乳酸菌抗诱变致癌物质研究

Study on lactic acid bacteria on inhibiting mutagenic and carcinogenic substances

不少对健康有害的物质,如苯酚、甲苯酚、吲哚、次级胆汁酸和雌性激素等在体内长期积累会诱发结肠癌的发生。本文考察了戊糖乳杆菌Ind1和Ind3清除苯酚、对甲酚和吲哚这些诱变物质的能力,结果显示:只有浓度大于150μg/mL的苯酚、对甲酚和吲哚对菌株生长显示略有影响,影响与物质及其浓度和菌株有关,但是经37℃厌氧培养144h后,三个菌株的活菌数仍然在106cfu/mL以上,说明戊糖乳杆菌对肠道中有害的酚类物质有较高的耐受性。在浓度为5μg/mL以及50μg/mL的苯酚和对甲酚培养基中,戊糖乳杆菌Ind1和Ind3在37℃分别培养24h和144h后,苯酚和对甲酚含量明显被减少,其浓度在0·95～1·93μg/mL之间,对甲酚浓度在0·45～1·14μg/mL之间,3株乳杆菌活菌数从109cfu/mL降至106cfu/mL,诱变因子的吸附量随着细胞培养时间的延长而降低,表明乳杆菌细胞对突变因子有较好的黏附或降解作用。

Some intestinal bacteria can produce many genotoxic, mutagenic and carcinogenic substances. The major products of the bacterial aromatic amino acids fermentation-phenolic and indolic compounds which are responsible for colon cancer development are accumulated in the colon. The ability of Lactobacillus pentosus strains Ind1 and Ind3 on tolerant and reducing the amount of phenol, p-cresol and indole potentially existing in the intestinal tract was investigated. Result shows that only concentration higher than 150μg/mL showed slightly inhibition against the bacterial growth.Although the impact on growth and survival of strain by precarcinogenics are varied between different substance at various concentration and strain independent, the viability of the tested lactobacilli strains were all above 106cfu/mL after 144h-incubation at 37℃.After incubating at 37℃ for 24hours and 144hours at the medium containing phenol and p-cresol, L.pentosus strains Ind1 and Ind3 reduced the amount of the phenol from 51μg/mL to 0.95μg/mL after 24h and 1.93μg/mL after 144h, respectively.The amount of p-cresol was decreased from 5μg/mL to 1.14μg/mL after 24h-incubation and to 0.45μg/mL after 144h. Meanwhile, the cell count of the two testing strains was reduced from 109cfu/mL to 106cfu/mL.Result also shows that the content of phenol absorbed on the two L.pentosus strain cells has reached between 0.42μg/mL to 1.47μg/mL,the content of p-cresol is between 0.90μg/mL to 1.28μg/mL,which means the bacteria has quite good ability of absorb the two mutagenic substances.