The lipopeptides produced by Gram-positive strains Sunitinib mouse have been classified into various types based on their amino acid composition and fatty acid chain length [14]. Similarly, lipopeptides of Pseudomonas also have been grouped into different groups including amphisin, syringomycin, tolaasin and viscosin based on the number and composition of amino acids [13, 15, 16]. Among the several types of biosurfactants, lipopeptides belonging to iturins [17], surfactins, [18], fengycins

[19], kurstakins [20], bacillomycins [21] and mycosubtilin [22] displayed therapeutic applications [23] and they were never reported to produce by any Gram-negative bacteria. Therefore, in the present study we have isolated few Gram-negative bacterial strains belonging to genera Citrobacter and Enterobacter producing antimicrobial lipopeptides from a fecal contaminated soil sample. Further, detailed characterization of these antimicrobial lipopeptides assigned them to iturins, fengycins, kurstakins and surfactins, usually produced by Gram-positive bacteria. Results Identification of the buy Palbociclib lipopeptide producing strains Nine antimicrobial producing strains were isolated from a fecal contaminated soil sample during a screen to isolate the bacteriocin producing bacteria. The colonies were selected based on colony morphology and the zone of clearance in their surroundings that might be formed

due to the activity of antimicrobial substances produced by the strain (Figure 1A). The isolates grew well on tryptone soya agar (TSA) between pH 5.0 to 9.0 and up to 42°C temperature with optimum growth at 37°C. All strains were rod shaped, facultative anaerobes, showed positive reaction to catalase and negative for oxidase activities. The 16S rRNA gene sequence BLAST analysis revealed high identity with Citrobacter farmeri for strains S-3, S-6 and S-7. Other strains including S-4, S-5 and S-9 had identity with different species of the MRIP genus Enterobacter. Strains S-10, S-11 and S-12 showed high similarity with E. cloacae subsp. dissolvens. Further, Phylogenetic analysis with close relatives also assigned them to genera Citrobacter

and Enterobacter of the family Enterobacteriaceae. In neighbour-joining phylogenetic tree, strains S-3, S-6 and S-7 formed a cluster with C. farmeri and C. amalonaticus (Figure 2). Although isolate S-9 showed 98.1% identity with E. mori in 16S rRNA gene blast analysis, it formed an out group to the clade containing E. hormaechei and E. mori with low bootstrap value. Overall, most of the clusters of the neighbour-joining phylogenetic tree showed low bootstrap values. Figure 1 Screening of isolates for antimicrobial activity. (A) colonies showing zone of clearance (B) well diffusion assay of methanol extracts. Selected colonies were purified and preserved. Further, methanol extracts were prepared from 48 h cell free fermented broth of all selected isolates and tested against S. aureus (MTCC1430).