Isolation and partial purification of erythromycin from alkaliphilic Streptomyces werraensis isolated from Rajkot, India

AbstractAn alkaliphilic actinomycete, BCI-1, was isolated from soil samples collected from Saurashtra University campus, Gujarat. Isolated strain was identified as Streptomyces werraensis based on morphological, biochemical and phylogenetic analysis. Maximum antibiotic production was obtained in media containing sucrose 2%, Yeast extract 1.5%, and NaCl 2.5% at pH 9.0 for 7 days at 30 °C. Maximum inhibitory compound was produced at pH 9 and at 30 °C. FTIR revealed imine, amine, alkane (CC) of aromatic ring and p-di substituted benzene, whereas HPLC analysis of partially purified compound and library search confirmed 95% peaks matches with erythromycin. Chloroform extracted isolated compound showed MIC values 1 μg/ml against Bacillus subtilis, ≤0.5 μg/ml against Staphylococcus aureus, ≤0.5 μg/ml against Escherichia coli and 2.0 μg/ml against Serretia GSD2 sp., which is more effective in comparison to ehtylacetate and methanol extracted compounds. The study holds significance as only few alkaliphilic actinomycetes have been explored for their antimicrobial potential

Life History Responses and Gene Expression Profiles of the Nematode Pristionchus pacificus Cultured on Cryptococcus Yeasts.

Nematodes, the earth's most abundant metazoa are found in all ecosystems. In order to survive in diverse environments, they have evolved distinct feeding strategies and they can use different food sources. While some nematodes are specialists, including parasites of plants and animals, others such as Pristionchus pacificus are omnivorous feeders, which can live on a diet of bacteria, protozoans, fungi or yeast. In the wild, P. pacificus is often found in a necromenic association with beetles and is known to be able to feed on a variety of microbes as well as on nematode prey. However, in laboratory studies Escherichia coli OP50 has been used as standard food source, similar to investigations in Caenorhabditis elegans and it is unclear to what extent this biases the obtained results and how relevant findings are in real nature. To gain first insight into the variation in traits induced by a non-bacterial food source, we study Pristionchus-fungi interactions under laboratory conditions. After screening different yeast strains, we were able to maintain P. pacificus for at least 50-60 generations on Cryptococcus albidus and Cryptococcus curvatus. We describe life history traits of P. pacificus on both yeast strains, including developmental timing, survival and brood size. Despite a slight developmental delay and problems to digest yeast cells, which are both reflected at a transcriptomic level, all analyses support the potential of Cryptococcus strains as food source for P. pacificus. In summary, our work establishes two Cryptococcus strains as alternative food source for P. pacificus and shows change in various developmental, physiological and morphological traits, including the transcriptomic profiles

Life history traits of <i>P</i>. <i>pacificus</i> cultured on the yeasts <i>C</i>. <i>albidus</i> and C. <i>curvatus</i>.

<p>The boxplots show the median, first and third quartile values from different life history traits experiments. A) Brood size of <i>P</i>. <i>pacificus</i> grown on <i>C</i>. <i>albidus</i> (C3), <i>C</i>. <i>curvatus</i> (C5) and <i>E</i>. <i>coli</i> OP50. Brood size was calculated as average number of progeny of 10 J4 larvae. B) Pharyngeal pumping rate results of <i>P</i>. <i>pacificus</i> exposed to <i>Cryptococcus</i> species. Assay was performed using <i>E</i>. <i>coli</i> OP50 as control. C) Defecation time (10 mins) of <i>P</i>. <i>pacificus</i> exposed to <i>C</i>. <i>albidus</i> (C3) and <i>C</i>. <i>curvatus</i> (C5) using <i>E</i>. <i>coli</i> OP50 as control. D) Eurystomatous (Eu) ratio of <i>P</i>. <i>pacificus</i> adults grown on <i>C</i>. <i>albidus</i> (C3) and <i>C</i>. <i>curvatus</i> (C5). Eu ratio was calculated from five biological replicates. Statistical significance was calculated using student t-test.</p

Differential Interference Contrast microscopy (DIC) to study nature of yeast clumps.

<p>A) Yeast cells clumps of <i>C</i>. <i>albidus (C3)</i> in intestine of <i>P</i>. <i>pacificus</i>. B), C) Absence of yeast clumps in defecated worms after 3 hours off food, suggesting that yeasts cells can be fully digested or excreted by <i>P</i>. <i>pacificus</i>.</p

Developmental timing and survival curves of <i>P</i>. <i>pacificus</i> after exposure to <i>C</i>. <i>albidus</i> and <i>C</i>. <i>curvatus</i>.

<p>A) The boxplots show the time needed for <i>P</i>. <i>pacificus</i> nematodes to enter different developmental stage when growing on <i>E</i>. <i>coli</i> OP50 or <i>Cryptococcus</i> strains. The inlay shows the individual data points representing ten plates per food source. B) Survival of <i>P</i>. <i>pacificus</i> exposed to <i>C</i>. <i>albidus</i> (C3) and <i>C</i>. <i>curvatus</i> (C5) for 10 days. Standard lab food <i>E</i>. <i>coli</i> OP50 was used as a control.</p

Gene expressions profiling of <i>P</i>. <i>pacificus</i> after a <i>Cryptoccocus</i> or <i>E</i>. <i>coli</i> diet.

<p>A) PCA of transcriptomes obtained from <i>P</i>. <i>pacificus</i> adult worms growing on <i>C</i>. <i>albidus</i> (C3), <i>C</i>. <i>curvatus</i> (C5) and <i>E</i>. <i>coli</i> OP50. Despite substantial variation in the control samples grown on <i>E</i>. <i>coli</i> OP50, different samples cluster together according to their food source indicating robust expression changes under different environments. B) Genes that are down-regulated upon <i>Cryptococcus</i> diet show a bias towards higher expression at early developmental stages. The graph shows mean expression and standard error of down-regulated genes in 10 developmental transcriptomes representing dauer, J2, J3, J4, and adult worms. C) Genes that are up regulated upon <i>Cryptococcus</i> tend to reflect transcriptomes from later developmental stages. D) Enrichment of significantly differentially expressed genes upon exposure to <i>C</i>. <i>albidus (C3)</i> in previous gene expression profiling studies. E) Enrichment of significantly differentially expressed genes upon exposure to <i>C</i>. <i>curvatus (C5)</i> in previous gene expression profiling studies. F) KEGG pathway enrichment of down-regulated genes under exposure to <i>C</i>. <i>albidus (C3)</i>. The x-axis shows the enrichment score indicating how much more genes of a given pathway are found as differentially expressed when compared to random gene sets. The y-axis shows the negative logarithm of the p-value indicating the significance of the overrepresentation. G) KEGG pathway enrichment of up-regulated genes under exposure to <i>C</i>. <i>albidus</i> (C3). H) Enrichment of KEGG pathways among down-regulated genes when fed with <i>C</i>. <i>curvatus</i> (C5). I) Enrichment of KEGG pathways among up-regulated genes after exposure to <i>C</i>. <i>curvatus</i> (C5).</p