Chaudhari, D. | Search bioRxiv

bioRxiv2019

Description of Klebsiella indica sp. nov., isolated from the surface of tomato.

A novel bacterial strain designated TOUT106T was isolated from the surface of a tomato collected from the local vegetable market in Pune, India. The cells were rod shaped, Gram-stain-negative, encapsulated and non-motile. The strain TOUT106T grows as mucoid and translucent colonies on blood agar medium and the best growth was observed at 28{degrees}C and at pH 7.0, and could tolerate up to 2% (w/v) NaCl. On the basis of 16S rRNA gene sequence analysis, strain TOUT106T was placed under Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42%). Genome-based phylogenetic analysis revealed that the strain forms a distinct branch within the Klebsiella clade and K. michiganensis DSM25444T and K. oxytoca NBRC105695T were the closest neighbor. The genomic DNA G+C content of strain TOUT106T was 53.53 mol%. The average nucleotide identity of TOUT106T was less 86.4% with closely related members of the family Enterobacteriaceae. The major fatty acids of strain TOUT106T were C16:0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14:0, C19:0 cyclo w8c, C18:1 w6c/C18:1 w7c, C12:0 and C16:1 w7c/C16:1 w6c. The strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS to its closest relatives. Based on the phenotypic including chemotaxonomic properties and phylogenetic analysis the strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella, was suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T).

microbiology↗

bioRxiv2019

Homogenization of Rhizosphere Bacterial Communities by Pea (Pisum sativum L.) Cultivated under Different Conservation Agricultural Practices in the Eastern Himalayas

Conservation agriculture offers a suitable system to harmonize agriculture with the environment, especially in fragile ecosystems of North-East India. Soil microbes play pivotal roles in ecosystem functioning and act as indispensable indicators of overall fitness of crop plant and soil health. Here we demonstrated that altercations in residue management and tillage practices lead to the development of differential bacterial communities forcing the pea plants to recruit special groups of bacteria leading to highly homogenous rhizosphere communities. Pea rhizosphere and bulk soil samples were collected, and bacterial community structure was estimated by 16S rRNA gene amplicon sequencing and predictive functional analysis was performed using Tax4Fun. The effect on pea plants was evident in the bacterial communities as the overall diversity of rhizosphere samples was significantly higher to that of bulk soil samples. Bacillus, Staphylococcus, Planomicrobium, Enterobacter, Arthrobacter, Nitrobacter, Geobacter, and Sphingomonas were noticed as the most abundant genera in the rhizosphere and bulk soil samples. The abundance of Firmicutes and Proteobacteria altered significantly in the rhizosphere and bulk samples, which was further validated by qPCR. Selection of specific taxa by pea plant was indicated by the higher values of mean proportion of Rhizobium, Pseudomonas, Pantoea, Nitrobacter, Enterobacter and Sphingomonas in rhizosphere samples, and Massilia, Paenibacillus and Planomicrobium in bulk soil samples. Tillage and residue management treatments did not significantly alter the bacterial diversity, while their influence was observed on the abundance of few genera. Recorded results revealed that pea plant selects specific taxa into its rhizosphere plausibly to meet its requirements for nutrient uptake and stress amelioration under the different tillage and residue management practices.

microbiology↗