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H2O2 production in Lactobacillus strains isolated from the intestinal microbiome of healthy people

Lactobacillus sp. in the digestive tract are capable of producing H2O2 to inhibit the growth of harmful bacteria and balance the gut microflora. In this study, we have isolated 115 strains of Lactobacillus spp. from stool samples of healthy people in Ha Noi. | TAP CHI SINH HOC 2020 42 1 83 92 DOI 10.15625 0866-7160 v42n1.14508 H2O2 PRODUCTION IN Lactobacillus STRAINS ISOLATED FROM THE INTESTINAL MICROBIOME OF HEALTHY PEOPLE Ha Thi Thu1 Hoang The Hung2 Tran Xuan Thach1 Nguyen Thi Hoa1 La Thi Lan Anh3 Vu Thi Hien1 Nguyen Dinh Duy1 Dong Van Quyen1 Nguyen Thi Tuyet Nhung1 1 Molecular Microbiology Department - Institute of Biotechnology IBT - Vietnam Academy of Science and Technology VAST 2 Research Institute of Military Logistics Science - Military Academy of Logistics 3 Graduate University of Science and Technology - VAST Received 20 October 2019 accepted 6 January 2020 ABSTRACT Lactobacillus sp. in the digestive tract are capable of producing H 2O2 to inhibit the growth of harmful bacteria and balance the gut microflora. In this study we have isolated 115 strains of Lactobacillus spp. from stool samples of healthy people in Ha Noi. Of the 50 tested Lactobacillus strains 9 strains were capable of producing H 2O2 of which the Lac.VFE-14 strain produced highly H2O2 with a concentration of 2.183 mM followed by Lac.VFE-08 strains 2.081 mM and Lac.VFE-04 2.067 mM . All three strains grew well in MRS medium supplemented with bile salts or adjusted to low pH value. With 0.3 of bile salt the survival rates of these 3 strains were 99 95 and 97 respectively. At pH 3.0 after 3 hours of cultivation the survival rates of the three strains were 98.54 94.15 and 95.27 respectively. In addition each of the cell-free culture supernatants of these three strains that inhibit the growth of S. aureus ATCC-23235. The inhibition zone diameters of the three strains were 19.0 1.0 mm 14.0 1.0 mm and 11.7 1.3 mm respectively. The results of 16S rRNA gene analyses showed that Lac.VFE-14 Lac.VFE-08 and Lac.VFE-04 had high similarity scores with L. plantarum ZZU 23 100 L. rhamnosus JCM 1136 99 and L. plantarum S7 98.65 respectively. This study indicates that all three strains have the potential to be used as probiotics in the future. Keywords .