EPS-mediated biosynthesis of nanoparticles by Bacillus stratosphericus A07, their characterization and potential application in azo dye degradation.

Microbial exopolysaccharides (EPS) are biocompatible, biodegradable, and less toxic substances secreted outside the cell. They adsorb metal cations to its surface, making it another captivating property, which helps in stabilizing and biosynthesizing metal nanoparticles. Owing to these properties, we adopted bacterial EPS toward the green synthesis of nanoparticles and its application in the removal of azo dyes. Extracted EPS weighed 2.6 mg/mL from the most potential isolate A07 with 385 µg/mg of the carbohydrate content. The top three isolates were subjected to nanoparticle synthesis via the intracellular method and, by their extracted EPS, silver nanoparticles (AgNP) with the size around 87 nm were successfully produced by both methods mediated by the most potent isolate. The nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction studies, atomic force microscopy, and FT-IR analysis. The nanoparticles were employed for dye degradation of azo dyes, namely, Methyl Orange (MO) and Congo Red (CO). EPS-Ag NPs showed fair degradation capability determined by UV-Vis kinetic studies. The work suggests electron transfer from reducing agent to dye molecule mediated by nanoparticles, destroying the dye chromophore. This makes EPS-Ag NPs a suitable, cheap, and environment-friendly candidate for biodegradation of harmful azo dyes. The most potential isolate was identified as Bacillus stratosphericus by 16S rRNA sequencing and submitted to GenBank under the accession id MK968439.

Unraveling a natural protease inhibitor from marine Streptomyces griseoincarnatus HK12 active against Chikungunya virus.

Proteases play an indispensable role in the life cycles of several life-threatening organisms such as the ones causing malaria, cancer and AIDS. A targeted blockade of these enzymes could be an efficient approach for drug modeling against these causative agents. Our study was directed towards the extraction and characterization of a protease inhibitor having activity against Chikungunya virus (CHIKV). A protein-based protease inhibitor (PI) in Streptomyces griseoincarnatus HK12 with anti-viral activity against CHIKV was revealed when screened against two major proteases, papain and trypsin. The PI was efficiently extracted at 60 % ammonium sulfate saturation and purified by ion-exchange chromatography (CM-Sepharose) at 300 mM NaCl elution followed by SDS-PAGE (10 %). The protein was characterized by denaturing SDS-PAGE, reverse zymography, and MALDI-TOF peptide mass fingerprinting. The protein-based PI was studied to have a high molecular weight of 66-70 kDA. The PI was tested to supress the supress cytopathic effects (CPE) exerted by the clinically isolated virus in BHK21 cells. This was used as a measure to determine the antiviral activity. The PI exerted significant effects with an effective concentration calculated as EC50 11.21 µg/mL. The protein was found to be reported as the first of its kind which also stands out to be the first a natural protease inhibitor against the treatment of the chikungunya virus.

An ex-situ and in vitro approach towards the bioremediation of carcinogenic hexavalent chromium.

Chromium, ranking the second most among toxic heavy metal pollutants in the world, causing respiratory, cardiovascular and renal problems in human beings is under study herein. We examined the biological remediation of the carcinogenic Cr (VI) polluted soils by indigenous yeast isolates. The total element analysis of the treated sample was determined by Energy Dispersion X-ray Micro Analysis (EDXMA). The sample under study was observed to have a high concentration of 458.29 mgKg-1 Cr (VI), determined by Atomic Absorption Spectroscopy (AAS) and DPC analysis. The most tolerant isolate designated as CSR was used for in vitro and ex-situ bioremediation studies of Cr (VI). The isolate achieved significant bioremediation of 86% in vitro and 75.12% in ex-situ method. The optimal conditions for in vitro bioremediation were found to be 28 °C and a pH of 6. The ITS1, 5.8S rRNA and D1, D2 domain of LSU rRNA gene characterization of the isolate CSR illustrated that it belongs to Ustilago genera. The isolate was deposited in NCBI GenBank as Ustilago sp. CSR (KY284846). Although, Ustilago is generally a pathogenic fungus, our study opens up the scope of using Ustilago spp. for bioremediation of the carcinogenic heavy metal Chromium.

Fatty acyl compounds from marine Streptomyces griseoincarnatus strain HK12 against two major bio-film forming nosocomial pathogens; an in vitro and in silico approach.

The perpetual increase in the resistance offered by biofilm-forming nosocomial pathogens has become a critical clinical challenge. Marine Streptomyces sps present a promising future of novel compounds with novel applications. We focus on the anti-biofilm activity of marine Streptomyces against two major nosocomial pathogens from clinical samples, Pseudomonas aeruginosa and Staphylococcus aureus. Herein, Streptomyces griseoincarnatus, a species known to harbour alkaline protease inhibitors and anti-tumour compounds were found to exhibit anti-biofilm activity. The study progresses to decipher the anti-biofilm potential of the extract as 82.657 ±â€¯1.1002% against P. aeruginosa and 78.973 ±â€¯1.672% against S. aureus at 100 µg/mL. The strain under study, S. griseoincarnatus HK 12 (accession no MF100857) has revealed the presence of certain fatty acyl compounds namely, 13Z-Octadecenal, 9Z-Octadecenal, Arachidic acid, Tetracosanoic acid and Erucic acid by GC-MS screening. Furthermore, the active compounds were docked against the quorum sensing system, LasI. The compound 13Z-Octadecenal was found to bind to the conserved sites of substrate binding with a binding energy of -1.90 kcal/mol thus, affirming the inhibitory activity of the fatty acyl compound. These active compounds were previously reported to be a part of active extracts exhibiting relevant antagonistic activities, but this so far is the first time they are found possessing anti-biofilm activity. Interestingly, the toxicity level of the extract at a high concentration of 500 µg/mL is as low as 11.5% when tested against human lung cancer lines, A549. Thus the report highlights the evidence of the potential of S griseoincarnatus HK12 to be an active and safe anti-biofilm agent.

Biofilm inhibition formation of clinical strains of Pseudomonas aeruginosa mutans, photocatalytic activity of azo dye and GC-MS analysis of leaves of Lagerstroemia speciosa.

The investigation was conducted to analyse the bioactive compounds from the leaf extracts of L. speciosa by GC-MS. The extracts were screened for antibacterial and antibiofilm activities against potential clinical strains. The bioactive compounds from the leaves of L. speciosa were extracted by soxhlet continuous extraction method and their chemical composition was analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). The antibacterial activity was evaluated against clinical strain like Staphylococcus aureus, Escherichia coli, P. aeruginosa and Salmonella typhi by well diffusion technique. We also screened for antibacterial property against common food borne pathogens namely Listeria monocytogenes and Bacillus cereus at varied concentration 250µml-1 to 1000µml-1. Thereafter antibiofilm assay was carried out at from 250 to 1000µg/ml against P. aeruginosa (high biofilm forming pathogen) clinical strain by cover slip technique and the morphology of the pathogen was observed using Scanning Electron Microscopy-(SEM). It was observed that diverse class of secondary metabolites were found by GC-MS analysis for all the extracts upon the continuous extraction. It was found that only minimum inhibition was seen in alcoholic extract for antibacterial activity, whereas all other extracts showed negligible activity. P. aeruginosa biofilm inhibited to 93.0±2% and 91±2% at higher concentration (1000µg/ml) for methanolic and ethanolic extract respectively. Absence of extracellular matrix structure and the surface cracking of biofilm were viewed by SEM, which confirmed the antibiofilm activity. Hence this study reveals that L. speciosa showed significant antibiofilm activity against P. aeruginosa due to the phytoconstituents present in the leaf extracts which was well documented in the alcoholic extracts by GC-MS analysis. The methanolic and ethanolic extract showed good photocatalytic activity of 77.44% and 96.66% against azo dye degradation respectively. Further, isolating the novel phyto-compounds would yield better promising biological activities.

Phytoremediation of dyes using Lagerstroemia speciosa mediated silver nanoparticles and its biofilm activity against clinical strains Pseudomonas aeruginosa.

The aim of this study was to prepare silver nanoparticles by a green method using the aqueous leaves extract of Lagerstroemia speciosa. The prepared silver nanoparticles were characterized, studied for its photocatalytic and biofilm inhibition studies. The maximum absorbance peak was found at 427nm and thus confirming the formation of silver nanoparticles. The average size of silver nanoparticles synthesized was found to be 12nm using XRD and it was spherical in shape. The nanoparticles synthesized was investigated for photocatalytic activity for to two different dye molecules, methyl orange and methylene blue showing 310 and 290min degradation time respectively. The silver nanoparticles biofilm inhibition assay against clinical strains of Pseudomonas aeruginosa showed lowest accumulation at a lower concentration. The biofilm inhibition was also studied by visual interpretation through Scanning Electron Microscopy states that 50µgmL-1 exerts the highest inhibition compared against the control. This evident helps to analysis the silver nanoparticles for various applications in future.