Biology subjects

Kaushik, N.

Publications and source records attributed to Kaushik, N..

4 recordsLinked to original sources

bioRxiv2020

Screening of tomato seed bacterial endophytes for antifungal activity reveals lipopeptide producing Bacillus siamensis as a potential bio-control agent

The current study investigates the diversity pattern and fungicidal potential of bacterial endophytes isolated from two different organic varieties of tomato plants (V1 and V2). A total of seventy-four bacterial isolates identified by 16S rRNA sequencing revealed a single genus Bacillus with 16 different species. The Shannon diversity H (1.45), Simpsons index of diversity (0.9), Magalef index (2.1), Evenness (0.96), and Species richness (8) indicated the high endophytic bacterial diversity in the V1 variety of the tomato. Bacterial endophytes isolated from both the varieties were screened for their antifungal activity against five economically critical fungal pathogens (viz., Botrytis cinerea, Rhizoctonia solani, Fusarium solani, Verticillium lateritium, and Alternaria solani) of tomato crop through dual culture assay. The data revealed B. siamensis KCTC 13613(T) as the most potent antagonist significantly (p < 0.05), inhibiting the mycelial growth between 75 to 90% against selected fungal pathogens. High bioactivity of lipopeptide extract of B. siamensis was recorded against R. solani with IC50 value of 72 ppm. The UPLC-HDMS analysis of this lipopeptide extract revealed the presence of, Surfactin and Bacillomycin D.

microbiology↗

bioRxiv2020

HPLC analysis of Withania somnifera (Linn.) Dunal reveals two chemotypes in Indian germplasm and seasonal and genetic variability in Withaferin A -Content

HPLC methods for profiling and estimation of withanolide in Withania have been developed to study seasonal, geographical and genetic variation in Withaferin-A content and identify chemotypes. Highest withanolide content was observed during the vegetative phase and slight decrease was observed during reproductive phase. However, the content drastically reduced at the maturity. No significant effect of location was observed on the withanolide content when same genotypes were grown at two diverse locations. Withaferin-A content in Indian population of Withania somnifera varied from 0.22 to 3.38 % with a mean value of 1.099 in the leaves during vegetative stage.Whereas during maturity the content ranged from 0.0056 to 1.99 % with a mean value of 0.5942 %. In the roots, Withaferin-A content ranged from 0.0028 to 0.75 % with a mean value of 0.1242 during vegetative phase and 0.0008 to 0.1489 with a mean value of 0.00213 % at maturity of the plant. The population segregated into two chemotypes identified as chemotype-I and as an intermediate of Chemotype-I and Chemotype-II.

plant biology↗

bioRxiv2020

Combined effect of biological and physical stress on artificial production of agarwood oleoresin in Aquilaria malaccensis

Agarwood is the most expensive wood of the world and highly demanded wood in perfumery industry and ritual ceremonies of various religions. Agarwood is the infectious wood part of Aquilaria tree. Naturally, production of agarwood in Aquilaria takes 10-20 years of time and it can develop only in 1-2% of Aquilaria trees. Different types of biological, chemical and physical methods have been developed for artificial production of agarwood to fulfil the rising demand of the market. In the current article, we tried to explore combined effect of physical and biological stress in the form of stick method to improve agarwood production in Aquilaria malaccensis and compared it with well-known artificial fungal infection syringe method. Total 21 fungal strains were applied alone (syringe method) and with bamboo sticks (stick method). We found maximum infection occurred in stick method by fungi Penicillium polonicum AQGGR1.1 with 10 cm infection length. Artificial induction of marker compounds of agarwood, benzyl acetone and anisyl acetone were measured mostly in stick method, induced by 71.4% fungal strains grown on bamboo sticks, while alone only 42.9% fungi can induced in syringe method. Penicillium aethiopicum AQGGR1.2 found highly agarwood oleoresin inducing fungus in stick method and shown high potential agent in stick method for artificial production of agarwood.

microbiology↗

bioRxiv2018

A novel bioactive molecule 5-β-Hydroxyltridecanyl benzoate identified in Pedalium Murex L. (Gokhru) fruit extracts showed antifungal activity against Sclerotinia sclerotiorum

Fruits of Pedalium murex known as, Gokhru is predominantly used in Ayurveda for its aphrodisiac properties and use in treatment of urological orders. However till now, bioactivity of this fruit has not been documented for plant protection against phytopathogenes, Hence in this regard, we investigated antimicrobial activity of P. murex fruit extracts (isolated from the different agro climatic zones of India) were tested against twelve microbial phytopathogens. From 29 fruit extracts, only 13 were found to be active against three pathogens viz. Botrytis cinerea, Rhizoctonia solani, and Sclerotinia sclerotiorum. Among the nine TLC fractions only one showed presence of a single peak, thus presence of a single compound in the crude extract. Based on lower IC50 value (328 g/ml) the crude fruit extract collected from Indore region was further characterized. Evaluation against screened phytopathogens indicates its activity. Further, structural characterization of this compound using FTIR and NMR revealed it to be a novel compound i.e. 5-{beta}-Hydroxyl tridecanyl benzoate. Our study paves a way to investigate effective dose of P. murex fruit extracts to utilize in plant protection programs. In future, a better method is required to scale up the process of bioactive molecule (5-{beta}-Hydroxyl tridecayl benzoate) extraction from P. murex or for its chemical synthesis.

microbiology↗