Ma Xin, Lv Jiaxuan, Ma Xiangrong, Zhu Derui, Long Qifu, Xing Jiangwa
Department of Basic Medical Sciences, Qinghai University Medical College, Xining 810016, China.
J Appl Microbiol. 2025 Jan 6;136(1). doi: 10.1093/jambio/lxaf002.
The aim of this study is to increase the diversity of culturable halophilic archaea by comparing various isolation conditions and to explore the application of halophilic archaea for enzyme-producing activities and antimicrobial properties.
We systematically compared the isolation performance of various archaeal and bacterial media by isolating halophilic archaea from the Da Qaidam Salt Lake, a magnesium sulfate subtype hypersaline lake on the Qinghai-Tibet Plateau, China, using multiple enrichment culture and gradient dilution conditions. A total of 490 strains of halophilic archaea were isolated, which belonged to five families and 11 genera within the order Halobacteriales of the class Halobacteria of the phylum Euryarchaeota. The 11 genera consisted of nine known genera and two potentially new genera, the former including Halorubrum, Natranaeroarchaeum, Haloplanus, Haloarcula, Halorhabdus, Halomicrobium, Halobacterium, Natrinema, and Haloterrigene. Halorubrum was the dominant genus with a relative abundance of 78.98%. By comparing different culture conditions, we found that bacterial media 2216E and R2A showed much better isolation performance than all archaeal media, and enrichment culture after 60 d and dilution gradients of 10-1 and 10-2 were best fitted for halophilic archaea cultivation. The screening of 40 halophilic archaeal strains of different species indicated that these halophilic archaea had great extracellular enzyme activities, including amylase (62.5%), esterase (50.0%), protease (27.5%), and cellulase (15.0%), and possessed great antimicrobial activities against human pathogens. A total of 34 strains exhibited antimicrobial activity against four or more pathogens, and 19 strains exhibited antimicrobial activity against all six pathogens.
The diversity of culturable halophilic archaea was significantly increased by enrichment culture and selection of bacterial media, and screening of representative strains showed that halophilic archaea have multiple extracellular enzyme activities and broad-spectrum antimicrobial activity against human pathogens.
本研究旨在通过比较不同的分离条件来增加可培养嗜盐古菌的多样性，并探索嗜盐古菌在产酶活性和抗菌特性方面的应用。
我们通过多次富集培养和梯度稀释条件，从中国青藏高原的硫酸镁亚型盐湖——大柴旦盐湖中分离嗜盐古菌，系统地比较了各种古菌和细菌培养基的分离性能。共分离出490株嗜盐古菌，它们属于广古菌门盐杆菌纲盐杆菌目下的5个科和11个属。这11个属包括9个已知属和2个潜在新属，前者包括嗜盐碱红菌属、嗜盐嗜碱厌氧古菌属、嗜盐平面菌属、嗜盐弧菌属、嗜盐栖芽孢杆菌属、嗜盐微菌属、嗜盐杆菌属、嗜盐嗜碱球菌属、嗜盐陆生菌属。嗜盐碱红菌属是优势属，相对丰度为78.98%。通过比较不同培养条件，我们发现细菌培养基2216E和R2A的分离性能比所有古菌培养基都要好，60天的富集培养以及10-1和10-2的稀释梯度最适合嗜盐古菌培养。对40株不同种的嗜盐古菌进行筛选表明，这些嗜盐古菌具有很强的胞外酶活性，包括淀粉酶（62.5%）、酯酶（50.0%）、蛋白酶（27.5%）和纤维素酶（15.0%），并且对人类病原体具有很强的抗菌活性。共有34株菌株对四种或更多病原体表现出抗菌活性，19株菌株对所有六种病原体都表现出抗菌活性。
通过富集培养和选择细菌培养基，可培养嗜盐古菌的多样性显著增加，对代表性菌株的筛选表明嗜盐古菌具有多种胞外酶活性以及对人类病原体的广谱抗菌活性。
