BackgroundSerratiopeptidase is an alkaline metalloendopeptidase, which acquired wide significance because of its therapeutic applications. The present study was undertaken for purification, characterization, and structural elucidation of serratiopeptidase produced from Streptomyces hydrogenans var. MGS13.ResultThe crude enzyme was purified by precipitating with ammonium sulfate, dialysis, and Sephadex gel filtration, resulting in 34% recovery with a 12% purification fold. The purified enzyme S.AMP13 was spotted as a single clear hydrolytic band on casein zymogram and whose molecular weight was found to be 32 kDa by SDS-PAGE. The inhibitor and stability studies revealed that this enzyme is metalloprotease, thermostable, and alkaline in nature. The maximum serratiopeptidase activity was observed at 37 °C and pH 9.0. The partial amino acid sequence of the purified enzyme S.AMP13 by LC-MS/MS analysis shows the closest sequence similarities with previously reported alkaline metalloendopeptidases. The amino acid sequence alignment of S.AMP13 shared a conserved C-terminus region with peptidase-M10 serralysin superfamily at amino acid positions 128–147, i.e., ANLSTRATDTVYGFNSTAGR revealed that this enzyme is a serralysin-like protease. The kinetic studies of the purified enzyme revealed a Km of 1 mg/mL for its substrate casein and Vmax of 319 U/mL/min. The 3D structure of the purified enzyme was modeled by using SWISS-MODEL, and the quality of the structure was authenticated by assessing the Ramachandran plot using PROCHECK server, which suggested that the enzyme was stable with good quality.ConclusionInhibitor, stability, electrophoretic, and bioinformatic studies suggested that the purified enzyme obtained from S. hydrogenans var. MGS13 is a serralysin-like protease.Electronic supplementary materialThe online version of this article (10.1186/s43141-019-0002-7) contains supplementary material, which is available to authorized users.

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Objective: To isolate, screen and characterize antibiotic producing actinomycetes from Kapuluppada plastic waste dumping yard, Visakhapatnam.Methods: A total of 12 soil samples were collected, serially diluted and spread on starch casein agar supplemented with Rifampicin and Cycloheximide for inhibition of bacteria and fungi, respectively. Cross-streak method was used to check the antagonistic activity of isolated actinomycetes against bacteria and fungi. Crude extracts from submerged state fermentation were used for the production of antimicrobial compounds. Agar well diffusion method was used for antimicrobial activity of crude extracts against test organisms. The isolates were characterized by morphological, physiological and biochemical methods.

In the present study, we tested 83 actinomycete isolates for low density polyethylene (LDPE) degradation in the laboratory, and these isolates were previously isolated for biosurfactant production from the oil contaminated soil sample near Naval Dockyard in Visakhapatnam. Among them, 20 were positive using 2,3,5-triphenyl tetrazolium chloride (TTC) as a viability indicator and able to grow in a mineral salts medium containing LDPE as a sole source of carbon. Of these, NDYS-4 isolate showed prominent result with redox probe 2,3,5-triphenyltetrazolium chloride (TTC) as a viability indicator, which forms pink colour insoluble triphenylformazan (TPF) on mineral salts media containing emulsified polyethylene as a carbon source within five to seven days, and it was also grown prominently on mineral salt agar plates containing LDPE in comparison to other isolates, and it was selected for detailed analysis. The weight loss of polyethylene films was approximately 30% after four weeks of incubation with selected isolate. The viability and metabolic activity of this isolate growing on the polyethylene surface was confirmed using a TTC reduction test. The metabolic activity was also correlated with a concomitant increase in the protein density of the biomass on the surface of the polyethylene. The microbial degradation of LDPE was also analyzed by the change in pH of the culture media and microscopic analysis. Based on the results, this degradation may be mediated by enzymatic activity and may also involve cell-surface hydrophobicity. It was also able to grow on other polymers such as polyvinyl acetate (PVA), polycaprolactone (PCL), polyethylene oxide (PEO) and polyethylene glycol (PEG) using TTC as a viability indicator and also showed prominent growth on mineral salts agar plates containing polyethylene as a source of carbon. Based on the results of phenotypic characteristics, phylogenetic analysis, biochemical characteristics and 16S rRNA gene sequence homology, the isolate NDYS-4 was identified as Streptomyces coelicoflavus NBRC 15399 T . It could be concluded that the PE degrading actinomycete selected in this study showed diverse and varying capacities to degrade polyethylene and other polymers and can be exploited for cleaning up polyethylene contaminated sites.

Background: Type 2 diabetes mellitus (T2DM) is associated with a cluster of interrelated plasma lipid and lipoprotein abnormalities including reduced HDL cholesterol. Objective: To compare the lipid profile and new atherogenic indices among the coronary artery disease (CAD)-negative and-positive diabetic dyslipidemia subjects and determine the use of atherogenic indices in the early prediction of CAD in diabetic subjects. Materials and Methods: A total number of 194 subjects participated in our study, of which 65 people with diabetic dyslipidemia were considered cases and 129 nondiabetic people with normal lipid profile were considered control subjects based upon their fasting blood glucose (FBG) and lipid profiles. Furthermore, among the 65 cases, 38 subjects were identified as CAD negative and rest of the 27 subjects were CAD-positive subjects. Result: Lipid profiles of both CAD-negative and-positive diabetic subjects showed significantly different values than the control subjects except for high-density lipoprotein cholesterol (HDL-c) value (41.89 ± 1.49; p > 0.05) of CAD-negative subjects. The comparison between the CAD-negative and-positive diabetic dyslipidemia subjects observed significantly higher values of triglycerides (339.59 ± 52.24; p < 0.001) and very low-density lipoprotein cholesterol (VLDL-c) (67.91 ± 10.44; p < 0.001) and lower values of HDL-c (35.59 ± 1.40; p < 0.001) in CAD-positive subjects. When compared with control subjects, both CAD-negative and-positive subjects showed higher values of atherogenic indices that were significantly (p < 0.01 and p < 0.001, respectively) different. Conclusion: Our results indicate that atherogenic indices may be useful for identifying individuals at higher risk of cardiovascular disease in the clinical practices, especially, not markedly deranged or in centers with insufficient resources.