RESEARCH ARTICLE Isolation, Purification and Partial Characterization of an Antifungal Agent Produced by Salt-tolerant Alkaliphilic Streptomyces violascens IN2-10 Gajraj Singh Bisht • Alpana Bharti • Vijay Kumar • Omprakash Gusain Received: 28 June 2012 / Revised: 8 August 2012 / Accepted: 23 August 2012 / Published online: 14 September 2012 Ó The National Academy of Sciences, India 2012 Abstract An actinobacterium strain designated as IN2-10 was isolated from Garhwal region. IN2-10 was subjected to polyphasic characterization. The organism produced white to cream colored aerial mycelium with brown diffusible pigment. This isolate showed growth at 11 % NaCl, pH 4–10, and a temperature range of 15–37 °C. The isolate IN2-10 was found to belong to the genus Streptomyces and it was closely related to Streptomyces violascens (98.57 %, 16S rDNA). Of the various media tested, the high yield of active metabolite for isolate was observed in glucose soyabean meal medium at pH 10, with salt concentration of 3 % (w/v) and at a temperature of 37 °C. The broad spectrum antifungal activity of metabolite was observed against yeasts (Candida albicans, C. parapsilosis, and C. tropicalis) as well as molds (Microsporum gypseum, M. canis , Trichophtyton rubrum, Aspergillus flavus, A. fumiga- tus, and A. niger). The active metabolite produced by the strain was partially characterized and was found to belong to the heptaene group of polyene class of antifungal agents. In view of the decline in the discovery of new lead com- pounds in recent years, further investigations would require to lead to some useful products. Keywords Streptomyces violascens Á Antifungal activity Á Polyene class Á Alkaliphilic Introduction The discovery of new antibiotics and other bioactive microbial metabolites continues to be an important objec- tive in new drug research because of the toxicity of some currently used compounds and the emergence of resistance among fungal pathogens [1]. The problems of drug resis- tance, patient’s sensitivity, and inability to control certain infectious diseases have given an impetus to continuous search for new antibiotics all over the world. To combat the multidrug resistant organisms, introduction of new anti- microbial compounds or antibiotics is essential [2]. The search for new and safe antifungal agents with greater potency is a major challenge to the pharmaceutical industry today, especially with the increase in opportunistic infec- tions in the immuno-compromised host. However, the search for antifungal compounds has been progressing slowly [3]. The reason for the slow progress compared to antibacterials is that, like mammalian cells, fungi are eukaryotic so there are less number of specific targets for an antifungal agent. The history of new drug discovery shows that novel skeletons have come, in the majority of cases, from actinomycetes [4]. Actinomycetes have pro- vided important bioactive compounds of high commercial value and continue to be routinely screened for new bio- active substances [5]. The vast majority of actinomycetes have originated from soil [6]. These searches have been remarkably successful and approximately two-third of naturally occurring antibiotics, including many of medical importance, have been isolated from actinomycetes [7], especially from Streptomycetes and also from some rare actinomycetes (non-Streptomycetes). Streptomyces species are widely recognized as industrially important microor- ganisms because of their ability to produce many kinds of novel secondary metabolites including antibiotics [2]. G. S. Bisht (&) Á A. Bharti Á V. Kumar Department of Microbiology, Sardar Bhagwan Singh Post Graduate Institute of Biomedical Sciences and Research, Balawala, Dehradun 248161, Uttarakhand, India e-mail: grsbisht@gmail.com O. Gusain Department of Zoology and Biotechnology, H.N.B. Garhwal University, Srinagar, Uttarakhand, India 123 Proc. Natl. Acad. Sci., India, Sect. B Biol. Sci. (January–March 2013) 83(1):109–117 DOI 10.1007/s40011-012-0086-1