International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438 Volume 4 Issue 2, February 2015 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Isolation of Antagonistic Actinomycetes SPS from Rhizosphere of BT Cotton T. Sujatha 1 , P. Siva Raagini 2 1 & 2 Department of Applied Microbiology, Sri Padmavati Mahila Visvavidyalayam, Tirupati. A.P. India. 1 SR&BGNR Government Arts and Science College, Khammam.Telangana state, India . Abstract: The plant microbe interaction in the rhizosphere is one of the major factors regulating the health and growth of plants. Actinomycetes are common filamentous soil microorganisms important in maintaining a satisfactory biological balance in the soil, largely because of the ability to produce antibiotics. In the present study Antagonistic Actinomycetes species was isolated from rhizosphere of Bt cotton. Seven types of isolated Actinomycetes colonies were isolated from crowded plate method and were screened primarily by Giant colony technique. Three strains with best antifungal activity were further screened by Well Diffusion method and the best member which has good antifungal activity was selected and named as BtAS. This strain was studied for it’s morphological, physiological characteristics according to Bergey’s Manual and further studied by molecular characterization and was identified as Streptomyces filamentosus. The 16s rRNA gene sequence (1472 bp) of isolate was deposited at NCBI GeneBank with Accession Number KF939135. The antagonistic nature of the isolated strain was determined for its anti-fungal activity by Well Diffusion method, MIC and Inhibition of phytopathogenic fungi likeA. alternata,F.moniliformae, M. phaseolina, R. solaniand A. niger in liquid medium. The results indicate that Streptomyces filamentosusisolatedfrom rhizosphere of Bt cotton has Good Antifungal activity and it was more effective against F.moniliformae when compared with other test fungi. Keywords: Rhizosphere,Antagonistic,Crowded plate, Giant colony technique,Well Diffusion method, phytopathogenic,MIC 1. Introduction Cotton (Gossypium herbacium arboreu) was the one of the important commercial crop in India. Among the total cultivation of the Cotton crop, Bt cotton occupies 90 % of it. Bt-cotton incorporated with Cry1Ac is highly toxic to the bollworms (Helicoverpa armigera) and other minor pests such as the cotton semilooper (Spodoptera litura) and hairy caterpillar [1].The Rhizosphere contains a large and majority of the soil biota. The plant microbe interaction in the rhizosphere is one of the major factors regulating the health and growth of plants. Soil bacteria living in the rhizosphere can enhance plant growth by several mechanisms like antagonism against plant pathogens, solubilization of phosphates [2], production of phytohormones [3], siderophores production [4], antibiotic production [5], inhibition of plant ethylene synthesis [6] and induction of plant systemic resistance to pathogens [7]. The study of rhizosphere is important as far as control of soil pathogens which pass through the rhizosphere and infect root system. Biological control is a common phenomenon in a soil ecosystem. It is a site for complex diverse microbe mediated processes. Several microorganisms like Actinomycetes secrete low levels of antibiotic compounds as their secondary metabolites. Many of them are effective against bacteria, fungi and actinomycetes which maintain natural soil health. This is a continuous process which can inhibit or kill some of the plant pathogens in that vicinity. Actinomycetes are common filamentous soil microorganisms important in maintaining a satisfactory biological balance in the soil, largely because of the ability to produce antibiotics. They are also known to be actively involved in degradation of complex organic materials in soils and contribute to the biogeochemical transformations. Most of the actinomycetes are capable of producing wide variety of cell wall degrading enzymes like chitinases, glucanases, cellulases, hemicellulases, amylases etc. These are also known to produce several antifungal compounds that are being exploited commercially for the control of several microbial plant diseases. 2. Materials and Methods 2.1 Soil Sampling The study area covers Khammam district, Telangana State, India. Three villages namely Ammapalem, V.V.palem and Thallada of Konejerla mandal, were selected for field study. The selected sites are being used to cultivate Bt cotton continuously for more than ten years consecutively without an alternate crop. Rhizospheric soils were collected from 60 days crop of Bt Cotton. Rhizospheric soil samples were taken from five fields from each village. Five transects across each plot were chosen. The soil samples were collected at different points (five points) from each transects to get 125 soil samples from one village. Like this from all the three villages separate 125 Bt cotton rhizospheric soils were collected. ONE VILLAGE FIVE FIELDSFIVE TRANSECTS FROM EACH FIELD FIVE POINTS FROM EACH TRANSECT (5X5X5=125). All the 125 samples from each village were mixed to get one representative soil sample. After removal of plant debris, the samples were sieved using 2mm mesh size sieve and air dried. Then they were labeled and transported to the laboratory in polyethylene bags and stored at 4 0 C, and were further used for the isolation of antagonistic Actinomycetes. Paper ID: SUB151517 1373