Antimicrobial investigation of selected soil actinomycetes isolated from unexplored regions of Kashmir Himalayas, India Aabid Manzoor Shah a, e , Shakeel-u-Rehman b , Aehtesham Hussain a, e , Saleem Mushtaq a , Muzafar Ahmad Rather c , Aiyatullah Shah a, e , Zahoor Ahmad c , Inshad Ali Khan d , Khursheed Ahmad Bhat b , Qazi Parvaiz Hassan a, * a Microbial Biotechnology Division, CSIReIndian Institute of Integrative Medicine, Sanatnagar, Srinagar, Jammu & Kashmir 190005, India b Medicinal Chemistry Division, CSIReIndian Institute of Integrative Medicine, Sanatnagar, Srinagar, Jammu & Kashmir 190005, India c Clinical Microbiology and PK/PD Division, CSIReIndian Institute of Integrative Medicine, Sanatnagar, Srinagar, Jammu & Kashmir 190005, India d Clinical Microbiology Division, CSIR- Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India e Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi 180 001, India article info Article history: Received 24 February 2017 Received in revised form 12 June 2017 Accepted 15 June 2017 Available online 22 June 2017 Keywords: Kashmir Himalayas Actinomycetes Antimicrobial activity Streptomyces pratensis IIIM06 Fermentation Actinomycin C complex Actiphenol abstract The aim of the present study was to isolate and evaluate the antimicrobial potential of soil actinomycetes of Kashmir Himalayas. The secondary metabolites of actinomycetes are the prominent source of anti- biotics. A total of 121 morphologically different actinomycete strains were isolated and screened for antimicrobial activity against various human pathogens. The ethyl acetate extract of fermented broth an actinomycete strain, identified as Streptomyces pratensis exhibited significant antimicrobial activity against Staphylococcus aureus ATCC 29213 with MIC 0.25 mg/ml and Mycobacterium tuberculosis Strain H37Rv with MIC 0.062 mg/ml. The strain S. pratensis IIIM06 was grown on large scale and their broth was extracted with ethyl acetate. The extract was subjected to various chromatography techniques which led to the isolation of four compounds whose structures were established as actinomycin C1, actinomycin C2, actinomycin C3 and actiphenol on the basis of spectral data analysis. Actinomycin C1, C2 and C3 exhibited potent antimicrobial activity against S. aureus as well as M. tuberculosis. The isolated indigenous acti- nomycetes exhibited good antibacterial activity and the study reveals that IIIM06 is a promising strain and could be of great potential for industrial applications. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction There is a continuous need for novel antibiotics to overcome the serious problem of evolving pathogens, naturally resistant bacteria and fungi and multidrug resistance among common bacterial pathogens [1e3]. Natural products have been regarded as an important source of antimicrobial compounds. From the past few decades the scaffolds of natural products discovered in the middle of the 20th century were used to form new antibiotics by semi- synthetic tailoring [4]. Natural sources are largely unexplored and could serve as a potential source for novel leads for drug discovery. Nearly 50,000 natural products have been discovered from micro- organisms. Over 10,000 of these are reported to have biological activity and more than 100 microbial products are in use today as antibiotics, antitumor agents, and agrochemicals [5]. Among mi- crobial sources, compounds of actinomycetes origin play a major role in drug discovery. A representative list of antibiotics with clinical significance produced by Actinomycetes are Kanamycin, Gentamycin, Neomycin, Streptomycin, Chloramphenicol, Novobi- ocin, Vancomycin, Teicoplanin, Erythromycin, Rifamycin, Chlortet- racycline, Oxy tetracycline, etc. Actinomycetes are gram positive unicellular branching group of bacteria known for their ability to produce bioactive secondary metabolites. Soil-based actinomycetes have been the source of countless drugs and have been intensively screened as an important source of therapeutically important molecules over a half century [6]. The frequency of discovering structurally novel compounds is decreasing these years and the findings seem to imply that the easily accessible microorganisms in soil had been exhausted and there is a need to hunt for microor- ganisms from unexplored sources. Exploring of new habitats is one of the most promising ways to isolate new strains of actinomycetes * Corresponding author. E-mail addresses: qphassan@iiim.ac.in, pervaizqazi@yahoo.com (Q.P. Hassan). Contents lists available at ScienceDirect Microbial Pathogenesis journal homepage: www.elsevier.com/locate/micpath http://dx.doi.org/10.1016/j.micpath.2017.06.017 0882-4010/© 2017 Elsevier Ltd. All rights reserved. Microbial Pathogenesis 110 (2017) 93e99