2 and 16

The biogenic entities are found to secrete large amount of proteins which are found to be responsible for metal ion reduction and morphology control.17 In different microorganisms, various enzymes are believed to take part in the bioreduction process involving the transport of electrons from certain electron donors to metal electron acceptors. Some studies of non-enzymatic reduction mechanism suggested that some organic functional groups of microbial cell walls could be responsible for the bioreduction process.18 All the above mechanisms Wnt antagonist could result in the intracellular or extracellular complexation and the deposition of metal nanoparticles. Biogenic nanoparticles are toward a greener approach and environment friendly with no toxic hazardous chemical employed in synthesis protocol with synthesis process taking place at ambient temperature and pressure conditions.19, 20 and 21 Mean while marine microorganisms are reported to reduce the metallic ions and convert them into phosphates, sulfides, carbonates, and/or intracellularly sequester PD0325901 ic50 them with low molecular weight such as cysteine rich proteins glutathione or phytochelatins which are induced upon

exposure to metals in biological system.22, 23, 24, 25 and 26 The metal peptide interaction is another incentive to use the biosynthetic route for nanoparticle synthesis as capping of metal nanoparticles by peptides such as phytochelatins prevents aggregation into bulk crystals, thus yielding stable nanoparticles.27 The variable biodiversity in the marine environment with that of the terrestrial environment influence researchers to exploit marine flora in array of applications, the interference between marine microbial systems and nanotechnology has opened a new avenue by employing marine microorganism in synthesis of nanoparticles.

Based on the literature pursued it is reported that when two isolates of marine actinomycetes i.e., Streoptomyces parvulus SSNP11 ADP ribosylation factor and Streptomyces albidoflavus CNP10 challenged with silver inhibitors nitrate and incubate at 30 °C .The bioreduction of the silver ions was associated with metabolic processes utilizing nitrate by reducing nitrate to nitrite and ammonium. The produced silver nanoparticles exhibited maximum absorbance at 400–410 nm in UV–Vis spectroscopy. The reaction products were analyzed using transmission electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The study also reported that the production of silver nanoparticles was both intra and extracellular. The report also suggested that exposure to varying temperature, pH and substrate concentration influences, directly or indirectly, the rate of nanoparticles fabrication. 28 Similarly six fungal strains were isolated from marine mangrove sediment from Parangipettai.