Enzymatic biodegradation, kinetic study, and detoxification of Reactive Red-195 by Halomonas meridiana isolated from Marine Sediments of Andaman Sea, India.

Azo dyes are a significant class of hazardous chemicals that are extensively utilised in diverse industries. Industries that manufacture and consume reactive azo dyes generate hyper-saline wastewater. The ability of halotolerant bacteria to thrive under extreme environmental conditions thus makes them a potential candidate for reactive azo dye degradation. An efficient halotolerant bacterium (isolate SAIBP-6) with the capability to degrade 87.15% of azo dye Reactive Red 195 (RR-195) was isolated from sea sediment and identified as Halomonas meridiana SAIBP-6. Strain SAIBP-6 maintained potential decolourisation under a wide range of environmental conditions viz. 35-45°C temperature, 50-450 mg/L RR-195, pH 7-9, and 50-150 g/L NaCl. However, maximum decolourisation occurred at 40°C, 200 mg/L RR-195 dye, pH 9, and 50 g/L NaCl, under static conditions. Tyrosinase and azoreductase were responsible for dye degradation. The reaction catalysed by these enzymes followed zero-order kinetics. The maximum velocity (Vmax) of the enzymatic reaction was 4.221 mg/(L.h) and the Michaelis constant (Km) was 517.982 mg/L. Strain SAIBP-6 also efficiently decolourised Reactive Black-5 and Reactive Yellow-160 dye. The biodegradation process was further studied with the help of UV-Vis spectral scan, ultra-high performance liquid chromatography (UPLC), fourier-transform infra-red spectroscopy (FT-IR), and proton nuclear magnetic resonance (1H NMR) analysis. Finally, cytogenotoxicity assay conducted with the meristematic root tip cells of Allium cepa and phytotoxicity assay conducted with the seeds of Vigna mungo led to the inference that strain SAIBP-6 significantly reduced the toxicity of RR-195 after biodegradation.

Postprandial anti-hyperglycemic activity of marine Streptomyces coelicoflavus SRBVIT13 mediated gold nanoparticles in streptozotocin induced diabetic male albino Wister rats.

The present study focuses on the biosynthesis of gold nanoparticles (AuNPs) using Streptomyces coelicoflavus (S. coelicoflavus) SRBVIT13 isolated from marine salt pan soils collected from Ongole, Andhra Pradesh, India. The biosynthesised AuNPs are characterised by UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray analysis. Transmission electron microscopy study suggests that the biosynthesised AuNPs are spherical in shape within a size range of 12-20 nm (mean diameter as 14 nm). The anti-type II diabetes activity of AuNPs is carried out by testing it in vitro α-glucosidase and α-amylase enzyme inhibition activity and in vivo postprandial anti-hyperglycemic activity in sucrose and glucose-loaded streptozotocin induced diabetic albino Wister rats. AuNPs has shown a significant inhibitory activity of 84.70 and 87.82% with IC50 values of 67.65 and 65.59 µg/mL to α-glucosidase and α-amylase enzymes, while the diabetic rats have shown significant reduction in the post postprandial blood glucose level by 57.80 and 88.09%, respectively compared with control group after AuNPs treatment at the concentration of 300 and 600 mg/kg body weight. Hence, this biosynthesised AuNPs might be useful in combating type II diabetes mellitus for the betterment of human life.

Aquatic model for engine oil degradation by rhamnolipid producing Nocardiopsis VITSISB.

The present study was focused on isolation, screening, characterization and application of biosurfactant producing marine actinobacteria. Twenty actinobacteria were isolated from marine water sample and were primarily screened for biosurfactant production using hemolytic activity method. Among the 20 isolates, six showed positive result for hemolytic activity and those were taken for further secondary screening tests such as oil collapse method, oil spreading method and emulsification method. From the results of secondary screening analysis, two isolates (SIS-3 and SIS-20) were selected and further used to carry out biosurfactant characterization test such as pH, density, surface tension and viscosity determination. Comparing biosurfactant characterization results, SIS-3 was chosen for further analysis and application. FT-IR and GC-MS were carried out for analysis of biosurfactant from isolate SIS-3 and the compound detected was rhamnolipid. The isolate (SIS-3) was identified as Nocardiopsis using 16S rRNA gene sequencing and named as 'Nocardiopsis VITSISB' (KC958579) which was further applied for immobilizing whole cells for engine oil degradation by constructing an aquatic model and using natural products such as soybean meal, sugarcane juice as nutrient source. The oil was efficiently degraded by rhamnolipid producing Nocardiopsis VITSISB (KC958579) within 25 days which indicated that the strain can act as a natural candidate for the bioremediation of oil spill in ocean.

Statistical media optimization and cellulase production from marine Bacillus VITRKHB.

Marine Bacillus species are potent producers of novel enzymes. Marine Bacillus VITRKHB was observed to be efficient for cellulolytic activity. It was employed for the production of extracellular cellulase. Cellulase was partially purified to 1.6-fold in a stepwise manner by ammonium sulfate precipitation, dialysis, and DEAE ion exchange chromatography. The molecular weight of purified protein was found to be about 33 kDa by SDS-PAGE. Its specific activity was recorded as 1.92 IU/mg. The effect of various carbon and nitrogen sources on cellulase production was investigated. The maximum enzyme activity was recorded in the fermentation media containing xylose as carbon source and beef extract as nitrogen source. The combined interactive effect of different variables on cellulase production was studied by response surface methodology. The optimized combination of variables for maximum enzyme activity was determined as; xylose 5.0 %, beef extract 6.9 %, pH 7.83, NaCl 1.17, and temperature 25.84 °C, after 24 h of incubation.

Antioxidant activity of newly discovered lineage of marine actinobacteria.

OBJECTIVE: To investigate the antioxidant activity of marine actinobacteria. METHODS: The content of total phenolics, the level of antioxidant potential by DPPH radical scavenging activity, metal chelating activity, FRAP method, ß carotene assay and NO scavenging activity in extract were determined. RESULTS: In all the methods the extract exhibited good scavenging activity except NO scavenging activity. The IC(50) values of marine actinobacteria extract on DPPH radical were found to be 41.09 µg/mL. The zone of color retention was 12 mm in ß-carotene bleaching assay. DNA protective efficiency of the extracts was also studied using UV-photolysed H(2)O(2)-driven oxidative damage to pBR322. HPLC analysis identified some of the major phenolic compounds in extracts, which might be responsible for the antioxidant potential and cyto-protection. It showed a 100% cytotoxic effect in brine shrimp lethality assay within 10 mins. The novel actinobacteria was identified as Streptomyces LK-3 (JF710608) through 16S rDNA Sequencing. CONCLUSIONS: The results obtained suggest that the extracts bear anti-cancer metabolites and could be considered as a potential source for anti-cancer drug development.