一株耐受低pH、高浓度乳酸及琥珀酸菌株的筛选与鉴定

Isolation and identification of a low-pH, lactic acid and succinic acid tolerant strain

摘要:

【目的】通过构建的人工耐酸系统，筛选耐受低pH值、乳酸及琥珀酸的菌株。【方法】构建人工耐酸系统长期驯化菌株，利用不同pH的酸性平板进行筛选，从环境中筛选出一株对低pH值、高浓度乳酸以及琥珀酸有很好耐受性的菌株。通过形态学特征、生理生化特征研究，并结合18S rDNA基因序列分析及分子系统发育树的构建结果，确定菌株的种类。【结果】经过酸性人工系统的长期驯化，筛选分离出一株耐受低pH值，高浓度乳酸以及琥珀酸的菌株WJ-2，经鉴定该菌株为酿酒酵母(Saccharomyces cerevisiae)，其最适生长温度为30 °C。酸性平板实验显示该菌株能够耐受pH 2.5的酸性环境，同时对9%的乳酸及8%的琥珀酸也有很好的耐受性。另外，耐酸菌株WJ-2在pH 2.5、9%乳酸和8%琥珀酸的培养环境中仍能保持相对中性的细胞内pH值。【结论】通过构建人工酸性系统，成功筛选出一株对低pH值、高浓度乳酸以及琥珀酸具有耐受性的菌株——酿酒酵母菌WJ-2，该方法可为筛选具有特定耐受能力菌株提供一个新思路。

Abstract:

[Objective] The aim of this study was to screen a low pH, lactic acid and succinic acid tolerant strain from the artificial acidic ecosystem. [Methods] A strain resistant to low pH, lactic acid and succinic acid was isolated from the artificial acidic ecosystem by acidic plates. We identified the strain by morphological and physiological traits, combined with 18S rDNA gene sequence and phylogenetic trees. [Results] A strain named WJ-2 with low pH, lactic acid and succinic acid tolerance was obtained and identified as Saccharomyces cerevisiae. Its optimal growth temperature was 30 °C, and it could survive in acidic plate at pH 2.5 and grow in the plate with a lactic acid concentration of 9% (w/v). WJ-2 also showed a succinic acid tolerance (8% succinic acid, w/v). WJ-2 also displayed a relative neutral intracellular pH when being challenged at pH 2.5, 9% lactic acid and 8% succinic acid. [Conclusion] Artificial ecosystem is a good alternative to screen strain with specific characteristics.