氧化亚铁硫杆菌(Thiobacillus ferrooxidans)对重金属富集植物腐蚀作用研究

为了获得重金属富集植物生物法预处理的最佳工艺条件,实现其资源化利用,以黑麦草(Lolium perenne)为材料,探究氧化亚铁硫杆菌(Thiobacillus ferrooxidans,T.f)在不同接种量和不同浓度底物添加剂(S0、Na2S2O_3、Fe SO4、Fe S和Fe0)条件下对黑麦草的腐蚀作用,通过扫描电镜进一步观察其对细胞壁的破坏情况。结果表明:氧化亚铁硫杆菌对黑麦草具有较好的腐蚀作用,各接种量(5%~15%)之间差异较小,反应第10 d,10%接种量处理组中黑麦草的纤维素降解率达40.97%,半纤维素降解率达77.49%,木质素降解率达19.33%。投加底物添加剂后,氧化亚铁硫杆菌对纤维素降解率有明显提高。总体来看,添加14 g·L~(-1)的S0对黑麦草的降解效果较好,纤维素、半纤维素及木质素的降解率分别达到81.31%、82.29%、26.02%,此条件下铀、铬、镉的浸出效率均较高。在氧化亚铁硫杆菌及底物添加剂的作用下,除Fe S、Fe0处理组外,其他各处理组的pH值均呈下降趋势,反应10 d后,pH值最低降至1.0左右,pH值的降低能有效提高半纤维素降解率,但与纤维素及木质素的降解率无明显关系。扫描电镜结果表明氧化亚铁硫杆菌对黑麦草细胞壁有较强的破坏作用。氧化亚铁硫杆菌对黑麦草具有很好的腐蚀效果,并且能充分利用底物添加剂提高黑麦草中纤维素降解率。后期需进一步考虑提高氧化亚铁硫杆菌对木质素的降解效率及黑麦草中重金属的回收率。

The corrosive effects of Thiobacillus ferrooxidans on heavy metal-enriched plant

In order to obtain the optimal processing conditions and solve the resource utilization for the biological pretreatment of heavy metal-enriched plants, this paper explored the corrosive behavior of ryegrass(Lolium perenne) inoculated Thiobacillus ferrooxidans(T.f) under different concentrations of substrates(including S⁰, Na₂S₂O₃, FeSO₄, FeS and Fe⁰) conditions. Destruction of the cell wall structure of ryegrass was detected by scanning electron microscopy. The results showed that T.f had strong corrosion effect on ryegrass. There was no significant difference of degradation effect in inoculation amount(5%~10%) of T.f. At the 10^th day, the cellulose digestibility, hemicellulose digestibility, and lignin digestibility of ryegrass were 40.97%, 77.49%, and 19.33%, respectively with 10% T.f. After supplementing different substrates with T.f, the digestibility of cellulose was significantly improved. Overall, the digestibility of ryegrass was better at the dosing quanlity of S⁰ was 14 g·L^-1. In this case, the digestibility of cellulose, hemicellulose and lignin of ryegrass can be up to 81.31%, 82.29% and 26.02%, respectively. Meanwhile, the recovery efficiency of uranium, chromium and cadmium were high. Under the mutual influences of T.f and different substrates, the pH of all substrates groups declined dramatically, except the groups of FeS and Fe⁰. The lowest value of pH was about 1.0 at the 10^th day. The results showed that the decrease of pH could effectively increase the digestibility of hemicelluloses, but no significant relationship on the cellulose and lignin. Futhermore, T.f had strong destructive action on the cell wall structure of ryegrass detected by the scanning electron microscope. T.f made strong corrosion on ryegrass and combined with making full use of the substrates, it could improve the digestibility of cellulose of ryegrass. To summary, the study on both corrosion efficiency of lignin and recovery efficiency of heavy metals will be improved in the further.