Detection of Lactic Acid Bacteria in Metasandstone and Limestone Caves of Chapada Diamantina, Brazil

Caves are unique habitats, ranging from well-illuminated to devoid of light environments that host various forms of life. Among the microbial groups that can inhabit these environments across different lithologies are lactic acid bacteria (LAB), a widely distributed group of bacteria that are poorly understood in cave environments. In this study, samples from limestone and sandstone caves were analyzed to determine the presence of LAB using two group-specific primer pairs. Only one of the primer pairs amplified, and the DGGE analysis showed a profile with a few bands for each sample, except for the entrance and the first inner sample from the metasandstone cave, and one inner sample from the limestone cave, which had a higher number of operational taxonomic units (OTUs). Sequencing of selected OTUs revealed the presence of Streptococcus and Lactococcus. Energy-dispersive X-ray spectroscopy showed that the inner sample from the limestone cave with a higher number of OTUs also had a higher percentage of magnesium. Despite efforts to cultivate LAB using common culture media such as MRS and GYP, no growth was observed, suggesting that these media may not be suitable for isolating LAB from cave sediments and rocks. The presence of this group in all nine samples analyzed from caves highlights the significance of these microorganisms and suggests the need for further research to cultivate and understand their role in the cave microbial community and their biotechnological potential.

The online version contains supplementary material available at 10.1007/s12088-024-01270-1.