Antimicrobial activity of the pygidial gland secretion of the troglophilic ground beetleLaemostenus(Pristonychus)punctatus(Dejean, 1828) (Insecta: Coleoptera: Carabidae)

Abstract

The antimicrobial activity of the pygidial gland secretion released by adult individuals of the troglophilic ground beetle Laemostenus (Pristonychus) punctatus (Dejean, 1828), applying microdilution method with the aim to detect minimal inhibitory concentration, minimal bactericidal concentration and minimal fungicidal concentration, has been investigated. In addition, morphology of the pygidial glands is observed. We have tested 16 laboratory and clinical strains of human pathogens - eight bacterial both gram-positive and gram-negative species and eight fungal species. The pygidial secretion samples have showed antimicrobial properties against all strains of treated bacteria and fungi. Micrococcus flavus proved to be more resistant compared with other bacterial strains. More significant antimicrobial properties of the secretion are observed against Escherichia coli, which proved to be the most sensitive bacteria. Aspergillus fumigatus proved to be the most resistant, while Penicillium ochrochloron and Penicillium verrucosum var. cyclopium the most sensitive micromycetes. Commercial antibiotics Streptomycin and Ampicillin and antimycotics Ketoconazole and Bifonazole, applied as positive controls, showed higher antibacterial properties for all bacterial and fungal strains, except for P. ochrochloron, which proved to be more resistant on Ketoconazole compared with the pygidial gland secretion of L. (P.) punctatus. Apart from the role in ecological aspects, the antimicrobial properties of the tested secretion possibly might have medical significance in the future.

The pygidial gland secretion of Laemostenus punctatus (Coleoptera, Carabidae): a source of natural agents with antimicrobial, anti-adhesive, and anti-invasive activities

“…In previous studies, it was assumed that the antimicrobial activity of the secretion of L. (P.) punctatus is probably caused by the interaction of several chemical components acting synergistically (Nenadić et al, 2016b;Nenadić, 2019), but in this study we found that the selected fatty acids from the secretion were indifferent in combination as formic acid achieved much stronger antimicrobial activity compared to oleic acid. 10.3389/fevo.2023.1148309 In this study, the beta-lactam antibiotics ampicillin and cephalexin and the aminoglycoside streptomycin were found to have weaker antibacterial activity than the tested secretion and formic acid.…”

“…10.3389/fevo.2023.1148309 In this study, the beta-lactam antibiotics ampicillin and cephalexin and the aminoglycoside streptomycin were found to have weaker antibacterial activity than the tested secretion and formic acid. In contrast, Nenadić et al (2016b) noted that the commercial antibiotics streptomycin and ampicillin and the antifungal agents ketoconazole and bifonazole generally exhibited higher antimicrobial potential against all tested bacterial and fungal strains, with the exception of Penicillium ochrochloron, which was found to be more resistant to ketoconazole and more sensitive to the pygidial gland secretion of L. (P.) punctatus (MIC 1.1 mg/mL, MBC 2.2 mg/mL). Interestingly, the secretion displayed a higher antibacterial potential against the non-resistant E. coli, P. aeruginosa, and S. aureus strains in the current study, with MIC values about 100 times lower.…”

“…The antimicrobial activity of the secretions of representatives of the ground beetle subfamily Platyninae was initially investigated by Nenadić et al (2016b), who presented the first in vitro antimicrobial screening of the pygidial gland secretion of L. (P.) punctatus against various human microbial pathogens, including clinical and laboratory strains. Although undecane and dodecyl acetate were found in its secretion mixture in the highest percentage (Vesović et al, 2015), their possible antimicrobial properties have not been reported in the literature.…”

“…Palmitic and stearic acids also exhibit antibacterial activity against both gram-positive and gram-negative bacteria (Casillas-Vargas et al, 2021). The production of formic acid as a defensive chemical is widespread in different ground beetles (Francke and Dettner, 2005;Lečić et al, 2014;Nenadić et al, 2016b). It is wellknown that formic acid has been added to poultry diets to limit Salmonella spp.…”

“…and other foodborne pathogens in the feed and potentially in the gastrointestinal tract (Gómez-García et al, 2019;Ricke et al, 2020). Nenadić et al (2016b) gave the very first data on the antimicrobial potential of the pygidial gland secretion of L. (P.) punctatus against various human pathogens (clinical and laboratory gram-negative and gram-positive bacterial strains and fungal species), while Dimkić et al (2020) analyzed the antimicrobial activity of this secretion against guano-dwelling bacterial and fungal strains. Prior to these studies, taxa within the ground beetle subfamily Platyninae were generally poorly known in this regard.…”