Enzymatic, antimicrobial, and leishmanicidal bioactivity of gram-negative bacteria strains from the midgut of Lutzomyia evansi, an insect vector of leishmaniasis in Colombia

• Published in: Biotechnology reports (Amsterdam, Netherlands) Vol. 24; p. e00379
• Main Authors: Vivero, Rafael J., Mesa, Gustavo Bedoya, Robledo, Sara M., Herrera, Claudia Ximena Moreno, Cadavid-Restrepo, Gloria
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-12-2019; Elsevier
• Subjects: Antimicrobial screening; Bacteria-intestine interaction; Le. braziliensisenzymatic bioactivity; Leishmanicidal activity; Antimicrobial screening; Bacteria-intestine interaction; Leishmanicidal activity; Le. braziliensisenzymatic bioactivity
• ISSN: 2215-017X; 2215-017X
• DOI: 10.1016/j.btre.2019.e00379

•The methanolic extract of Enterobacter hormaechei showed leishmanicidal activity against promastigotes of Leishmania braziliensis (strain UA301).•P. ananatis, E. cloacae, A. gyllenbergii, O. anthropi and P. otitidis are promising bacteria in the biotechnology field as well as for biological control due to several enzymatic and antimicrobial bioactivities.•Differential production of enzymes and secondary metabolites by Gram-negative bacteria could contribute to physiological and metabolic processes in the intestine of Lutzomyia evansi.
Knowledge regarding new compounds, peptides, and/or secondary metabolites secreted by bacteria isolated from the intestine of phebotominae has the potential to control insect vectors and pathogens (viruses, bacteria, and parasites) transmitted by them. In this respect, twelve Gram-negative bacteria isolated from the intestine of Lutzomyia evansi were selected and screened for their enzymatic, antimicrobial, and leishmanicidal activity. E. cancerogenus, E. aerogenes, P. otitidis, E. cloacae, L. soli, and P. ananatis exhibited enzymatic activity. 83.3% of the isolates displayed lipolytic and nitrate reductase activity and 58.3% of the isolates displayed protease activity. Hemolytic activity (17%) was identified only in E. hormaechei, and P. ananatis. E. cancerogenus, A. calcoaceticus, and P. otitidis showed cellulolytic activity. A. gyllenbergii, P. aeruginosa, and E. hormaechei showed amylolytic activity. In general, the totality of methanolic extracts exhibited antimicrobial activity, where E. hormaechei, A. calcoaceticus, and E. cancerogenus presented the highest activity against the evaluated reference bacteria strains. Cell-free supernatants (CFSS) of the Gram-negative bacteria showed higher growth inhibitory activity against the reference Gram-positive bacteria. The CFS of A. gyllenbergii was the most active antimicrobial in this study, against S. aureus (AAODs = 95.12%) and E. faecalis (AAODs = 86.90%). The inhibition percentages of CFS against Gram-positive bacteria showed statistically significant differences (repeated measure ANOVA df= 2; F= 6.095; P= 0.007832). The E. hormaechei methanolic extract showed leishmanicidal activity (CE-50 μg/ml = 47.7 + 3.8) against metacyclic promastigotes of Leishmania braziliensis (UA301). Based on this finding, we discuss the possible implications of these bacteria in digestion and physiological processes in the Lu. evansi intestine. P. ananatis, E. cloacae, E. hormaechei, and P. otitidis were considered the most promising bacteria in this study and they could potentially be used for biological control.