Ramasamy Balagurunathan

A study of the bactericidal, anti-biofouling, cytotoxic and antioxidant properties of actinobacterially synthesised silver nanoparticles.

Actinobacteria- mediated synthesis of silver nanoparticles (AgNPs) is a reliable, eco-friendly and important aspect of nanobiotechnology. In this study, aqueous silver ions, which were exposed to an actinobacterial biomass of Streptomyces naganishii (MA7), were reduced to form stable AgNPs under optimised conditions. The microbially synthesised AgNPs were characterised by UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM) and high- resolution transmission electron microscopy (HR-TEM). The size (5-50 nm) and shape (spherical) of the AgNPs were determined. The biosynthesised AgNPs exhibited good bactericidal, anti-biofouling, antioxidant and cytotoxic effects with regards to the HeLa cell line. A single protein band with a molecular weight of 44 kDa was obtained after partial purification of the culture filtrate via polyacrylamide gel electrophoresis. The potent actinobacterial strain was identified by its molecular (16s rRNA sequencing), phenotypic and cultural characteristics. The current study demonstrated the potential use of the extremophilic actinobacterial strain of S. naganishii (MA7) as a novel source for AgNPs synthesis with improved biomedical applications.

Biomedical potential of actinobacterially synthesized selenium nanoparticles with special reference to anti-biofilm, anti-oxidant, wound healing, cytotoxic and anti-viral activities.

Currently, there is an ever-increasing need to develop environmentally benign processes in place of synthetic protocols. As a result, researchers in the field of nanoparticle synthesis are focusing their attention on microbes from rare biological ecosystems. One potential actinobacterium, Streptomyces minutiscleroticus M10A62 isolated from a magnesite mine had the ability to synthesize selenium nanoparticles (SeNPs), extracellularly. Actinobacteria mediated SeNP synthesis were characterized by UV-visible, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and high resolution transmission electron microscopy (HR-TEM) analysis. The UV-spectral analysis of SeNPs indicated the maximum absorption at 510nm, FT-IR spectral analysis confirms the presence of capping protein, peptide, amine and amide groups. The selenium signals confirm the presence of SeNPs. All the diffraction peaks in the XRD pattern and HR-TEM confirm the size of SeNPs in the range of 10-250nm. Further, the anti-biofilm and antioxidant activity of the SeNPs increased proportionally with rise in concentration, and the test strains reduced to 75% at concentration of 3.2μg. Selenium showed significant anti-proliferative activity against HeLa and HepG2 cell lines. The wound healing activity of SeNPs reveals that 5% selenium oinment heals the excision wound of Wistar rats up to 85% within 18 days compared to the standard ointment. The biosynthesized SeNPs exhibited good antiviral activity against Dengue virus. The present study concludes that extremophilic actinobacterial strain was a novel source for SeNPs with versatile biomedical applications and larger studies are needed to quantify these observed effects of SeNPs.

Anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised silver nanoparticles using Coriandrum sativum leaf extract.

In this present investigation, AgNPs were green synthesised using Coriandrum sativum leaf extract. The physicochemical properties of AgNPs were characterised using UV-visible spectrophotometer, field emission scanning microscopy/energy dispersive X-ray (FESEM/EDX), Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Further, in vitro anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised AgNPs were assessed against Propionibacterium acnes MTCC 1951, Malassezia furfur MTCC 1374 and human breast adenocarcinoma (MCF-7) cell line, respectively. The flavonoids present in the plant extract were responsible for the AgNPs synthesis. The green synthesised nanoparticles size was found to be ≈37nm. The BET analysis result shows that the surface area of the synthesised AgNPs was found to be 33.72m(2)g(-1). The minimal inhibitory concentration (MIC) of AgNPs for acne causative agent P. acnes and dandruff causative agent M. furfur was found to be at 3.1 and 25μgmL(-1), respectively. The half maximal inhibitory concentration (IC50) value of the AgNPs for MCF-7 cells was calculated as 30.5μgmL(-1) and complete inhibition was observed at a concentration of 100μgmL(-1). Finally, our results proved that green synthesised AgNPs using C. sativum have great potential in biomedical applications such as anti-acne, anti-dandruff and anti-breast cancer treatment.

Characterization and phylogenetic analysis of antituberculous compound producing actinomycete strain D25 isolated from Thar Desert soil, Rajasthan.

During the course of the anti-infective drug discovery programme, actinomycete strain D25 was recovered from the Thar Desert soil, Rajasthan, India. Actinomycin type of compound isolated from the strain D25 showed promising activity against multi drug resistant and extensively drug resistant M. tuberculosis isolates. The present study reports the characteristics and phylogenetic status of the actinomycete strain D25. Phenotypic and cell wall characteristics revealed that the strain belongs to the genus Streptomyces. Further 16s rRNA analysis confined the genus Streptomyces with 97% similarity to the closely related species Streptomyces althioticus KCTC 9752. The 16s rRNA sequence was submitted to GenBank with the accession number JN604533.1. According to Bossard et al. (2003) strain D25 was found to be a novel species of the genus Streptomyces from Thar Desert soil, Rajasthan.

In vitro antimicrobial and in vivo wound healing effect of actinobacterially synthesised nanoparticles of silver, gold and their alloy

The therapeutic use of metal and alloy nanoparticles is claimed to have reduced side effects and enhanced curative activity as compared to its ionic counterpart. With this view, the present study focused on the synthesis of silver (Ag), gold (Au) and silver/gold (Ag/Au) nanoparticles (NPs) by using actinobacterial metabolites as a reducing agent for enhanced in vitro antimicrobial and in vivo wound healing activities. Physico-chemical parameters of the synthesised nanoparticles were systematically assessed by using X-ray based spectroscopic, zeta potential, dynamic light scattering (DLS), atomic and electron microscopic analysis. The average sizes of the AgNPs, AuNPs and Ag/AuNPs were found to be 30.5 nm, 14.5 nm and 41.5 nm respectively. The synthesized AgNPs and Ag/AuNPs showed better antibacterial activity on Gram negative bacterial pathogens (Escherichia coli, Pseudomonas aeruginosa and Aeromonas hydrophila) than Gram positive bacterial pathogens. A Minimum Inhibitory Concentration (MIC) value of 6.25 μg ml−1 was observed for E. coli, P. aeruginosa and Candida albicans. AgNP and Ag/AuNP based ointments of about 10% concentration heal (100%) the excision wound within 19 and 21 days in contrast with standard ointment. Further, the complete healing process was evaluated by histopathological analysis, and estimation of tensile strength, inflammatory cytokines (IL-6, TNFα, IL-10) and collagen constituents (hexosamine, hydroxyproline and hyaluronic acid). Metal and alloy nanoparticle use may provide a new and effective therapeutic direction for achieving development of novel antimicrobial drugs and scarless wound healing in clinical practice.

Bio-medically active zinc oxide nanoparticles synthesized by using extremophilic actinobacterium, Streptomyces sp. (MA30) and its characterization

Abstract The present study describes the synthesis of zinc oxide nanoparticles (ZnO-NPs) using an extremophilic actinobacterial cell-free extract, supplied with aqueous zinc acetate solution. Crystalline nature, morphological features, and polydispersed nanoparticles size (15–30 nm) were identified by X-ray diffraction (XRD), atomic force and electron microscopic analysis with dynamic light scattering (DLS) study. The interaction between biomolecules and ZnO-NPs was analyzed using Fourier transform infra-red spectroscopy (FT-IR). Furthermore antibacterial, antioxidant activities, and cell viability test of ZnO-NPs were systematically evaluated. The present study opens a new avenue for the actinobacterial synthesis of oxide nanoparticles.

Mechanism of drug resistance, characterization of plasmid-borne determinants and transformation study in P. aeruginosa from burn and ICU units-its susceptibility pattern.

The transfer of drug resistance between hospital pathogens has led to alarming increase of multidrug resistant strains imposing therapeutic challenges. These resistant isolates harbor various mechanisms to counteract the drugs administered and have been reported to deliver these factors to sensitive strains in hostile environment. The present study aimed to screen for multidrug resistant Pseudomonas aeruginosa strains for the production of extended-spectrum β-lactamases, metallo-β-lactamases, AmpC β-lactamase, drug efflux phenotypes and co-transfer the resistance for cephalosporin and other non-beta lactam antibiotics in CaCl2 treated drug sensitive E. coli strains. From the 87 samples processed about 23 isolates of P. aeruginosa were ESBL and MBL positive, 5 (20%) were found to be AmpC β-lactamase producers, efflux mechanism was observed in 8 isolates, 15 isolates had MIC of 16 μg/ml. A putative efflux mechanism was observed in 8 out of 23 isolates that showed decrease in the MIC of meropenem with reserpine. The plasmid profile was characterized for all the common isolates obtained from burn and ICU units. About 69.66% of E. coli recombinants scored positive for both beta lactam and non-beta lactam antibiotics is due to co transfer of resistant plasmid obtained from P. aeruginosa.

Production and optimization of biohydrogen from saccharolytic actinobacterium, Streptomyces rubiginosus (SM16), using sugarcane molasses

ABSTRACT The Actinobacteria are known to produce secondary metabolites like antibiotics, enzymes and pigments and also used in bioremediation. Recently the Actinobacteria have also been reported as a source of biofuels too. Here, the hydrogen production was carried out at different concentrations of sugarcane molasses, pH and temperature through dark H2 fermentation using the actinobacterium Streptomyces rubiginosus (SM16) isolated from a sugarcane molasses dumping site. The maximum biohydrogen production rate was found to be 296 ± 0.042 mL/L at 4% sugarcane molasses. At the optimized pH of 7.0, the maximum biohydrogen production rate was 283 ± 0.015mL/L, whereas at the optimized temperature of 30°C, the yield of biohydrogen was 266 ± 0.022 mL/L using the effective inoculum SM16. The maximum hydrogen production (407.33 ± 5.03 mL/L) was recorded in the optimized fermentation medium with sugarcane molasses 4%, pH 7.0 and temperature 30°C. Gas chromatography (GC) and high performance liquid chromatography (HPLC) analysis proved the presence of organic acid (tartaric acid – 35.7%) and other volatile fatty acids along with H2 gas. Hence, the actinobacterium Streptomyces rubiginosus (SM16) is considered a promising source for biohydrogen production.

Microbial Biodiversity of Selected Major River Basins of India

Indian subcontinent is one of the richest regions in terms of biodiversity. River and its watersheds are the nurseries and habitats for biodiversity, including the microorganisms. In this paper, the biodiversity and ecological significance of four major Indian river basins namely, the Ganges, the Cauvery, the Krishna and the Godavari are reviewed with special emphasis on microorganisms. Through this review we demonstrate that recording and detecting the microbial biodiversity and ecology of river basins would help in the formulation and implementation of appropriate conservation and management strategies in the river ecosystems. It has also shown that, the Ganges river basin is the major microbial diversity region, consisting of nearly 0.5−2.0 × 106 cfu/ml followed by the Cauvery river basin (0.33−2.6 × 105 cfu/ml), Krishna and Godavari basins >0.1−1.0 × 104 cfu/ml.