Identification of Lactobacillus apis A9 Isolated from Honey and Quantitation of its Lead Adsorption
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Abstract:
In an investigation of the probiotic properties of lactic acid bacteria in honey, a gram-positive bacterium was isolated from honey and purified. Based on its colony and cell morphology, physiological and biochemical responses, and 16S rDNA sequencing analysis, the bacterium was identified as Lactobacillus apis A9. This strain was found to be negative for hemolysis, gelatin hydrolysis, nitrate reduction, and amino acid decarboxylation, and susceptible to nine antibiotics, including penicillin. In probiotic experiments the bacterium displayed a high self-aggregation rate (93.37%) and a relatively high hydrophobicity rate (48.71%). It exhibited 43.67% survival after incubation for 3 h at pH 3.0. After 24 h of incubation in solutions of 1 wt.% sodium deoxycholate, 6 wt.% sodium chloride, and 25 wt.% glucose, the survival rates of the bacterium were 96.48%, 68.27%, and 88.57%, respectively. These results indicate that strain A9 possesses strong resistance to acid, bile salts, and hyperosmotic stress. The bacterium displayed a lead (Pb2+) absorption rate of 55.53%. Lead accounted for 5.90% of the bacterium’s surface-displayed elements. Infrared results revealed that hydroxyl and amino groups on the bacterium’s surface interact with lead ions, leading to an increase in α-helices and β-turns in the bacterium’s proteins and a decrease in β-sheets. In summary, L. apis A9 isolated from honey exhibits good safety, probiotic function, and lead adsorption capacity. This study provides new insights into the development and utilization of lactobacilli in honey.
