Twenty nine isolates of bacterial strains were isolated from 12 different composts, namely vermicompost, NADEP compost, Cow Pat Pit manure (CPP), biodynamic compost, cow horn manure (BD 500), panchakavya, biodynamic herbal preparations, such as BD 502, BD 503, BD 504, BD 505, BD 506 and BD 507. The water extract from organic manures had antibacterial properties and production of subtilin (1.083 OD at 254 nm). Among the organic manures tested for subtilin, the CPP manure contained highest amount of subtilin (0.967 OD at 254 nm). Among the 12 manures analyzed for the enumeration of microorganisms, CPP manure contained the highest amount of bacterial load (4.8 cfu x 10⁶ per gram of manure) and the beneficial bacteria such as Rhizobium like colonies (1.9 cfu x 10⁶), Azospirillum sp. (0.2 cfu x l0⁶), Azotobacter (0.8 cfu x 10⁶) were recorded. Among bacterial strains isolated from different composts, Bacillus subtilis was predominant in the CPP manure. Bacillus subtilis produced subtilin (0.216 OD at 254 nm) and suppressed the growth of different bacterial pathogens such as Staphylococcus aureus, Escherichia coli, Micrococcus lutes and Erwinia amylovora. The growth of Bacillus subtilis and production of subtilin on CPP manure were analyzed periodically for a period of 90 days. The maximum growth (4.8 x 10⁶/g of manure) and subtilin production (1.078 OD at 520 nm) by bacterium were observed on 90 days and 75 days respectively. After 90 days of CPP maturation, a decrease in subtilin and protein content were observed.

Bacterial and fungal diseases on crops are one of the major factors limiting crop production. In many countries, biocontrol agents are used in agriculture and horticulture or even in food storage. Bacillus subtilis, Pseudomonas fluorescence, P. resinovorans, P. malculicola, Agrobacterium radiobacter, Streptomyces lydicus, Burkholderia solanacearum and Burkholderia cepacia are the important bacterial biocontrol agents having number of industrial applications. Bacillus subtilis has the ability to produce a range of antibiotic compounds that are inhibitory to pathogenic fungi, bacteria and insects (Collins and Jacobsen, 2003). Several fungal biocontrol agents, such as Chaetomium sp., Coniothyrium sp., Cladosporium sp., Gliocladium sp. and Trichoderma sp., were extensively deployed in sustainable agriculture practices (Hoitink, 1980). The soil amendments of selected organic materials suppress soil-borne plant pathogens (Hoitink and Fahy, 1986; Hoitink and kuter, 1986; Epstein, 1997; Hoitink and Boehm, 1999). Hirether to limited information is available on antifungal and antibacterial properties of organic and biodynamic manures. Hence the present investigation aimed to screen the organic manures for antibacterial properties, identify the predominant bacterium and to use organic manure as natural medium for maximum production of antibiotics.

Different organic manures, such as vermicompost, NADEP compost, CPP, biodynamic compost, cow horn manure (BD 500), panchakavya, biodynamic herbal preparations, such as BD 502, BD 503, BD 504, BD 505, BD 506 and BD 507 were obtained from Shri AMM Murugappa Chettiar Research Centre, Taramani, Chennai and Kurinji Organic Foods Pvt. Ltd., Genguvarpatti, Tamil Nadu.