模拟淀粉条件下乳杆菌吸附苯并芘的能力

Removal of benzo(a)pyrene by Lactobacillus strains under simulated starch conditions

摘要:

[目的] 研究了模拟淀粉条件下嗜酸乳杆菌(Lactobacillus acidophilus) NCFM、植物乳杆菌(Lactobacillus plantarum) 121以及戊糖乳酸菌(Lactobacillus pentosus) ML32吸附苯并芘的能力,为利用乳杆菌去除苯并芘提供一定的理论指导。[方法] 基于苯并芘的HPLC检测方法,考察了淀粉含量及类型、培养时间和pH等因素对乳杆菌吸附苯并芘能力的影响,研究了淀粉水解产物及菌体活性影响乳杆菌吸附苯并芘的效果。[结果] 淀粉含量在2%-10%的范围内,乳杆菌吸附苯并芘的能力与淀粉含量的增加呈正相关性,且与淀粉种类关系不大,但经糊化处理的淀粉可以促进菌体吸附苯并芘。在模拟淀粉体系中,培养前4 h时乳杆菌吸附苯并芘的效率增长快,此后其吸附率增加缓慢。淀粉经酸性(pH为3-4)和碱性(pH为8-9)处理,乳杆菌吸附苯并芘的能力提升。淀粉的水解产物麦芽糖和葡萄糖都能显著改善乳杆菌吸附苯并芘的能力。与活细胞相比,经灭活处理后乳杆菌细胞吸附苯并芘的能力降低。[结论] 在淀粉体系中,乳杆菌依然表现出良好的苯并芘吸附能力,且一定范围内淀粉含量增多、糊化作用以及麦芽糖和葡萄糖的存在可促进其吸附苯并芘的能力。因此,本研究中的乳杆菌或许可以用作生物脱除剂来减少淀粉食物中的苯并芘。

关键词:苯并芘;乳酸菌;淀粉体系;吸附

Abstract:

[Objective] The performances of Lactobacillus acidophilus NCFM, Lactobacillus plantarum121 and Lactobacillus pentosus ML32 in removing benzo(a)pyrene [B(a)P] in simulated starch conditions were studied. To provide a novel way to reduce the potential risk of B(a)P to human, several factors which affect the binding of the 3 Lactobacillus strains to the chemical toxin were investigated in starch system. [Methods] The percentage of B(a)P bound by Lactobacillus strains was determined with HPLC after incubation at 37℃ for 4 h. The B(a)P-removing capabilities of Lactobacillus strains in various simulated starch systems were evaluated, including the concentrations, types and gelatinization of starch, incubation time, pH and starch-hydrolyzed products. [Results] The B(a)P-binding percentages of the Lactobacillus strains increased as starch concentrations were elevated from 2% to 10%. Starch types, either from corn, potato or sweet potato, had little effects on the ability of these bacterial cells to bind B(a)P. The gelatinization of starch favored Lactobacillus strains to bind more B(a)P. The percentage of these bacterial cells to bind B(a)P grew fast at 37℃ for the first 4 h-incubation time, and then slowly increased. The three Lactobacillus strains bound more B(a)P when starches were acidified to pH of 3 to 4 or alkalified to pH of 8 to 9. The viable cells of three Lactobacillus strains removed more B(a)P via their binding than their dead cells did. Moreover, both glucose and maltose, the end products after starch is hydrolyzed, improved significantly the performance of the 3 bacterial strains to remove B(a)P. [Conclusion] All of the three Lactobacillus strains perform good ability to bind B(a)P in the presences of starch. Their B(a)P-removing ability would be improved with an increased starch concentration, and the gelatinization of starch as well as the supplements of glucose and maltose. Thus, the selected Lactobacillus strains in our current work should be promising as a biological agent to reduce the occurrence of B(a)P in starch-based food products.

Key words:benzo(a)pyrene;Lactobacillus strains;starch system;binding