Lichen-Associated Endophytes from Helan Mountains: Insight into Microbial Diversity and Application.

Area of Science:

• Microbiology
• Natural Products Chemistry
• Biotechnology

Background:

• Endophytic bacteria residing in lichens produce secondary metabolites with diverse bioactivities.
• These metabolites possess potential therapeutic applications, including antibacterial, anti-inflammatory, and anti-tumor properties.

Purpose of the Study:

• To isolate and identify endophytic bacterial strains from lichens in the Helan Mountains.
• To evaluate the antibacterial activity and environmental adaptability (salt and alkali tolerance) of these isolated strains.

Main Methods:

• Isolation and morphological identification of 17 distinct endophytic bacterial strains from lichens.
• Antibacterial activity assays against *Staphylococcus aureus*, *Proteus vulgaris*, and *Candida albicans*.
• Salt and alkali tolerance tests at various NaCl concentrations and pH levels.

Main Results:

• The isolated strains comprised 13 *Streptomyces*, 1 *Niallia*, 1 *Acinetobacter*, 1 *Peribacillus*, and 1 *Pseudarthrobacter*.
• Secondary metabolites from 14 strains inhibited *S. aureus*, 8 inhibited *P. vulgaris*, and 6 inhibited *C. albicans*.
• Three strains demonstrated salt tolerance up to 100 g/l NaCl, and 14 strains showed alkali tolerance up to pH 11.

Conclusions:

• Endophytic bacteria from Helan Mountain lichens exhibit significant antibacterial potential.
• These strains display remarkable adaptability to high salt and alkali conditions.
• The findings provide a basis for further research into novel bioactive compounds from these extremophilic endophytes.