Mycobacterium Gilvum Research Articles

Distribution patterns and influential factors of pathogenic bacteria in freshwater aquaculture sediments.

Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal-Wallis H test, except for Mycobacterium gilvum, there were significant differences (P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili, HSI-I, Alginate, Colibactin, and Capsule. According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs (R = 0.82, P < 0.01), and in particular, plasmids (R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.

Metagenomics reveals mechanism of pyrene degradation by an enriched bacterial consortium from a coking site contaminated with PAHs

A bacterial consortium, termed WPB, was obtained from polycyclic aromatic hydrocarbons (PAHs) contaminated soil from a coking site. The consortium effectively degraded 100 mg L−1 pyrene by 94.8 % within 12 days. WPB was also able to degrade phenanthrene (98.3 %) and benzo[a]pyrene (24.6 %) in 12 days, while the individual isolates showed no PAHs degrading ability. Paracoccus sp. dominated the bacterial consortium (65.0–86.2 %) throughout the degradation process. Metagenomic sequencing reveals the proportion of sequences with xenobiotics biodegradation and metabolism increased throughout the degradation process indicating the great potential of WPB to degrade pollutants. The annotation of genes by metagenomic analysis help reconstruct the degradation pathways (“phthalate pathway” and “naphthalene degradation”) and reveal how different bacteria contribute to the degradation process. Mycobacterium gilvum was found to carry nidAB genes that catalyze the first step of high-molecular-weight (HMW) PAHs in the degradation process despite Mycobacterium gilvum accounting for only 0.005–0.06 %. In addition, genomes of Paracoccus denitrificans and some other genera affiliated with Devosia, Pusillimonas caeni and Eoetvoesia caeni were successfully recovered and were found to carry genes responsible for the degradation of the intermediates of pyrene. These results enable further understanding of the metabolic patterns of pyrene-degrading consortia and provide direction for further cultivation and discovery of key players in complex microbial consortia.

Enhanced Bioremediation of Aged Polycyclic Aromatic Hydrocarbons in Soil Using Immobilized Microbial Consortia Combined with Strengthening Remediation Strategies.

Microbial biodegradation is considered as one of the most effective strategies for the remediation of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). To improve the degradation efficiency of PAHs, PAH-degrading consortia combined with strengthening remediation strategies was used in this study. The PAH biodegrading performance of seven bacterial consortia constructed by different ratios of Mycobacterium gilvum MI, Mycobacterium sp. ZL7 and Rhodococcus rhodochrous Q3 was evaluated in an aqueous system containing phenanthrene, pyrene, benzo[a]pyrene and benzo[b]fluoranthene. Bacterial consortium H6 (Q3:ZL7:MI = 1:2:2) performed a high degrading efficiency of 59% in 8 days. The H6 was subsequently screened to explore its potential ability and performance to degrade aged PAHs in soils from a coking plant and the effects of strengthening strategies on the aged PAH degradation, including the addition of glucose or sodium dodecyl benzene sulfonate (SDBS) individually or as a mixture along immobilization of the inoculant on biochar. The highest degradation efficiencies, which were 15% and 60% for low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs, respectively, were observed in the treatment using immobilized microbial consortium H6 combined with the addition of glucose and SDBS after 24 days incubation. This study provides new insights and guidance for future remediation of aged PAH contaminated soils.

Chemotactic Bacteria Facilitate the Dispersion of Nonmotile Bacteria through Micrometer-Sized Pores in Engineered Porous Media.

Recent research has demonstrated that chemotactic bacteria can disperse inside microsized pores while traveling toward favorable conditions. Microbe–microbe cotransport might enable nonmotile bacteria to be carried with motile partners to enhance their dispersion and reduce their deposition in porous systems. The aim of this study was to demonstrate the enhancement in the dispersion of nonmotile bacteria (Mycobacterium gilvum VM552, a polycyclic aromatic hydrocarbon-degrader, and Sphingobium sp. D4, a hexachlorocyclohexane-degrader, through micrometer-sized pores near the exclusion-cell-size limit, in the presence of motile Pseudomonas putida G7 cells. For this purpose, we used bioreactors equipped with two chambers that were separated with membrane filters with 3, 5, and 12 μm pore sizes and capillary polydimethylsiloxane (PDMS) microarrays (20 μm × 35 μm × 2.2 mm). The cotransport of nonmotile bacteria occurred exclusively in the presence of a chemoattractant concentration gradient, and therefore, a directed flow of motile cells. This cotransport was more intense in the presence of larger pores (12 μm) and strong chemoeffectors (γ-aminobutyric acid). The mechanism that governed cotransport at the cell scale involved mechanical pushing and hydrodynamic interactions. Chemotaxis-mediated cotransport of bacterial degraders and its implications in pore accessibility opens new avenues for the enhancement of bacterial dispersion in porous media and the biodegradation of heterogeneously contaminated scenarios.

Differences in the properties of extracellular polymeric substances responsible for PAH degradation isolated from Mycobacterium gilvum SN12 grown on pyrene and benzo[a]pyrene.

This study aimed to evaluate the differences in the characteristics of extracellular polymeric substances (EPSs) secreted by Mycobacterium gilvum SN12 (M.g. SN12) cultured on pyrene (Pyr) and benzo[a]pyrene (BaP). A heating method was used to extract EPSs from M.g. SN12, and the composition, emulsifying activity, and morphology of EPS extracts were investigated. Results showed that EPS extracts varied significantly with Pyr or BaP addition to the bacterial cultures. The concentration of proteins and carbohydrates, the main components of the EPS extracts, first increased and then decreased, with an increase in the concentration of Pyr (0-120mg L-1) and BaP (0-120mg L-1). A similar trend was observed for the emulsifying activity of the EPS extracts. EPSs extracted from all cultures exhibited a compact structure with a smooth surface, except for EPSs extracted from BaP-grown M.g. SN12, which revealed a more fragile and softer surface. These findings suggest that Pyr and BaP had different influences on the properties of isolated EPSs, providing insights into the mechanism underlying polycyclic aromatic hydrocarbons (PAHs) biodegradation by some EPS-secreting bacteria. To the best of our knowledge, this is the first report on the texture profile of EPS samples extracted from M.g. SN12 grown on PAHs.

Microbial degradation of pyrene in holm oak (Quercus ilex) phyllosphere: Role of particulate matter in regulating bioaccessibility

In this study we first measured the mineralization of pyrene on leaves of urban holm oak (Quercus ilex) by autochthonous microorganisms and an inoculated PAH degrading bacterium (i.e., Mycobacterium gilvum), selected as a model phyllosphere species, as well as the leaf-water (KLW) and leaf-air (KLA) partition coefficients for this chemical. Mineralization was investigated in two different experimental systems in terms of leaf and microorganism environment. Additionally, the influence on pyrene partitioning and mineralization when particulate matter (PM) was present on the leaf surface or removed was studied. Mineralization of 14C-labeled pyrene by autochthonous microorganisms was lower than 1% after approximately two weeks, while M. gilvum mineralized 5% to 17% of pyrene. These extents corresponded to mineralization half-lives that ranged between ~30 to ~200 days. We proposed that PM present at the leaf surface reduced the accumulation of pyrene by inner compartments (cuticle) distantly located from microbial cells and enhanced the bioaccessibility of pyrene, speeding up microbial activity and therefore mineralization. These results highlight that plant-phyllosphere microorganism interaction is more complex than currently established and deserves additional studies to further comprehend the air purification ecosystem service of phyllosphere microorganisms.

Pyrene Degradation by Mycobacterium gilvum: Metabolites and Proteins Involved

Polycyclic aromatic hydrocarbons (PAHs) are toxic organic pollutants and omnipresent in the aquatic and terrestrial ecosystems. A high-efficient pyrene-degrading strain CP13 was isolated from activated sludge and identified as Mycobacterium gilvum based on the analysis of 16S rRNA gene sequence. More than 95% of pyrene (50 mg L−1) was removed by CP13 within 7 days under the alkaline condition. Pyrene metabolites, including 4-phenanthrenecarboxylic acid, 4-phenanthrenol, 1-naphthol, and phthalic acid, were detected and characterized by GC-MS. Results suggested that pyrene was initially attacked at positions C-4 and C-5, then followed by ortho cleavage, and further degraded following the phthalate metabolic pathway. Analysis of pyrene-induced proteins showed that the extradiol dioxygenase, a key enzyme involved in pyrene degradation, was highly up-regulated in pH 9 incubation condition, which illustrated the high efficiency of CP13 under alkaline environment. The present study demonstrated that the isolated bacterial strain CP13 is a good candidate for bioremediation of alkaline PAH-contaminated sites.

Mycelium-Enhanced Bacterial Degradation of Organic Pollutants under Bioavailability Restrictions.

This work examines the role of mycelia in enhancing the degradation by attached bacteria of organic pollutants that have poor bioavailability. Two oomycetes, Pythium oligandrum and Pythium aphanidermatum, were selected as producers of mycelial networks, while Mycobacterium gilvum VM552 served as a model polycyclic aromatic hydrocarbon (PAH) degrading bacterium. The experiments consisted of bacterial cultures exposed to a nondisturbed nonaqueous phase liquid (NAPL) layer containing a heavy fuel spiked with 14C-labeled phenanthrene that were incubated in the presence or absence of the mycelia of the oomycetes in both shaking and static conditions. At the end of the incubation, the changes in the total alkane and PAH contents in the NAPL residue were quantified. The results revealed that with shaking and the absence of mycelia, the strain VM552 grew by utilizing the bulk of alkanes and PAHs in the fuel; however, biofilm formation was incipient and phenanthrene was mineralized following zero-order kinetics, due to bioavailability limitations. The addition of mycelia favored biofilm formation and dramatically enhanced the mineralization of phenanthrene, up to 30 times greater than the rate without mycelia, possibly by providing a physical support to bacterial colonization and by supplying nutrients at the NAPL/water interface. The results in the static condition were very different because the bacterial strain alone degraded phenanthrene with sigmoidal kinetics but could not degrade alkanes or the bulk of PAHs. We suggest that bacteria/oomycete interactions should be considered not only in the design of new inoculants in bioremediation but also in biodegradation assessments of chemicals present in natural environments.

Evaluation of PyroMark Q24 pyrosequencing as a method for the identification of mycobacteria

We evaluated PyroMark Q24 (QIAGEN) pyrosequencing as a method for the identification of mycobacteria, with potential application in clinical practice. Sequence data from the hypervariable region A of the 16S rRNA gene (43 and 35bp sequences) were obtained using PyroMark Q24, and a similarity search was performed automatically with PyroMark IdentiFire software. Of the 148 mycobacterial type strains tested, 138 (93.2%) were accurately identified to single or clade species level, including complex level. From the remaining 10 strains, 3 (Mycobacterium gilvum, Mycobacterium goodi, and Mycobacterium thermoresistible) showed poor sequencing quality of homopolymers. For 6 other strains (Mycobacterium cosmeticum, Mycobacterium flavescens, Mycobacterium pallens, Mycobacterium hodleri, Mycobacterium xenopi, and Mycobacterium crocinum), the sequences were unreadable from the middle, and Sanger sequencing indicated biallelic site. Finally, a 40bp sequence for Mycobacterium gordonae could not be obtained despite repeated attempts. PyroMark Q24 provided accurate identification of multiple mycobacterial strains isolated from common clinical settings, but additional gene sequencing is required to distinguish species identified as a group or complex.

Extracellular Polymeric Substances from a Fungus Are More Effective than Those from a Bacterium in Polycyclic Aromatic Hydrocarbon Biodegradation

To investigate the differential contribution of extracellular polymeric substances (EPS) to polycyclic aromatic hydrocarbon (PAH) degradation by fungi and bacteria, the PAH-degrading ability and characteristics of EPS from the bacterium Mycobacterium gilvum SN12 and the fungus Mucor mucedo were compared. The fungus degraded 11% more pyrene and 21% more benzo[a]pyrene (B[a]P) than the bacterium. The biodegradation of pyrene and B[a]P increased after EPS were introduced into the PAH degradation solution, and 5.0% more pyrene and 4.5% more B[a]P were achieved for the added EPS from the fungal compared with the bacterial isolate. The comparison of two EPS indicated that the amount of protein and carbohydrate in EPS from the fungus was greater than that from the bacterium and was especially enriched for tryptophan, which is positively related to the increase of PAH biodegradation by fungal EPS. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) further revealed that higher molecular weight (HMW) of proteins over 200 kDa only existed in EPS from the fungus, and the polymorphism of proteins in EPS from the fungus was more abundant than that from the bacterium. The HMW proteins with stronger hydrophobicity in the fungal EPS also enabled the fungus to absorb more PAH than the bacterium. The results demonstrated that the pronounced differences in the characteristics of EPS from the fungal and the bacterial sources are responsible for the differential effects on PAH biodegradation.

Enhanced biodegradation of PAHs in historically contaminated soil by M. gilvum inoculated biochar

The inoculation of rice straw biochar with PAH-degrading Mycobacterium gilvum (1.27 × 1011 ± 1.24 × 1010 cell g−1), and the subsequent amendment of this composite material to PAHs contaminated (677 mg kg−1) coke plant soil, was conducted in order to investigate if would enhance PAHs biodegradation in soils. The microbe-biochar composite showed superior degradation capacity for phenanthrene, fluoranthene and pyrene. Phenanthrene loss in the microbe-biochar composite, free cell alone and biochar alone treatments was, respectively, 62.6 ± 3.2%, 47.3 ± 4.1% and non-significant (P > 0.05); whereas for fluoranthene loss it was 52.1 ± 2.3%; non-significant (P > 0.05) and non-significant (P > 0.05); and for pyrene loss it was 62.1 ± 0.9%; 19.7 ± 6.5% and 13.5 ± 2.8%. It was hypothesized that the improved remediation was underpinned by i) biochar enhanced mass transfer of PAHs from the soil to the carbonaceous biochar “sink”, and ii) the subsequent degradation of the PAHs by the immobilized M. gilvum. To test this mechanism, a surfactant (Brij 30; 20 mg g−1 soil), was added to impede PAHs mass transfer to biochar and sorption. The surfactant increased solution phase PAH concentrations and significantly (P < 0.05) reduced PAH degradation in the biochar immobilized M. gilvum treatments; indicating the enhanced degradation occurred between the immobilized M. gilvum and biochar sorbed PAHs.

Bioremediation of PAH-contaminated farmland: field experiment.

The agricultural soil contaminated by polycyclic aromatic hydrocarbons (PAHs) is gradually emerging and becoming serious in China with the rapid development of economy. To reduce the risk of PAHs in agricultural soil and guarantee the food safety, the biological agent that Mycobacterium gilvum immobilized on modified peanut shell powder enhanced remediation of polycyclic aromatic hydrocarbon-contaminated vegetable farmland was investigated under the conditions of the field experiment. The results indicated that adding biological agent could promote PAH degradation in the soil, especially high-ring PAHs. The degradation rates of PAHs in the soil could be further improved to 16.5-43.5%, respectively, compared with the soil without the biological agent. Adding the biological agent could significantly improve soil dehydrogenase activity and microbial diversity. It also could reduce the enrichment of PAHs in mustard planted in the polluted field, which indicated that the biological treatments might be less ecological risk. The work suggested that adding the biological agent might be a promising in situ bioremediation strategy for PAH-contaminated farmland field.

Mobilization of Pollutant-Degrading Bacteria by Eukaryotic Zoospores.

The controlled mobilization of pollutant-degrading bacteria has been identified as a promising strategy for improving bioremediation performance. We tested the hypothesis whether the mobilization of bacterial degraders may be achieved by the action of eukaryotic zoospores. We evaluated zoospores that are produced by the soil oomycete Pythium aphanidermatum as a biological vector, and, respectively, the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria Mycobacterium gilvum VM552 and Pseudomonas putida G7, acting as representative nonflagellated and flagellated species. The mobilization assay was performed with a chemical-in-capillary method, in which zoospores mobilized bacterial cells only when they were exposed to a zoospore homing inducer (5% (v/v) ethanol), which caused the tactic response and settlement of zoospores. The mobilization was strongly linked to a lack of bacterial motility, because the nonflagellated cells from strain M. gilvum VM552 and slightly motile, stationary-phase cells from P. putida G7 were mobilized effectively, but the actively motile, exponentially grown cells of P. putida G7 were not mobilized. The computer-assisted analysis of cell motility in mixed suspensions showed that the swimming rate was enhanced by zoospores in stationary, but not in exponentially grown, cells of P. putida G7. It is hypothesized that the directional swimming of zoospores caused bacterial mobilization through the thrust force of their flagellar propulsion. Our results suggest that, by mobilizing pollutant-degrading bacteria, zoospores can act as ecological amplifiers for fungal and oomycete mycelial networks in soils, extending their potential in bioremediation scenarios.

Enhanced biodegradation of pyrene by immobilized bacteria on modified biomass materials

The degradation of pyrene (PYR) by Mycobacterium gilvum immobilized on peanut shell powder (PSP) was improved by chemically modifying the PSP. The physicochemical properties of the modified biomass (M-PSP) were characterized with surface area analysis, X-ray diffraction, Fourier transform infrared and solid-state CP/MAS 13C NMR spectra. The results showed that the chemical modification decreased the crystallinity of the biomass and destroyed the benzene rings in the cellulose, which improved the porosity of PSP. Fluorescein diacetate activity (FDA) of cells immobilized on the M-PSP decreased more slowly than cells immobilized on PSP. The PYR degradation efficiencies achieved by bacteria immobilized on M-PSP was higher than that achieved by immobilized bacteria on PSP after 7 d. It revealed that chemical modification of biomass could further improve bacterial activity and enhance the degradation ability of the cells compared with the raw one, as we expected.In summary, this study shows that M-PSP is a good immobilizing bio-mass for supporting pollutant-degrading bacteria and could be employed as an effective material for PYR biodegradation.

Surface tailored organobentonite enhances bacterial proliferation and phenanthrene biodegradation under cadmium co-contamination

Co-contamination of soil and water with polycyclic aromatic hydrocarbon (PAH) and heavy metals makes biodegradation of the former extremely challenging. Modified clay-modulated microbial degradation provides a novel insight in addressing this issue. This study was conducted to evaluate the growth and phenanthrene degradation performance of Mycobacterium gilvum VF1 in the presence of a palmitic acid (PA)-grafted Arquad® 2HT-75-based organobentonite in cadmium (Cd)-phenanthrene co-contaminated water. The PA-grafted organobentonite (ABP) adsorbed a slightly greater quantity of Cd than bentonite at up to 30mgL−1 metal concentration, but its highly negative surface charge imparted by carboxylic groups indicated the potential of being a significantly superior adsorbent of Cd at higher metal concentrations. In systems co-contained with Cd (5 and 10mgL−1), the Arquad® 2HT-75-modified bentonite (AB) and PA-grafted organobentonite (ABP) resulted in a significantly higher (72–78%) degradation of phenanthrene than bentonite (62%) by the bacterium. The growth and proliferation of bacteria were supported by ABP which not only eliminated Cd toxicity through adsorption but also created a congenial microenvironment for bacterial survival. The macromolecules produced during ABP–bacteria interaction could form a stable clay-bacterial cluster by overcoming the electrostatic repulsion among individual components. Findings of this study provide new insights for designing clay modulated PAH bioremediation technologies in mixed-contaminated water and soil.

Detection of Mycobacterium Gilvum First Time from the Bathing Water of Leprosy Patient from Purulia, West Bengal

Introduction: Mycobacterium gilvum is a fast grower with smooth growth having pale yellow colour. This strain was first isolated from the sediment of the Grand Calumet River in North-western Indiana based on its ability to utilize pyrene, a toxic polycyclic hydrocarbon, as a growth substrate. Methods: The identification and characterization of this isolate was done by various conventional and molecular tests including 16S rDNA sequencing. Sequencing of the nearly complete 16S rRNA gene revealed a unique organism M.glivum, distantly related to M.vaccae group. Blast results showed similarity of these sequences with M.gilvum. Conclusion: Results might shed further light and its association with amoeba in the leprosy endemic area of this rare Mycobacterium species.

Effects of cytotoxicity of erythromycin on PAH-degrading strains and degrading efficiency

The MIC of erythromycin of pyrene degrading strain ofMycobacterium gilvumCP13.

Dual partitioning and attachment effects of rhamnolipid on pyrene biodegradation under bioavailability restrictions

We investigated the effects of different bioavailability scenarios on the rhamnolipid-enhanced biodegradation of pyrene by the representative polycyclic aromatic hydrocarbon degrader Mycobacterium gilvum VM552. This biosurfactant enhanced biodegradation when pyrene was provided in the form of solid crystals; no effect was observed when the same amount of the chemical was preloaded on polydimethylsiloxane (PDMS). An enhanced effect was observed when pyrene was sorbed into soil but not with the dissolved compound. Synchronous fluorescence spectrophotometry and liquid scintillation were used to determine the phase exchange of pyrene. We also investigated the phase distribution of bacteria. Our results suggest that the rhamnolipid can enhance the biodegradation of pyrene by micellar solubilization and increase diffusive uptake. These mechanisms increase substrate acquisition by bacterial cells at exposure concentrations well above the half-saturation constant for active uptake. The moderate solubilization of pyrene from PDMS by the rhamnolipid and the prevention of cell attachment may explain the lack of enhancement for pyrene-preloaded PDMS.

Development of eukaryotic zoospores within polycyclic aromatic hydrocarbon (PAH)-polluted environments: A set of behaviors that are relevant for bioremediation

In this study, we assessed the development (formation, taxis and settlement) of eukaryotic zoospores under different regimes of exposure to polycyclic aromatic hydrocarbons (PAHs), which imitated environmental scenarios of pollution and bioremediation. With this aim, we used an oomycete, Pythium aphanidermatum, as a source of zoospores and two PAH-degrading bacteria (Mycobacterium gilvum VM552 and Pseudomonas putida G7). The oomycete and both bacteria were not antagonistic, and zoospore formation was diminished only in the presence of the highest bacterial cell density (108–1010colony-formingunitsmL−1). A negative influence of PAHs on zoospore formation and taxis was observed when PAHs were exposed in combination with organic solutions and polar solvents. Co-exposure of PAHs with non-polar solvents [hexadecane (HD) and 2,2,4,4,6,8,8-heptamethylnonane (HMN)] did not affect zoospore settlement at the interfaces of the organic solvents and water. However, zoospores settled and created mycelial networks only at HD–water interfaces. Both bacteria diminished the toxic influence of PAHs on zoospore formation and taxis, and they did not interrupt zoospore settlement. The results suggest that zoospore development could be applicable for toxicity assessment of PAHs and enhancement of their bioavailability. Microbial interactions during both swimming modes and community formation at pollutant interfaces were revealed as major factors that have potential relevance to bioremediation.

Detection of Mycobacterium gilvum first time from the bathing water of leprosy patient from Purulia, West Bengal

In this present study for the first time the authors are reporting the isolation of Mycobacterium gilvum from the accumulated water in the drain connected to the bathing place of leprosy patients residing in an endemic region. The identification and characterization of this isolate was carried out by various conventional and molecular tests, including 16S rDNA sequencing. These findings might shed further light and association with amoeba in the leprosy endemic area of this rare Mycobacterium species.