Biology subjects

Barooah, M.

Publications and source records attributed to Barooah, M..

4 recordsLinked to original sources

bioRxiv2019

Mechanism of interaction of an endofungal bacterium Serratia marcescens D1 with its host and non-host fungi

Association of bacteria with fungi is a major area of research in infection biology, however, very few strains of bacteria have been reported that can invade and reside within fungal hyphae. Here, we report the characterization of an endofungal bacterium Serratia marcescens D1 from Mucor irregularis SS7 hyphae. Upon re-inoculation, colonization of the endobacterium S. marcescens D1 in the hyphae of Mucor irregularis SS7 was demonstrated using stereo microscopy. However, S. marcescens D1 failed to invade into the hyphae of the tested Ascomycetes (except Fusarium oxysporum) and Basidiomycetes. Remarkably, Serratia marcescens D1 could invade and spread over the culture of F. oxysporum that resulted in mycelial death. Prodigiosin, the red pigment produced by the Serratia marcescens D1, helps the bacterium to invade fungal hyphae as revealed by the increasing permeability in fungal cell membrane. On the other hand, genes encoding the type VI secretion system (T6SS) assembly protein TssJ and an outer membrane associated murein lipoprotein also showed significant up-regulation during the interaction process, suggesting the involvement of T6SS in the invasion process.

microbiology↗

bioRxiv2019

Endophytic Virome

Endophytic microorganisms are well established for their mutualistic relationship and plant growth promotion through production of different metabolites. Bacteria and fungi are the major group of endophytes which were extensively studied. Virus are badly named for centuries and their symbiotic relationship was vague. Recent development of omics tools especially next generation sequencing has provided a new perspective towards the mutualistic viral relationship. Endogenous virus which has been much studied in animal and are less understood in plants. In this study, we described the endophytic viral population of tea plant root. Viral population (9%) were significantly less while compared to bacterial population (90%). Viral population of tea endophytes were mostly dominated by endogenous pararetroviral sequences (EPRV) derived from Caulimoviridae and Geminiviridae. Subclassification of Caulimoviridae showed the dominance of Badnavirus (42%), Caulimovirus (29%), Soymovirus (3%), Tungrovirus (3%), while Geminviridae was only represented by genus Bagmovirus. Interestingly, the endophytic virome sequence from root also showed the presence of phage virus from order Caudovirales. Identified sequence from Caudovirales were Myoviridae and Siphoviridae. Sequence comparison with viral population of soil and root showed the possibility of horizontal transfer of Caudovirales from soil to root environment. This study will expand the knowledge on endogenous viruses especially for tea plant. This study will also help us to understand the symbiotic integration of viral particle with plant which could be used in broader sense to tackle different agronomic problems.\n\nSignificance StatementVirus were badly named for centuries and mostly known for their disease-causing abilities. But recent development of omics tools has focused another facet which is symbiotic. This paper discusses about viral community identified from shotgun sequence of tea root samples which are endogenous in origin. Interestingly, we also identified sequences of phage virus from Caudovirales family which possibly have transmitted from soil. Here we also compared the soil virome community with tea virome to establish the hypothesis. This research will broaden the current knowledge on symbiotic relationship of virus and plant.

microbiology↗

bioRxiv2018

Diversity of Culturable Endophytic bacteria from Wild and Cultivated Rice showed potential Plant Growth Promoting activities

In this paper, we report the endophytic microbial diversity of cultivated and wild Oryza sativa plants including their functional traits related to multiple traits that promote plant growth and development. Around 255 bacteria were isolated out of which 70 isolates were selected for further studies based on their morphological differences. The isolates were characterized both at biochemical and at the molecular level by 16s rRNA gene sequencing. Based on 16S rRNA gene sequencing the isolates were categorized into three major phyla, viz, Firmicutes (57.1 %), Actinobacteria (20.0 %) and Proteobacteria (22.8 %). Firmicutes was the dominant group of bacteria of which the most abundant genus was Bacillus. The isolates were further screened in vitro for plant growth promoting activities which revealed a hitherto unreported endophytic bacterial isolate, Microbacteriaceae bacterium RS01 11 as the highest secretor of a phytohormone, IAA (28.39 {+/-} 1.39 g/ml) and GA (67.23 {+/-} 1.83 g/ml). Bacillus subtilis RHS 01 displayed highest phosphate solubilizing activity (81.70 {+/-} 1.98 g/ml) while, Microbacterium testaceum MK LS01, and Microbacterium trichothecenolyticum MI03 L05 exhibited highest potassium solubilizing activity (53.42{+/-}0.75g/ml) and zinc solubilizing efficiency (157.50%) respectively. Bacillus barbaricus LP20 05 produced highest siderophore units (64.8 %). Potential plant growth promoting isolated were tested in vivo in pot culture under greenhouse conditions. A consortium consisting of Microbacteriaceae bacterium RS01 11, Bacillus testaceum MK LS01 and Bacillus subtilis RHS promoted plant growth and increased the yield 3.4 fold in rice when compared to control T0 when tested in pot culture and reduce application rates of chemical fertilizer to half the recommended dose. Our study confirms the potentiality of the rice endophytes isolated as good plant growth promoter and effective biofertilizer.

microbiology↗

bioRxiv2017

Identification and characterization of siderophore producing arsenic tolerant Staphylococcus sp. TA6 and its possible involvement in arsenic geocycle

The presence of arsenic in sediments, carbonaceous rocks are geogenic, while its entry into the aquifers is mediated by several factors including microorganisms. It is well known that the microorganisms play a crucial role in the biogeochemical cycle of different elements. However, the precise role of bacteria in regulating the concentration of arsenic in Brahmaputra valley has not been investigated in detail. In this paper, we report the isolation of arsenic resistant bacterium TA6 with active arsenate reduction efficiency. The isolate was able to grow in arsenate concentration (250 mM) and arsenite (30 mM). Along with resistance to inorganic arsenic, it showed cross-tolerance to other heavy metals like Hg+2, Cd+2, Co+2, Ni+2, Cr+2. The bacterium also had a high siderophore activity (78.7 {+/-} 0.004 mol), which is positively correlated with the resistance aptitude. The biochemical test showed the TA6, a gram-positive bacterium which can hydrolyze starch and casein, produce catalase enzyme and utilizes citrate as a metabolic trait. Molecular and chemotaxonomic identification of TA6 based on 16S rRNA and FMAE analysis showed similarity with members of Staphylococcus genus with significant difference in sequence similarity and fatty acid composition. Based on 16S rRNA and FAME analysis it was identified as Staphylococcus sp. TA6. Rate of biotransformation showed bacterium could reduce ~88.2% of initial 2mM As(V) into As(III). The characterization of arsenate reductase enzyme with NADPH coupled assay showed the highest activity at pH 5.5 and temperature 50{degrees}C.

microbiology↗