This study focused on the cellulase production from C. versicolor TD17, white rot fungi. The maximum cellulase activity of 0.897 U/ml was obtained after 5 days of cultivation using 20 g/l cellobiose as a carbon source and 2 g/l ammonium sulfate supplemented with 0.3 g/l urea as nitrogen sources. Enzymatic saccharification of acid-pretreated sweet sorghum straw (SSS) using in house cellulase was optimized using Response Surface Methodology (RSM), variable five-code-level, four-factor; 1.0-7.0% w/v acid-pretreated SSS, 15-35 FPU/g dry substrate of cellulase enzyme, pH 3 to 7 and temperatures 30 to 70 °C. The optimal conditions were 1% w/v acid-pretreated SSS, 25 FPU/g dry substrate of cellulase, pH 5, 50 °C and 72 h cultivation. A maximal glucose yield of 0.440 g/g dry substrate was obtained.

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Genome analysis and optimization of γ-aminobutyric acid (GABA) production by lactic acid bacteria

ABSTRACT

Astaxanthin is a carotenoid pigment extensively used in various industries. Rhodotorula sp. CP72-2, isolated from Calotropis gigantea, showed potential astaxanthin production. In this study, strain CP72-2 was identified as a putative new species in the genus Rhodotorula based on the 26S rRNA gene sequence (98% identity). It was first used as the microbial source for producing astaxanthin. Strain CP72-2 was screened for its astaxanthin production and was identified and quantified by High-Performance Liquid Chromatography (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS), and UV-Vis spectrophotometer. After a screening of astaxanthin production, various carbon sources, pH, temperature, and incubation period were evaluated for their effect on the astaxanthin production of strain CP72-2. Among the several experimental factors, the most efficient conditions for astaxanthin production were glucose (50 g/L), pH 4.5, 25 °C, and three days of cultivation. The assembly genome of strain CP72-2 has a total length of 21,358,924 bp and a GC content of 64.90%. The putative candidate astaxanthin biosynthesis-associated genes (i.e., CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, and CrtZ) were found. This research presents the first report on the production and optimization of astaxanthin from strain CP72-2 and its genome analysis, focusing on the biotechnological potential of the astaxanthin producer.

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