Characterization and Protective Properties of Lactic Acid Bacteria Intended to Be Used in Probiotic Preparation for Honeybees (Apis mellifera L.)—An In Vitro Study

SIMPLE SUMMARY: Honeybees (Apis mellifera L.) are economically and ecologically significant pollinators on a global scale. Various factors such as pathogens, insecticides, viruses, and mites increase colony mortality. The significance of honeybees makes it important to find ecological ways to strengthen the resistance of these insects. Lactic acid bacteria (LAB) are probiotic microorganisms that have a positive effect on the health of the host. Due to numerous beneficial properties, LAB have the potential to improve the viability of honeybees and conditions in apiaries. In this study, we examined the various properties of probiotic candidates such as survival in gastrointestinal conditions and sugar syrups, antibiotics resistance, organic acid profile, cytotoxicity of LAB metabolites, bile salts hydrolase activity, hydrogen peroxide production, β-hemolytic activity, insecticide detoxification by cell-free supernatants, mucin degradation ability and mutual antagonism between isolates. Most of the properties demonstrated by the isolates depended on the tested strain. The obtained results contributed to the selection of LAB to protect honeybees against various health risks. ABSTRACT: Lactic acid bacteria (LAB) are widely used probiotics and offer promising prospects for increasing the viability of honeybees. Thus, the probiotic potential of 10 LAB strains was determined, which in our previous studies showed the most potent protective abilities. In the current study, we investigated various properties of probiotic candidates. The tested LAB strains varied in susceptibility to tested antibiotics. Isolates showed high viability in sugar syrups and gastrointestinal conditions. None of the LAB strains exhibited β-hemolytic activity, mutual antagonism, mucin degradation, hydrogen peroxide production capacity, or bile salt hydrolase (BSH) activity. Additionally, the cytotoxicity of LAB cell-free supernatants (CFS) was assessed, as well as the effect of CFS from P. pentosaceus 14/1 on the cytotoxicity of coumaphos and chlorpyrifos in the Caco-2 cell line. The viability of Caco-2 cells reached up to 89.81% in the presence of the highest concentration of CFS. Furthermore, LAB metabolites decreased the cytotoxicity of insecticides (up to 19.32%) thus demonstrating cytoprotective activity. All tested LAB strains produced lactic, acetic, and malonic acids. This research allowed the selection of the most effective LAB strains, in terms of probiosis, for future in vivo studies aimed at developing an ecologically protective biopreparation for honeybees.