In Vitro Antagonistic Effect of Gut Bacteriota Isolated from Indigenous Honey Bees and Essential Oils against Paenibacillus Larvae

Abstract

The aim of study was to isolate and identify the gut bacteria of Apis mellifera and to evaluate antagonistic effect of the bacteriota against Paenibacillus larvae, which causes American foulbrood (AFB) in honeybees. The dilution plating method was used for the quantification of selected microbial groups from digestive tract of bees, with an emphasis on the bacteriota of the bees’ intestines. Bacteria were identified using mass spectrometry (MALDI-TOF-MS Biotyper). Overall, five classes, 27 genera and 66 species of bacteria were identified. Genera Lactobacillus (10 species) and Bacillus (8 species) were the most abundant. Gram-negative bacteria were represented with 16 genera, whereas Gram-positive with 10 genera. Delftia acidovorans and Escherichia coli were the most abundant in the digestive tract of honey bee. Resistance to a selection of antimicrobials was assessed for the bacterial isolates from bee gut and confirmed against all antimicrobials included in the study, with the exception of cefepime. Lactobacillus spp., especially L. kunkeei, L. crispatus and L. acidophilus. showed the strongest antimicrobial activity against P. larvae, the causal pathogen of AFB. Antimicrobial activity of essential oils against isolated bacteria and two isolates of P. larvae were assessed. Application of a broad selection of plant essential oils indicated that Thymus vulgaris had the highest antimicrobial activity against P. larvae.

Antagonistic Activity of Bacteria Isolated from the Periplaneta americana L. Gut against Some Multidrug-Resistant Human Pathogens

“…Even insects that inhabit unpolluted environments (e.g., bees and wasps) have a gut microflora that has antagonistic effects against pathogens [ 47 ]. Miroslava et al 2020 isolated and identified the gut bacteria of Apis mellifera and evaluated its antagonistic effect against Paenibacillus larvae, which causes American foulbrood (AFB) in honeybees [ 48 ]. The results of Guzman and Vilcinskas [ 15 ] revealed that the gut bacteria of cockroaches produce active molecule(s) with potent antibacterial properties.…”

Characterization of Apis mellifera Gastrointestinal Microbiota and Lactic Acid Bacteria for Honeybee Protection—A Review

“…bacteria added to sugar syrup at 10 5 CFU/mL concentration. L. kunkeei , Lactobacillus crispatus, and L. acidophilus showed the strongest antagonistic activity against a highly virulent bacterium, P. larvae [ 195 ]. In one study, honeybee larvae and adult bees were administered a mixture of four different strains of L. kunkeei.…”

Biologically Active Extracts from Different Medicinal Plants Tested as Potential Additives against Bee Pathogens

“…In several studies, essential oils of mint, melissa, coriander and thyme [ 38 ]; other phytochemicals, including caffeine, clove oil, gallic acid, kaempferol and p -coumaric acid; and even propolis showed effective antimicrobial activity, expanded honey bee longevity and, to some extent, reduced nosemosis levels [ 37 , 39 , 40 , 41 , 42 ]. Other natural products tested as additives in honey bee feeding, such as BioPatty, which contains a mixture of Lactobacillus plantarum Lp39, Lactobacillus rhamnosus GR-1 and Lactobacillus kunkeei BR-1, could reduce pathogen loads, up-regulate the expression of key immune genes and improve survival during P. larvae infection [ 43 , 44 , 45 ]. Hydroalcoholic laurel extract [ 12 ], Cinnamomum zeylanicum, Syzygium aromaticum , propolis and Thymus vulgaris are active against M. plutonius [ 46 ].…”