高糖胁迫对小球藻生长和类胡萝卜素合成的影响OA

[Objective]This study aimed to alleviate the inhibitory effect of high initial glucose concentration on the growth and carotenoid synthesis of Chlorella vulgaris during fermentation.[Methods]High glucose-tolerant C.vulgaris strains were screened with biomass and carotenoid yield as indicators,using UV mutagenesis combined with directional domestication under glucose concentration gradient stress.The mechanism underlying the effect of high glucose stress on the growth of C.vulgaris was analyzed at the transcriptome level,and the result were verified by RT-qPCR.[Results]A C.vulgaris strain capable of tolerating a glucose concentration of 30 g/L was obtained through directional domestication.Compared with the original strain,its glucose tolerance increased by approximately 50%,and the carotenoid yield reached 5.38 mg/L.The FPKM density distribution of gene expression in the high glucose-tolerant strain differed significantly from that of the control group,and the two expression patterns showed low similarity.Four upregulated differentially expressed genes(DEGs)related to the cysteine and methionine metabolism pathway in the high glucose-tolerant strain led to the accumulation of propionate and its derivatives in cells,thereby inhibiting growth.The expression levels of gene 2.1.1.14,gene 2.5.1.6,and gene 3.5.99.7 were upregulated 184.74-fold,175.68-fold,and 179.28-fold,respectively,compared with the control group.[Conclusion]The strategy of UV mutagenesis combined with directional domestication under glucose concentration gradient stress can effectively improve the glucose tolerance of C.vulgaris,and the abnormal regulation of the cysteine/methionine metabolism pathway is one of the important molecular mechanisms by which high glucose stress inhibits its growth.