植物乳杆菌X7021吸附重金属和降解亚硝酸盐能力的研究

目的 为了发掘植物乳杆菌X7021在食品发酵剂和益生菌方面的应用潜力, 本文研究了该菌株吸附重金属与降解亚硝酸盐的能力 。方法 采用分光光度法检测Cu2+和亚硝酸盐含量, 采用石墨炉原子吸收分光光度法检测Cd2+和Pb2+含量。探讨pH、温度、吸附时间和离子浓度等因素对植物乳杆菌X7021吸附重金属能力的影响, 以及亚硝酸盐浓度对其生长和降解能力的影响。结果 植物乳杆菌X7021对重金属的吸附率和吸附量均受到吸附条件的影响。首先，吸附量随着金属离子浓度的增加而增加, 而吸附率呈现出先快速下降后趋于平缓的趋势。其次, 吸附率和吸附量均随吸附时间增加而增加, 且植物乳杆菌X7021对Pb2+的吸附量明显优于Cu2+、和Cd2+。第三, Cu2+、Cd2+和Pb2+的最大吸附率分别在pH=7、7和6；且温度为37 °C时, 三种重金属离子的吸附率和吸附量均达到最大。除此之外, 植物乳杆菌X7021在24 h内几乎完全降解100 mg/L NaNO2, 且可耐受浓度高达700 mg/L的亚硝酸盐。结论 植物乳杆菌X7021能够有效吸附Cu2+、Cd2+、Pd2+等重金属离子, 且对亚硝酸盐有较强的降解和耐受能力, 在发酵食品及益生菌领域具有潜在的应用前景。

Study on the ability of Lactobacillus plantarum X7021 in the adsorption of heavy metals and degradation of nitrite

Objective In order to explore the application potential of Lactobacillus plantarum X7021 in food starter culture and probiotics, its abilities on adsorbing heavy metals and degrading nitrites were studied. Methods Cu2+ and nitrites were detected by spectrophotometry, and Cd2+ and Pb2+ were detected by graphite furnace atomic absorption spectrophotometry. Furthermore, effects of time, pH, temperature and heavy metal ions concentration on the adsorption ratio and capacity and effects of nitrite concentration on its growth and degradation ability were investigated. Results Both the adsorption ratio and capacity of L. plantarum X7021on heavy metal ions were affected by many factors. Firstly, the adsorption capacity increased with the increase of the metal ions concentration, while the adsorption ratio showed a rapid decline firstly and then came to stable. Secondly, the adsorption ratio and capacity increased with increasing adsorption time, and the adsorption capacity of Pb2+ by Lactobacillus plantarum X7021 was significantly higher than Cu2+ and Cd2+. Thirdly, the maximum adsorption ratio of Cu2+, Cd2+ and Pb2+ were at pH 7, 7 and 6, respectively, and the adsorption ratio and capacity of the three heavy metal ions reached the maximum at 37 °C. In addition, L. plantarum X7021 almost degraded 100 mg/L NaNO2 within 24 h completely, and could tolerate nitrite with a concentration up to 700 mg/L. Conclusion L. plantarum X7021 could effectively adsorb Cu2+, Cd2+ and Pd2+, and had a strong ability to degrade and tolerate nitrite, so it has a promising application in fermented food and probiotics.