S1147 Document heading Isolation and partial characterization of actinomycetes with antimicrobial activity against multidrug resistant bacteria Smriti Singh 1 , Pramod Kumar 2 , N Gopalan 2 , Bhuvnesh Shrivastava 3 , RC Kuhad 3 , Hotam Singh Chaudhary 1* 1 Department of Biotechnology, Madhav Institute of Technology & Science, Gwalior-474005, India 2 Defense Research and Development Establishment, Gwalior-474002, India 3 Lignocellulose Biotechnology Laboratory, Department of Microbiology, University of Delhi, N Delhi, India Asian Pacific Journal of Tropical Biomedicine (2012)S1147-S1150 Asian Pacific Journal of Tropical Biomedicine journal homepage:www.elsevier.com/locate/apjtb *Corresponding author: Hotam Singh Chaudhary, Assistant Professor, Department of Biotechnology, Madhav Institute of Technology & Science, Gwalior - 474005, India. Tel: (0751) 2409352 E-mail: hotamsingh@gmail.com 1. Introduction Actinobacteria, high guanine and cytosine (曒55 %) containing bacteria is one of the dominant phyla of the bacteria found on almost natural substrates [1,2] . They play an important role in decomposition of organic materials and carbon cycle. T he taxonomy of the actinomycetes has been subject to unending controversy because of its filamentous, branching growth which resembles with a fungal type of morphology [3] . Actinomycetes represent a high proportion of the soil microbial biomass and have the capacity to produce a wide variety of antibiotics and extracellular enzymes [4,5] . Most of the known natural antibiotics are produced from actinomycetes [5] . Moreover, these are important source for novel antibiotics and hence having a high pharmacological and commercial interest including control of infectious diseases [6-8] . Medical or economic significant Actinobacteria mainly lies in subclass Actinobacteridae, order Actinomycetales. The order Actinomycetales is composed of approximately 80 genera, nearly all from terrestrial soils, where they live primarily as saprophytes. Actinomycetes are important sources of new bioactive compounds such as antibiotics and enzymes [6,9,10] which have diverse clinical effects and are active against many pathogenic organisms Actinomycetes and their bioactive compound show antibacterial and anti microbial against various pathogens and multi drug resistant pathogens e.g. Vancomycin-Resistant Enterococci , Methicillin- R esistant Staphylococcus aureus ( S. aureus) , Shigella dysenteriae ( S. dystranae) , Klebsiella sp. and Pseudomonas aeruginosa ( P. aeruginosa ) etc [11-14] . T he need for new, safe and effective antimicrobial agent is the major challenge to the pharmaceutical industry now a days, especially with the obvious increase in opportunistic infections in the immune compromised host via and multiple drug resistant strains [10] . A mong all the known microbes, members of the actinomycetes genus especially Streptomyces species have been recognized as prolific producer of useful ARTICLE INFO ABSTRACT Article history: Received 8 June 2012 Received in revised from 5 July 2012 Accepted 7 August 2012 Available online 28 August 2012 Keywords: Actinomycetes Methicillin-Resistant Staphylococcus aureus Vancomycin-Resistant Enterococci (VRE). Objective: To isolate strains of Actinomycetes from different locations of Gwalior to evaluate its antimicrobial activity against multidrug resistant pathogenic strains. Method: Soil samples collected from different niche habitats of Gwalior were serially diluted and plated on selective media. Potential colonies were further purified and stored in agar slants and glycerol stocks. Isolates were biochemically characterized and purified isolates were test against pathogenic microorganisms for screening. Isolates with antagonistic properties were inoculated in production media and secondary metabolites or antimicrobial products were extracted. Result: The seven actinomycetes strains showing maximum antibacterial activity were isolated further characterized based on their colony characteristics and biochemical analyses. The isolates were screened for their secondary metabolites activity on three human pathogenic bacteria are Escherichia coli (E. coli), Methicillin-Resistant Staphylococcus aureus (S. aureus) and Vancomycin-Resistant Enterococci (VRE). Discussion: The strain MITS 1005 was found to be more active against the test bacteria. Contents lists available at ScienceDirect