With the increased number of cholera outbreaks and emergence of multidrug resistance in Vibrio cholerae strains it has become necessary for the scientific community to devise and develop novel therapeutic approaches against cholera. Recent studies have indicated plausibility of therapeutic application of metal nano-materials. Among these, silver nanoparticles (AgNPs) have emerged as a potential antimicrobial agent to combat infectious diseases. At present nanoparticles are mostly produced using physical or chemical techniques which are toxic and hazardous. Thus exploitation of microbial systems could be a green eco-friendly approach for the synthesis of nanoparticles having similar or even better antimicrobial activity and biocompatibility. Hence, it would be worth to explore the possibility of utilization of microbial silver nanoparticles and their conjugates as potential novel therapeutic agent against infectious diseases like cholera. The present study attempted utilization of Ochrobactrum rhizosphaerae for the production of AgNPs and focused on investigating their role as antimicrobial agents against cholera. Later the exopolymer, purified from the culture supernatant, was used for the synthesis of spherical shaped AgNPs of around 10 nm size. Further the exopolymer was characterized as glycolipoprotein (GLP). Antibacterial activity of the novel GLP–AgNPs conjugate was evaluated by minimum inhibitory concentration, XTT reduction assay, scanning electron microscopy (SEM) and growth curve analysis. SEM studies revealed that AgNPs treatment resulted in intracellular contents leakage and cell lysis. The potential of microbially synthesized nanoparticles, as novel therapeutic agents, is still relatively less explored. In fact, the present study first time demonstrated that a glycolipoprotein secreted by the O. rhizosphaerae strain can be exploited for production of AgNPs which can further be employed to treat infectious diseases. Although this type of polymer has been obtained earlier from marine fungi and bacteria, none of these reports have studied the role of this polymer in AgNPs synthesis and its application in cholera therapy. Interestingly, the microbial GLP-capped AgNPs exhibited antibacterial activity against V. cholerae comparable to ciprofloxacin. Thus the present study may open up new avenues for development of novel therapeutic agents for treatment of infectious diseases.

In an attempt to screen out cellulase producing bacteria from herbivorous animal fecal matter it was possible to isolate a potent bacterium from cow dung. The bacterium was identified as Bacillus sp. using 16S rDNA based molecular phylogenetic approach. The effect of different agricultural wastes, paper wastes and carboxymethyl cellulose on endoglucanase production was tested and was found to produce maximally at 8% carboxymethyl cellulose. The endoglucanase was precipitated by ammonium sulfate saturation and purified by DEAE- Sepharose column. The purification was achieved 8.5 fold from the crude extract with a yield of 68.1%. The molecular weight of the protein was determined to be 97 kDa by SDS-PAGE. The enzymatic activity was moderately reduced by detergents (SDS, Tween-80), metal ions (MnCl₂, ZnCl₂) and EDTA. The endoglucanase was stable between pH 5.0 – 9.0 and temperature between 20−70°C with optimal activity at pH 7.0 and temperature 50°C. The apparent Km value of the enzyme for the substrate carboxymethyl cellulose was recorded to be 0.25 mg/ml. The endoglucanase was stable in the presence of commercial detergents such as Ariel, Surf Excel and Tide, indicated might be of potential applications in detergent industry. The enzyme from this strain could also be applied in bioconversion of lignocellulosic biomass into fermentable sugars.

A buff-yellow-pigmented bacterium, strain K22-20^T, which was isolated from a cold desert of the Indian Himalayas, was subjected to a polyphasic taxonomic study. Phenotypic and chemical properties of strain K22-20^Twere consistent with its classification in the genusOrnithinimicrobium. The major fatty acids of the strain were iso-C_17 : 1ω9c(cis-15-methyl 7-hexadecenoic acid), iso-C_15 : 0(13-methyl tetradecanoic acid), iso-C_16 : 0(14-methyl pentadecanoic acid) and iso-C_17 : 0(15-methyl hexadecanoic acid). The G+C content of the genomic DNA was 71 mol%. According to 16S rRNA gene sequence analysis, strain K22-20^Twas closely related toOrnithinimicrobium humiphilumHKI 0124^T(97.7 %). However, genomic relatedness between strain K22-20^TandO. humiphilumMTCC 6406^T, as revealed by DNA–DNA hybridization, was 64.5 %. Based on the polyphasic data, strain K22-20^T(=MTCC 6545^T=DSM 17687^T=JCM 12763^T) represents a novel species of the genusOrnithinimicrobium, for which the nameOrnithinimicrobium kibberensesp. nov. is proposed.

A reddish orange bacterium, strain K07-05^T, was isolated from soil during a study of the bacterial diversity of a cold desert of the Indian Himalayas and was studied by using a polyphasic approach. The organism had morphological and chemotaxonomic properties consistent with its classification in the genusKocuria. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain K07-05^Twas closely related toKocuria roseaDSM 20447^TandKocuria polarisMTCC 3702^T(98.1 and 97.8 % sequence similarity, respectively), whereas the sequence similarity values with respect to the otherKocuriaspecies with validly published names were between 96.4 and 94.2 %. However, the genomic relatedness, as shown by DNA–DNA hybridization, of strain K07-05^TandK. polarisMTCC 3702^Tis 49.5 % and that withK. roseaMTCC 2522^Tis 24.0 %. The DNA G+C content of the strain is 75.3 mol%. The above data in combination with the phenotypic distinctiveness of K07-05^Tclearly indicate that the strain represents a novel species, for which the nameKocuria himachalensissp. nov. is proposed. The type strain is K07-05^T(=MTCC 7020^T=DSM 44905^T=JCM 13326^T).

The taxonomic position of a lemon-yellow-pigmented actinobacterium, strain K22-21^T, isolated from a soil sample from Lahaul-Spiti Valley in the Indian Himalayas, was determined using a polyphasic approach. The strain had phenotypic and chemical properties that were consistent with its classification in the genusAgrococcus. Alignment of the 16S rRNA gene sequence of strain K22-21^Twith sequences fromAgrococcus jenensisDSM 9580^T,Agrococcus baldriDSM 14215^TandAgrococcus citreusDSM 12453^Trevealed similarities of 98.5, 96.8 and 96.6 %, respectively. However, the level of DNA–DNA relatedness between strain K22-21^TandA. jenensiswas 55.1 %. The novel strain could be distinguished from type strains of the three species of the genusAgrococcususing DNA–DNA relatedness and phenotypic data. Based on these differences, strain K22-21^T(=MTCC 7154^T=DSM 17612^T) should be classified as the type strain of a novel species ofAgrococcus, for which the nameAgrococcus lahaulensissp. nov. is proposed.