[Isolation, identification and naringin biotransforming properties of naringinase producing bacteria isolated from...

Isolation of specific bacteria from human intestinal microflora to convert naringin to naringenin efficiently.

Fresh human feces from healthy individual was cultured in an anaerobic chamber for 24 h before being diluted and spread on agar medium. We cultured and incubated each single colony with the substrate naringin. The biotransformation of naringin by each single colony was detected by high-performance liquid chromatography (HPLC). We identified the isolated bacteria based on the analyses of 16S rDNA sequence and biochemical traits. We also studied the bioconversion kinetics of the bacteria.

Four bacterial strains, named AUH-JLD3, AUH-JLD7, AUH-JLD104 and AUH-JLD109, capable of biotransforming naringin to naringenin, were isolated and identified as Blautia sp. AUH-JLD3, Enterococcus sp. AUH-JLD7, Bacteroides sp. AUH-JLD104 and Streptococcus pasteurianus subsp. AUH-JLD109 respectively based on the 16S rDNA sequence analysis, bacterial cell morphology, and biochemical traits. Study on biotransforming kinetics showed that all the four isolated bacterial strains were able to convert naringin (0.2 mmol/L) to naringenin within 12 h. The maximal concentration of the substrate naringin that strain AUH-JLD3, strain AUH-JLD7, strain AUH-JLD104 and strain AUH-JLD109 could biotransform efficiently were 0. 2 mmol/L (the average biotransforming rate was 66. 67%), 0.8 mmol/L (the average biotransforming rate was 86.49%), 0. 2 mmol/L (the average biotransforming rate was 73.68%) and 1.6 mmol/L (the average biotransforming rate was 93.20%), respectively.

The four bacterial strains were capable of biotransforming naringin to naringenin, among which Streptococcus pasteurianus subsp. AUH-JLD109 has the highest naringin biotransforming capacity.