Isolation optimization and screening of halophilic enzymes and antimicrobial activities of halophilic archaea from the high-altitude, hypersaline Da Qaidam Salt Lake, China.

This article focuses on increasing the diversity of culturable halophilic archaea from the Da Qaidam Salt Lake, a magnesium sulfate subtype hypersaline lake on the Qinghai-Tibet Plateau, China, by comparing various isolation conditions and assessing their enzyme-producing and antimicrobial activities. A total of 490 halophilic archaeal strains were isolated, representing five families and 11 genera within the order Halobacteriales, including two potentially new genera; the genus Halorubrum was dominant. The study found that bacterial media 2216E and R2A outperformed traditional archaeal media in isolating diverse halophilic archaea, with enrichment culture periods of up to 60 days and dilution gradients of 10⁻¹ and 10⁻² being optimal. Screening of 40 representative strains revealed high extracellular enzyme activities (amylase, esterase, protease, cellulase) and broad-spectrum antimicrobial effects against common human pathogens, highlighting their potential for industrial enzyme production and antimicrobial drug development.