Exploring halo enzymes and halo biosurfactants production from halophilic and halotolerant bacteria isolated from Lake Qarun solar salterns

Abstract Halophilic and halotolerant bacteria are microorganisms that thrive in hypersaline environments. They have much potential in several fields in life, such as Industry and agriculture. In this study, five isolates were obtained from four saline ponds of Qarun Lake using Nutrient Agar (NA) medium prepared with water from the ponds. Among them, QSLA17 was considered a halotolerant bacterium, while QSLA1, QSLA7, QSLA14, and QSLA16 were considered halophilic bacteria. The 16S rRNA analysis demonstrated that the isolates were affiliated with three groups: Firmicutes, Gammaproteobacteria, and Alphaproteobacteria. The ability of isolates to produce hydrolytic enzymes and biosurfactants was tested. After initial screening, all isolates were found to have positive lipase activity using Tween 80 as a substrate, while QSLA1 and QSLA7 isolates were able to produce lipase using olive oil. QSLA14, QSLA16, and QSLA17 isolates demonstrated the ability for esterase production, while QSLA1, QSLA7, and QSLA14 isolates succeeded in producing casease. Gelatinase (protease) was excreted by isolates QSLA1, QSLA7, QSLA14, and QSLA17, while chitinase was produced by isolates QSLA1, QSLA7, QSLA14, and QSLA16. Moreover, all isolates demonstrated their ability to produce biosurfactants while growing in Modified Landy Medium with different salt concentrations, and in this context, the QSLA1 isolate demonstrated the best results compared to the other isolates.