Srividya S, Adarshana Thapa, Deepika V Bhat, Kajingailu Golmei and Nilanjan Dey
The study identified a potent Actinomycete isolate 9p with broad spectrum antifungal property against four phytopathogens tested- Alternaria brassiceae OCA3; Collectotrichum gleosporioides OGC1; Rhizoctonia solani MTCC 4633 and Phytophthora capsici. The isolate was identified as Streptomyces sp. based on colony morphology, microscopy and 16srDNA. The isolate produced 2 most important hydrolytic enzymes- chitinase and β-1, 3 glucanase along with cellulase, lipase and protease. The strain 9p produced relatively high levels of chitinase (696 U/mL) at day 4 of the incubation period. Meanwhile, the highest level of β -1,3-glucanase (392 U/mL) was also found at day 4 of the incubation period and subsequently decreased slightly during the stationary phase. Among the various carbon sources tested in the ISP media, all carbon amendments supported induction of both chitinase and glucanase. Even the autoclaved mycelia of Colletotrichum gleosporoides (OGC1) and Alternaria brassicae (OCA3) supported appreciable levels of both the enzymes. Concurrent production of protease, lipases, siderophore, IAA production coupled with anti-fungal activity suggests the plant growth promotion and broad spectrum biocontrol potential of this isolate. The strain 9p exhibited mixed path antagonism type of mechanisms of biocontrol through the production of mycolytic enzymes. Isolate showed 87.5% germination index when coated onto chilli seeds. This coupled with antifungal properties, suggests both the PGPR and biocontrol aspect of the actinomycete Streptomyces sp. 9p.
