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Aim: Nano-biotechnologically synthesizing silver nanoparticles via canthaxanthin pigment extracted from Dietzia maris AURCCBT01 and assessing their cytotoxic therapeutic potential against human keratinocyte cell line (HaCaT) were the key objectives of this study., Methods and Results: The pigment extracted from D. maris AURCCBT01 was identified as canthaxanthin using UV-VIS spectroscopy, FTIR, NMR ( 1 H NMR and 13 C NMR) and MS. Canthaxanthin, treated with silver nitrate solution, produced canthaxanthin-mediated silver nanoparticles and they were characterized by UV-VIS spectroscopy, FTIR, XRD, FESEM-EDX and TEM-SAED techniques. UV-VIS spectroscopy pointed out an absorption band at 420 nm, relating to the surface plasmon resonance of silver nanoparticles. FTIR findings suggested that the diverse functional groups of canthaxanthin bio-molecules played a significant task in capping the silver nanoparticles. XRD analysis exhibited 40·20 nm for the crystal size of nanoparticles. FESEM and TEM exhibited that the biosynthesized silver nanoparticles were spherical in shape with crystalline nature and the particle size was 40-50 nm. Moreover, the cytotoxicity assessment of the synthesized nanoparticles in HaCaT revealed significant cytotoxicity in the cultured cells with an IC 50 value of 43 µg ml -1 ., Conclusion: Stable silver nanoparticles synthesized using canthaxanthin from D. maris AURCCBT01 were found effective for application in wound healing activity., Significance and Impact of the Study: Biosynthesized silver nanoparticles via canthaxanthin bacterial pigment exhibited their cytotoxicity effect in HaCaT and testified their eventual therapeutic potential in the wound healing activity with no side effects in a cost effective and eco-friendly process., (© 2020 The Society for Applied Microbiology.)

Marine actinomycetes were isolated from sediment samples collected from Pitchavaram mangrove ecosystem situated along the southeast coast of India. Maximum actinomycete population was noted in rhizosphere region. About 38% of the isolates produced L-asparaginase. One potential strain KUA106 produced higher level of enzyme using tryptone glucose yeast extract medium. Based on the studied phenotypic characteristics, strain KUA106 was identified as Streptomyces parvulus KUA106. The optimization method that combines the Plackett-Burman design, a factorial design and the response surface method, which were used to optimize the medium for the production of L-asparaginase by Streptomycetes parvulus. Four medium factors were screened from eleven medium factors by Plackett-Burman design experiments and subsequent optimization process to find out the optimum values of the selected parameters using central composite design was performed. Asparagine, tryptone, d) extrose and NaCl components were found to be the best medium for the L-asparaginase production. The combined optimization method described here is the effective method for screening medium factors as well as determining their optimum level for the production of L-asparaginase by Streptomycetes parvulus KUAP106.