetrachlorobiphenyl, pentachlorobiphenyl, and hexachlorobiphenyl by P. megaterium MAPB-27, exhibiting 92.5, 62.9, 3.7, and 2.4%, respectively. GC-MS/MS analysis identified 4-dihydroxy-2-oxo-valerate, benzoic acid, and 2,3-dihydroxybenzoic acid as the major degradative metabolites in MAPB-27. MAPB-27 extract also contains metabolites with a wide range of direct industrial applications, such as poly(3-hydroxybutyrate) (3-hydroxybutyrate), a biobased organic acid (3-hydroxypropionoic acid), and antibacterial and antifungal compounds (phenyllactic acid, 4-hydroxyphenyllactic acid, and β-sitosterol). Glyoxylate and dicarboxylate metabolism and fatty acid biosynthesis were observed to be the active metabolisms in MAPB-27 grown in biphenyl-supplemented Minimal Medium. Overall, the results of this study provided important insights into microbial adaptation to biphenyl and the biodegradation of PCB. Thus, the P. megaterium MAPB-27 strain can be used for the development of efficient PCB biodegradation strategies and for the exploration of industrial applications.
Mechanistic insights on plant root colonization by bacterial endophytes: a symbiotic relationship for sustainable agriculture
(Springer, 2018) Panwar, Jitendra; Jha, Prabhat Nath
Plant–microbe and soil interactions are one of the oldest muse for multi-disciplinary researchers. Plant growth promoting microorganisms influence the host physiology by secreting regulatory chemical signals in the vicinity of plant roots and play a key role in the enhancement of plant growth and expansion. The present review deals with the in-depth understanding of steps involved in host tissues colonization by bacterial endophytes. The molecular insights of these events, particularly for endophytic bacteria, are poorly documented till date. The endophytic bacteria must coexist with the host plant and capable of colonizing the internal plant tissues without being recognized as a pathogen. A proper understanding of exchange of signals between the host plant and bacterial communities is required which may facilitate the development of new strategies to promote beneficial interactions between them. This knowledge can be instrumental in agricultural practices as well as for phytoremediation of pollutants. Keeping these facts in mind, the present review attempts to explore the systematic understanding of steps involved and molecular insights of plant colonization events by endophytic bacteria. We conclude that molecular mechanisms and factors affecting endophytic bacterial colonization deserve more research attention in order to exploit their beneficial aspects for sustainable agriculture and environment.
Metabolomic profiling of biphenyl-induced stress response of Brucella anthropi MAPB-9
(Springer Nature, 2025-04) Jha, Prabhat Nath; Paul, Atish Tulshiram
The exposure of bacteria to toxic compounds such as polychlorinated biphenyl (PCB) and biphenyl induces an adaptive response at different levels of cell morphology, biochemistry, and physiology. PCB and biphenyl are highly toxic compounds commercially used in the industry. In our previous study, Brucella anthropi MAPB-9 efficiently degraded PCB-77 and biphenyl at a high concentration. In this study, we used metabolomic analyses to understand the metabolic processes occurring in MAPB-9 during exposure to biphenyl. A combination of analytical techniques such as GC-MS/MS and HR-MS study confirmed the complete biphenyl degradation pathway. The intermediate metabolic products identified were cis-2, 3-dihydro-2, 3-dihydroxy biphenyl, 2,3-dihydroxy biphenyl, and 4-dihydroxy-2-oxo-valerate. Further, benzoic acid and 2,3-dihydroxy benzoic acid metabolites identified in the extract revealed the interconnection of biphenyl and benzoic degradation pathways. In addition, the variations in the functioning of the major biochemical pathways in the cells were revealed through changes in the profile of metabolites belonging to glyoxylate, tricarboxylic acid (TCA) cycle, and fatty acid pathways. The exposure to biphenyl inhibited metabolic activity leading to changes in the morphology and metabolism. Despite many adverse changes, the MAPB-9 was able to adapt and grow in the toxic environment undergoing upper and lower biphenyl degradation pathways.
Metagenomic analysis for taxonomic and functional potential of Polyaromatic hydrocarbons (PAHs) and Polychlorinated biphenyl (PCB) degrading bacterial communities in steel industrial soil
(PLOS, 2022-04) Paul, Atish Tulshiram; Jha, Prabhat Nath
Iron and steel industries are the major contributors to persistent organic pollutants (POPs). The microbial community present at such sites has the potential to remediate these contaminants. The present study highlights the metabolic potential of the resident bacterial community of PAHs and PCB contaminated soil nearby Bhilai steel plant, Chhattisgarh (India). The GC-MS/MS analysis of soil samples MGB-2 (sludge) and MGB-3 (dry soil) resulted in identification of different classes of POPs including PAHs {benzo[a]anthracene (nd; 17.69%), fluorene (15.89%, nd), pyrene (nd; 18.7%), benzo(b)fluoranthene (3.03%, nd), benzo(k)fluoranthene (11.29%; nd), perylene (5.23%; nd)} and PCBs (PCB-15, PCB-95, and PCB-136). Whole-genome metagenomic analysis by Oxford Nanopore GridION Technology revealed predominance of domain bacteria (97.4%; 97.5%) followed by eukaryote (1.4%; 1.5%), archaea (1.2%; 0.9%) and virus (0.02%; 0.04%) in MGB-2 and MGB-3 respectively. Proteobacteria (44.3%; 50.0%) to be the prominent phylum followed by Actinobacteria (22.1%; 19.5%) in MBG-2 and MBG-3, respectively. However, Eukaryota microbial communities showed a predominance of phylum Ascomycota (20.5%; 23.6%), Streptophyta (18.5%, 17.0%) and unclassified (derived from Eukaryota) (12.1%; 12.2%) in MGB-2 and MGB-3. The sample MGB-3 was richer in macronutrients (C, N, P), supporting high microbial diversity than MGB-2. The presence of reads for biphenyl degradation, dioxin degradation, PAH degradation pathways can be further correlated with the presence of PCB and PAH as detected in the MGB-2 and MGB-3 samples. Further, taxonomic vis-à-vis functional analysis identified Burkholderia, Bradyrhizobium, Mycobacterium, and Rhodopseudomonas as the keystone degrader of PAH and PCB. Overall, our results revealed the importance of metagenomic and physicochemical analysis of the contaminated site, which improves the understanding of metabolic potential and adaptation of bacteria growing under POP contaminated environments.
PCB-77 biodegradation potential of biosurfactant producing bacterial isolates recovered from contaminated soil
(Frontiers, 2022-09) Paul, Atish Tulshiram; Jha, Prabhat Nath
Polychlorinated biphenyls (PCBs) are persistent organic pollutants widely distributed in the environment and possess deleterious health effects. The main objective of the study was to obtain bacterial isolates from PCB-contaminated soil for enhanced biodegradation of PCB-77. Selective enrichment resulted in the isolation of 33 strains of PCB-contaminated soil nearby Bhilai steel plant, Chhattisgarh, India. Based on the prominent growth using biphenyl as the sole carbon source and the confirmation of its degradation by GC-MS/MS analysis, four isolates were selected for further study. The isolates identified by 16S rRNA gene sequencing were Pseudomonas aeruginosa MAPB-2, Pseudomonas plecoglossicida MAPB-6, Brucella anthropi MAPB-9, and Priestia megaterium MAPB-27. The isolate MAPB-9 showed a degradation of 66.15% biphenyl, while MAPB-2, MAPB-6, and MAPB-27 showed a degradation of 62.06, 57.02, and 56.55%, respectively in 48 h. Additionally, the degradation ability of these strains was enhanced with addition of co-metabolite glucose (0.2%) in the culture medium. Addition of glucose showed 100% degradation of biphenyl by MAPB-9, in 48 h, while MAPB-6, MAPB-2, and MAPB-27 showed 97.1, 67.5, and 53.3% degradation, respectively as analyzed by GC-MS/MS. Furthermore, in the presence of inducer, PCB-77 was found to be 59.89, 30.49, 27.19, and 4.43% degraded by MAPB-6, MAPB-9, MAPB-2, and MAPB-27, respectively in 7 d. The production of biosurfactants that aid in biodegradation process were observed in all the isolates. This was confirmed by ATR-FTIR analysis that showed the presence of major functional groups (CH2, CH3, CH, = CH2, C–O–C, C-O) of the biosurfactant. The biosurfactants were further identified by HPTLC and GC-MS/MS analysis. Present study is the first to report PCB-77 degradation potential of Pseudomonas aeruginosa, B. anthropi, Pseudomonas plecoglossicida, and Priestia megaterium. Similarly, this is the first report on Pseudomonas plecoglossicida and Priestia megaterium for PCB biodegradation. Our results suggest that the above isolates can be used for the biodegradation of biphenyl and PCB-77 in PCB-contaminated soil.