Molecular characterization of an endophytic Phomopsisliquidambaris CBR-15 from Cryptolepis buchanani Roem. and impact of culture media on biosynthesis of antimicrobial metabolites.

An endophytic fungus Phomopsis liquidambaris CBR-15, was isolated from Cryptolepis buchanani Roem. (Asclepiadaceae) and identified by its characteristic culture morphology and molecular analysis of the ITS region of rDNA and intervening 5.8S rRNA gene. The impact of different culture media on biosynthesis of antimicrobial metabolites was tested by disc diffusion assay. Polyketide synthase gene (PKS) of the endophytic fungus was investigated using three pairs of degenerate primers LC1-LC2c, LC3-LC5c and KS3-KS4c by PCR. TLC-bioautography method was employed to detect the antimicrobial metabolites. Antimicrobial metabolites fractionated with ethyl acetate extract showed significant antimicrobial activity against the test bacteria and fungi. Biosynthesis of antimicrobial metabolites was optimum as depicted by zone of inhibition from ethyl acetate extract cultured in potato dextrose broth. Strain CBR-15 was identified as Phomopsisliquidambaris and PKS genes of the fungus were amplified with LC3-LC5c and KS3-KS4c sets of degenerate primers. These findings suggest that endophytic P.liquidambaris CBR-15 harbor iterative type I fungal PKS gene domain which indicates the biosynthetic potential of endophytic fungi as producers of natural antimicrobial metabolites. The study also demonstrates the utilization and optimization of different culture media which best supports for the biosynthesis of the antimicrobial metabolites from P.liquidambaris.

Molecular identification and characterization of Fusarium spp. associated with sorghum seeds.

BACKGROUND: Fusarium spp. are not only pathogenic to plants but are also known as toxin producers that negatively affect animal and human health. The identification of Fusarium spp. remains one of the most critical issues in fungal taxonomy. In this study, different strains of Fusarium spp. were isolated from sorghum seed samples and identified at the molecular level by tef-1α gene amplification. A multiplex polymerase chain reaction (mPCR) assay was developed to differentiate toxigenic and non-toxigenic Fusarium spp. by designing a primer for the Fum21 gene along with the Fum1 and Fum8 genes. A competitive direct enzyme-linked immunosorbent assay (CD-ELISA) was employed to assess the fumonisin-producing ability of Fusarium spp. Phylogenetic analyses were performed using partial sequences of tef-1α and inter-simple sequence repeat (ISSR) markers of different Fusarium spp. RESULTS: All 27 isolates of Fusarium spp. were positive for the tef-1α gene and revealed the presence of F. verticillioides, F. thapsina and F. cf. incarnatum-equiseti complex. The standardized mPCR assay distinguished toxigenic and non-toxigenic F. verticillioides. Further, mPCR fumonisin-positive F. verticillioides isolates were also positive by CD-ELISA. The tef-1α gene sequence was found to be useful in revealing intraspecific polymorphism to some extent. ISSR markers revealed a high level of polymorphism among different isolates of Fusarium spp., and the dendrogram of ISSR analyses grouped the 27 isolates into two major clusters. CONCLUSION: The present method provided rapid and reliable detection of fumonisin-producing Fusarium spp. The mPCR assay could be an alternative strategy to current conventional mycotoxin analytical techniques and a reliable tool for high-throughput monitoring of major mycotoxin-producing fungi during the processing steps of food and feed commodities.

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Plant mediated nanoparticles' synthesis has led to a remarkable progress via unfolding a green synthesis protocol towards nanoparticles' synthesis. It seems to have drawn quite an unequivocal attention with a view of reformulating the novel strategies as alternatives for popular conventional methods. Hence, the present review summarizes the literature reported thus far and envisions towards plants as emerging sources of nanofactories.