DIVERSITY OF MARINE ACTINOMYECTES IN THE RHIZOSPHERE OF COASTAL SAND DUNES AND THEIR BIOTECHNOLOGICAL APPLICATIONS

Abstract

In this work, an exhaustive collection of newline300 marine actinomycetes were isolated from the coastal sand dune newlinerhizosphere soil, which is a neglected ecosystem so far. Out of the 300 newlineactinomycetes 70 morphologically distinct salt tolerant actinomycetes were newlineselected to analyse their beneficial bioactivities such as antagonistic newlineproperties, production of secondary metabolites and biological control of newlinefusarial wilt in tomato plant under screen house conditions. The study has newlinerevealed that the salt tolerance of the actinomycetes from the coastal sand newlinedune rhizosphere soil was up to 12%. These actinomycetes which have newlinetolerance to high salinity levels were able to produce lytic enzymes such as newlineamylase, caseinase, chitinase, gelatinase, pectinase and tannase. The newlineactinomycetes were able to inhibit potential phytopathogens such as newlineRhizoconia solani, Sclerotium rolfsii and Fusarium oxysporum in dual plate newlineassay and disc diffusion assay. 57% of the actinomycetes were able to inhibit newlinethe selected phytopathogens. A total of 50 selected marine actinomycetes newlinewere subjected to in vitro plant growth promotion studies. Qualitative assay newlineto detect the production of IAA was done with the culture filtrates of the 50 newlineselected actinomycetes. The actinomycetes had also shown growth newlinepromotion in four crop plant seeds such as rice, wheat, green gram and black newlinegram. Of all the 50 strains, AMET030, AMET047, AMET053, AMET056, newlineAMET065, AMET066 and AMET069 have generally showed maximum newlinegermination percentage in all the seeds. newline