Midgut health of Apis mellifera workers on oral administration of Lactobacillus rhamnosus and organic acids

Abstract

A study about the provision of Lactobacillus rhamnosus NR_113332) and organic acids was carried out. 108 colony-forming units of probiotics were provided to the caged workers with and without the addition of 2.99% lactic acid, 2.91% acetic acid, and 1.96% acetic acid. After two weeks of oral administration, on termination, five bees were collected and dissected from each cage, and their midguts were cut into 8 μm thick sections by microtome. Subsequently, these histologically processed preparations were observed under camera fitted microscope. It was observed that the experimental workers were provided with diets: (pollen+ 50% w/v sucrose in 1.96% acetic acid, pollen+ L. rhamnosus in 50% w/v sucrose in distilled water, pollen+ L. rhamnosus in 50% w/v sucrose in 2.99% lactic acid, pollen+ L. rhamnosus in 50% w/v sucrose in 2.91% acetic acid, pollen+ L. rhamnosus in 50% w/v sucrose in 1.96% acetic acid) had a considerable quantity of peritrophic membranes. The mean midgut lumen diameters (µm2) were 373.33 ± 98.38, 296.67 ± 23.33, 243.33 ± 71.72, 426.67 ± 40.55, 576.67 ± 93.87 as compared to control’s 240.00 ± 30.55. The provision of probiotic and organic acids resulted in a slightly disturbed midgut epithelial wall, the presence of more quantity of peritrophic membranes, saved regeneration crypts, more gastric cells discharging, and some cytoplasmic vacuolization of caged worker bees. Our study suggests that probiotics and organic acids can be used as an environmentally friendly apipromotor, but verification by field studies is needed.