Research Journal of Recent Sciences _________________________________________________ ISSN 2277-2502 Vol. 1(11), 22-26, November (2012) Res.J.Recent Sci. International Science Congress Association 22 Antimicrobial Activity of Phospholipid Compound Produced by Acidophilic Bacillus subtilis Isolated from Lonar Lake, Buldhana, India More S.M. 1 , Shinde V.A. 1* , Khan Saiqua 1 , Girde A.V. 1 and Pawar V.N. 2 1* Department of Microbiology, Yeshwant Mahavidyalaya, Nanded- 431602, MS, INDIA 2 Department of Food Science and Technology, College of Agricultural Technology, M.A.U. Parbhani, MS, INDIA Available online at: www.isca.in Received 9 th August 2012, revised 25 th October 2012, accepted 30 th October 2012 Abstract Bacillus subtilis is an endospore forming rhizobacteria; produces several antibiotics with amazing structural variety viz. subtilosin, bacitracin, difficidin, fengycin, mersacidin, bacilysocin and iturin. These antimicrobial compounds are effective against both gram positive and gram negative bacteria. Bacillus subtilis has ability to grow in extreme environments like alkaliphilic, acidophilic, acidophilic. These environmental conditions induce microorganisms to produce varied kinds of antimicrobials which have applications in chemotherapy. Therefore in the present study Acidophilic Bacillus subtilis (B. subtilis) strains were isolated from soil samples of Lonar lake and screened for production of phospholipid antibiotic. The purified phospholipid antibiotic showed broad spectrum activity against the test organisms i.e. Escherichia coli (E. coli), Staphalococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Candida parapsilosis (C. parapsilosis); of these test organisms staphylococcus aureus showed higher sensitivity towards the phospholipids antimicrobial compound. Keywords: Bacillus subtilis, acidophilic, phospholipid, bioactive compound. Introduction Soda lakes are the most stable and productive naturally occurring alkaline environments in the world, with pH values generally higher than 10 and occasionally reaching 12 1 . These alkaline environments are caused by a combination of geological, geographical and climatic conditions. They are characterized by large amounts of sodium carbonate formed by evaporative concentration 2 . The microbes present in such alkaline saline environments play an important role in the remineralization of organic matter within the ecosystem. They are the major contributors in the transformation of organic carbon, sulfur, nitrogenous compounds and metals with an important role in food webs and nutrient cycling. The ecology and diversity of an East African Soda Lake was studied and extensively reviewed for their biotechnological potential 3 . The microbial diversity of saline lakes has been studied primarily by focusing on the isolation and characterization of individual organisms with potential industrial application 4,1 . However, there is meager data on the bacterial diversity of Lonar lake. Eutrophication and presence of blue green algae in Lonar lake have been described 5 . Some workers 6 have studied the alkaline metalloprotease from alkaline Streptomyces isolated from Lonar lake silt sample. Bioremediation of phenol-using alkaliphilic bacteria isolated from Lonar lake sediments was an interesting finding 7 . A preliminary account of bacterial diversity of the Lonar Lake ecosystem has been reported 8 , which includes some of the biochemically identified isolates. Applied culture dependent phenotypic characterization and 16S rDNA-based phylogenetic analyses were applied to study aerobic, cultivable bacterial populations present in the alkaline Lonar Lake. The isolates were further studied for their biotechnological potential 7 . The spread of resistance to antibiotics undermines the therapeutic utility of anti-infective drugs in current clinical use 9 . For example, Staphylococcus aureus, a major cause of community and hospital acquired infections, has developed resistance to most classes of antibiotics, and isolates exhibiting such resistance is drawing great concern. Methicillin-resistant S. aureus (MRSA) strains appeared in the hospital environment after introduction of the semi synthetic Penicillin, Methicillin leaving Vancomycin as the last line of defense for MRSA treatment 10 . With the appearance of vancomycin-resistant clinical isolates 11 , no antibiotic class is effective against multiresistant S. aureus infections. Thus, new antibiotic and therapy options are urgently needed to improve the management of bacterial infections 12 , and a major challenge is to find drugs that act against Methicillin-resistant S. aureus (MRSA). The gram positive bacterium Bacillus subtilis produces a large number of antibiotics, which are classified as ribosomal or non- ribosomal. The non-ribosomal antibiotics may play a role in competition with other microorganisms during spore germination 13 . The high proportion of antimicrobial compounds producing strains may be associated with ecological role, playing a defensive action to strains into an established microbial community 14 . It has been very recently shown that the biosynthesis of difficidin and bacillaene in B. subtilis A1/3 is dependent on a Sfp-homologous PPan transferase 15 . A series of new antibiotics have been recently isolated from well-known B. subtilis strains. These include bacilysocin, an anti-microbial