Discovery of Phloeophagus Beetles as a Source of Strains That Produce Potentially New Bioactive Substances and Description of sp. nov.

Antimicrobial resistance is a worldwide problem that threatens the effectiveness of treatments for microbial infection. Consequently, it is essential to study unexplored niches that can serve for the isolation of new microbial strains able to produce antimicrobial compounds to develop new drugs. Bark beetles live in phloem of host trees and establish symbioses with microorganisms that provide them with nutrients. In addition, some of their associated bacteria play a role in the beetle protection by producing substances that inhibit antagonists. In this study the capacity of several bacterial strains, isolated from the bark beetles , and , to produce antimicrobial compounds was analyzed. Several isolates exhibited the capacity to inhibit Gram-positive and Gram-negative bacteria, as well as fungi. The genome sequence analysis of three isolates predicted the presence of several gene clusters implicated in the production of already described antimicrobials and moreover, the low similarity of some of these clusters with those previously described, suggests that they encode new undescribed substances, which may be useful for developing new antimicrobial agents. Moreover, these bacteria appear to have genetic machinery for producing antitumoral and antiviral substances. Finally, the strain IA19 showed to represent a new species of the genus . The 16S rRNA gene sequence analysis showed that its most closely related species include and 98.6, 98.5 98.4, and 98.4% identity, respectively. MLSA of the housekeeping genes B, B, and D confirmed that strain IA19 clearly separates from its closest related species. Average nucleotide identity between strains IA19 and ATCC 700689, DSM 11363, KL28 and DSM 17257 were 85.3, 80.2, 79.0, and 72.1%, respectively. Growth occurs at 4-37°C and pH 6.5-8. Optimal growth occurs at 28°C, pH 7-8 and up to 2.5% NaCl. Respiratory ubiquinones are Q9 (97%) and Q8 (3%). C16:0 and in summed feature 3 are the main fatty acids. Based on genotypic, phenotypic and chemotaxonomic characteristics, the description of sp. nov. has been proposed. The type strain is IA19 (=CECT 9403 = LMG 30182).