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Biological control agents are a promising substitute for chemical pesticides in agricultural pest management. In this study, Penicillium sp. with high pathogenicity to the agricultural pests oriental leafworm moth (Spodoptera litura) and diamondback moth (Plutella xylostella) were isolated from naturally infected insects and grown on different agricultural residues as an inexpensive substrate for their sporulation. Ten strains of Penicillium (P.01~P.10) were identified as P. citrinum based on morphological features and molecular studies, with sequence analysis using an internal transcribed spacer region. Different fungal isolates exhibited a varying degree of pathogenicity against S. litura and Pl. xylostella, and strains P.04 and P.09 showed the highest pathogenicity to S. litura, with a mortality rate of 92.13% after 7 days of treatments, while strain P.06 resulted in the highest mortality of Pl. xylostella (100%) after 6 days of treatment. Moreover, among ten isolates infected with both S. litura and P. xylostella, P.06 showed potential virulence against S. litura and Pl. xylostella, with lethal time for 50% mortality (LT50) values of 4.5 days and 3.0 days, respectively. The ten isolates showed higher virulence to Pl. xylostella than to S. litura. The agro-industrial-based medium showed efficiency for the cultivation of isolates for sporulation on an industrial scale, suggesting that the newly isolated P. citrinum is a potential biological control agent for controlling insect pests and could be further developed for microbial pesticide production. [ABSTRACT FROM AUTHOR]

Astaxanthin is increasingly attracting commercial interest for its application in the nutraceutical and pharmaceutical industries. This study aimed to produce astaxanthin from molasses with our newly mutated strain of Rhodosporidium toruloides G17 and to evaluate biological activities of the produced astaxanthin. To maximize the astaxanthin yield, the response surface methodology was used so as to optimize the culture conditions. A maximum astaxanthin yield of 1262.08 ± 14.58 µg/L was achieved by growing R. toruloides G17 in a molasses-based medium containing 49.39 g/L reducing sugar, 1.00 g/L urea, 4.15 g/L MgSO4·7H2O, and 10.05% inoculum ratio. The produced astaxanthin was then purified and studied for its antioxidant and anticancer activities. This compound exhibited 123-fold higher antioxidant activity than α-tocopherol, with an IC50 value of 0.97 ± 0.01 µg/mL. The astaxanthin also showed a potent inhibitory ability against the following three cancer cell lines: HeLa, A549, and MCF7, with IC50 values of 69.07 ± 2.4 µg/mL, 55.60 ± 2.64 µg/mL, and 56.38 ± 4.1 µg/mL, respectively. This study indicates that astaxanthin derived from our newly mutated R. toruloides G17 is a promising anticancer and antioxidant agent for further pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Astaxanthin is a valuable carotenoid, which has been approved as a food coloring by the US Food and Drug Administration and is considered as a food dye by the European Union (European Commission). This work aimed to attain Rhodosporidium toruloides mutants for enhanced astaxanthin accumulation using ultraviolet (UV) and gamma irradiation mutagenesis. Gamma irradiation was shown to be more efficient than UV for producing astaxanthin-overproducer. Among the screened mutants, G17, a gamma-induced mutant, exhibited the highest astaxanthin production, which was significantly higher than that of the wild strain. Response surface methodology was then applied to optimize the medium compositions for maximizing astaxanthin production by the mutant G17. The optimal medium compositions for the cultivation of G17 were determined as a peptone concentration of 19.75 g/L, malt extract concentration of 13.56 g/L, and glucose concentration of 19.92 g/L, with the maximum astaxanthin yield of 3021.34 µg/L ± 16.49 µg/L. This study suggests that the R. toruloides mutant (G17) is a potential candidate for astaxanthin production. [ABSTRACT FROM AUTHOR]