Original Research Article DOI: 10.18231/2394-5478.2018.0040 Indian Journal of Microbiology Research, April-June, 2018;5(2):188-193 188 Purification and characterization of bioactive secondary metabolites isolated from soil bacteria Amit Pandey 1 , Ankita Srivastava 2 , Niharika Chandra 3 , Dheerendra Kumar 4 , Sunil Kumar 5,* 1,2,4 Research Scholar, 3 Assistant Professor, 5 Associate Professor, Faculty of Biotechnology, Institute of Bio-Sciences and Technology, Shri Ramswaroop Memorial University, Barabanki, Uttar Pradesh, India *Corresponding Author: Email: sunil.bio@srmu.ac.in Abstract The search for new bioactive compounds from the natural environment has rapidly been gaining momentum with the increase in multi-drug resistant (MDR) pathogens. In the present study, the antimicrobial potential of new bacterial species has been evaluated by initial screening of fourteen soil samples. Primary and secondary screening was performed against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Four active isolates were selected for further study. Microbial strains were identified on the basis of growth conditions and other biochemical characters. One most active microbial strain was identified using 16S rRNA sequence homology and designated as Bacillus cereus (C13). Furthermore the production of secondary metabolites was done in optimized production media and the analysis involved HPLC method to identify metabolites based on retention time where 2.833 min retention time obtained using C18 column at 265 nm wavelength, which is similar to valinomycin antibiotic which is also secreted by Streptomyces griseus. It shows presence of bioactive secondary metabolites which is responsible for antibacterial activity of bacterial isolates. Keywords: Antimicrobial activity, Actinomycetes, Methanolic extract, Minimum inhibitory concentration, Streptomyces. Introduction The production of secondary metabolites from actinobacteria has been the most economical and biotechnological source for the discovery of new antibiotics. It has already been lead to some important antimicrobial drugs like vancomycin, chloramphenicol and tetracycline. The development of new naturally occurring antimicrobial agents with novel mechanisms of action is an urgent medical need. Soil is an extensively exploited ecological niche; the inhabitants of soil produce several useful bioactive natural products, including clinically important antibiotics. However, the emergence of drug and multidrug- resistant pathogens 1 necessitates a continuing search for new antimicrobial compounds with potent antimicrobial activity. Searching for previously unknown microbial strains is an effective approach for obtaining new bioactive substances. Therefore, it is indeed need of the hour to search for new drugs, especially antibiotics, to control the spread of antibiotic resistant pathogens. 2-4 It is well proven that microbial metabolites are rich sources for new potential therapeutic drugs. 5,6 Hundreds or thousands of antibiotics have been identified from the cultures of bacteria and fungi, but only about 100 antibiotics alone have been used to treat human and animal diseases. 7 The search for less toxic, more potent antibiotics from non-infective organisms, which overcome the resistance exhibited against the existing antibiotics, is most required at present. In the past, many important bioactive compounds of high commercial value have been reported to be obtained from actinomycetes. Therefore, actinomycetes are continuing to be routinely screened for new bioactive substances. As per the past reports approximately two- thirds of naturally occurring antibiotics have been isolated from actinomycetes. 8,9 A wide variety of secondary metabolites can be produced from Actinomycetes, which are prolific producers of antibiotics and important suppliers to the pharmaceutical industry. 10 Actinomycetes are naturally useful in the pharmaceutical industry for their apparently unrestricted capacity to produce secondary metabolites with varied chemical structures and biological activities. 11 Though thousands of antibiotics have been isolated from Streptomyces, even it represents only a small fraction of the repertoire of bioactive compounds produced. 12-14 Therefore, isolation of new Streptomyces from natural resources and characterization of their secondary metabolites is a valuable effort. Streptomyces species are Gram- positive, aerobic microorganisms and produce about half of all known antibiotics from microorganisms. 15 Streptomyces species constitutes 50% of the total population of soil actinomycetes and 75-80% of the commercially and medicinally useful antibiotics. 16 The aim of the present study was to isolate antimicrobial metabolite producing bacteria from soil samples collected from different locations of Lucknow and nearby area, Uttar Pradesh, India which an ecologically reach region. This area is poorly studied and represents the diverse and largely unscreened ecosystem. The aim of the present study was to isolate antimicrobial metabolite producing bacteria from soil samples collected from different locations of Lucknow and nearby area, Uttar Pradesh, India which is an ecologically reach region. This area is poorly studied and represents the diverse and largely unscreened ecosystem.