摘要
[目的]从含盐环境中富集分离中度嗜盐菌,并进行菌种鉴定,分析确定与耐盐特性相关的主要相容性溶质,探索利用分离菌株合成四氢嘧啶的可行性。[方法]从盐池土中富集分离耐盐或嗜盐的乙酸降解菌,通过生理生化特性测定和16S rDNA序列的分析,将所得菌株鉴定至相应的属或种。通过摇瓶试验研究分离菌株耐盐生长的特征,从所得的菌株中提取、分析相容性溶质并测量其含量,初步分析分离菌株耐盐生长的机制。在高盐培养基中诱导嗜盐菌胞内相容性溶质的合成,然后在低渗盐溶液中测定相容性溶质的释放率,之后再将菌体转移至高渗培养基中研究相容性溶质重新合成的效率。[结果]从盐池土中成功分离到一株中度嗜盐菌W2,根据生理生化特性和16S rDNA序列比对结果,菌株W2属于Halomonas属,其16S rDNA序列与Halomonas ventosae Al12~T(AY268080)的相似性最高(99.93%)。菌株W2可耐受的NaCl质量浓度范围为25~200 g·L^(-1),其最适生长所需的NaCl质量浓度为100 g·L^(-1)。在高盐培养基中菌株W2单位质量细胞合成的四氢嘧啶产率达161 mg·g^(-1),占胞内4种相容性溶质总量的70.8%。低渗条件下导致W2菌体内四氢嘧啶释放的最适盐质量浓度为30 g·L^(-1),低渗冲击5 min以后释放率达61.2%,而转入高渗培养基中培养3 h后即可重新合成。[结论]Halomonas sp.W2是一株以四氢嘧啶为主要相容性溶质的中度嗜盐菌,该菌四氢嘧啶的产率较高,而且具有高渗合成、低渗释放的功能,因而在四氢嘧啶的生物合成中具有较好的应用潜力。
[ Objectives ] The present study was aimed to isolate and identify moderately halophilic bacterium from saline environment, characterize major compatible solutes and explore the feasibility of producing ectoine by using the isolated strain. [ Methods] Halotolerant or halophilic acetic acid-degrading bacteria were enriched and isolated from saltern sediment. Physicochemical properties were determined and bacterial identification was accomplished through analysis of physicochemical tests and 16S rDNA sequence similarity. Shake-flask experiments were carried out to investigate the effects of salinity on the growth of the isolate. Intracellular compatible solutes were extracted and quantified with the purpose of analyzing the mechanism for halophilic growth of the isolate. The isolate was first cultured in high salinity medium to induce the synthesis of intracellular compatible and then release rate of intracellular compatible was investigated by transferring the cells to low salinity medium. After osmotic downshock re-synthesis was determined by further transferring the isolate back to fresh medium with high salinity. [ Results ] A moderately halophilic bacterium W2 was isolated from saltern sediment and identified as a member of the genus Halomonas according to its physiological properties and 16S rDNA sequence analysis. The most closely related species was Halomonas ventosae Al12 T（AY268080） with the 16S rDNA sequence similarity 99.93%. Strain W2 could tolerate a broad range of salinity from 25 to 200 g·L-1 of NaCl. Optimal growth was observed in the acetate medium containing 100 g·L-1 NaCl. In high salinity medium strain W2 accumulated ectoine as its major compatible solute at a yield of 161 mg·g-1 ,which accounted for 70.8% of the total of four intracellular compatible solutes. Optimal salinity required for efficient ectoine release under hypo-osmotic stress was 30 g·L-1 ,which may result in a release rate of 61.2% of intracellular ectoine. Furthermore intracellular ectoine could be re-synthesized three
出处
《南京农业大学学报》
CAS
CSCD
北大核心
2017年第1期109-115,共7页
Journal of Nanjing Agricultural University
基金
国际科学基金项目(W4260-1)
关键词
中度嗜盐菌
四氢嘧啶
细菌泌乳
高渗-低渗冲击
moderately halophilic bacterium
ectoine
bacterial milking
hyper/hypo-osmotic shock
