土壤原位硒及外源硒处理下土壤微生物群落特征分析

Characteristics of soil microbial communities treated with orthotopic and exogenous selenium

本研究采用野外原位硒研究和实验室外源硒控制实验结合的方法,利用磷脂脂肪酸(phospholipid fatty acid,PLFA)法表征土壤微生物组成并对其定量,探究土壤硒对微生物群落特征的影响的定量关系.结果表明,土壤微生物总量、革兰氏阳性菌和革兰氏阴性菌的量均与原位硒含量(范围0.101—4.563 mg·kg^(−1))呈显著正相关,同时其与土壤总氮和总有机碳呈极显著正相关.室内外源硒控制实验中,在短期培养(培养2 d)时,随着外源硒浓度的增大,除真菌响应不显著,细菌、革兰氏阳性菌和革兰氏阴性菌含量均呈现先升高后降低的趋势.当硒含量为2.28 mg·kg^(−1)时,对革兰氏阴性菌生长繁殖的促进作用最强,对细菌、革兰氏阳性菌促进作用最强的硒含量为4.57 mg·kg^(−1).外源添加硒实验的结果同野外原位硒与土壤微生物相关性的分析结果一致.当硒含量达22.8 mg·kg^(−1)时,短期(2 d)会促进细菌增长,但长期(21 d)下则表现为显著抑制.当硒含量为32.0 mg·kg^(−1)时,不论是短期培养(2 d)还是长期培养(21 d),对细菌、革兰氏阳性菌和革兰氏阴性菌生长表现出显著抑制作用.本研究表明硒含量在一定范围可以促进土壤微生物繁殖,而过量的硒则会抑制微生物的生长,该结果可为富硒农业的可持续绿色发展提供科学依据.

This study adopted a combination of the field in situ selenium research and laboratory exogenous selenium control experiments to investigate the quantitative relationship between soil selenium and microbial community characteristics.A phospholipid fatty acid(PLFA)method was used to characterize and quantify the composition of soil microorganisms.The results showed that the total amount of soil microorganisms,Gram-positive bacteria,and Gram-negative bacteria was significantly positively correlated with the in situ selenium content(range 0.101—4.563 mg·kg^(−1))and was also significantly positively correlated with the total nitrogen and total organic carbon in the soil.In the lab exogenous selenium control experiment in the short-term culture(cultured for 2 d),with the increase of exogenous selenium concentration,except that the response of fungi was not significant,the content of bacteria,Gram-positive bacteria and Gram-negative bacteria all showed a trend of first increasing and then decreasing.When the selenium content was 2.28 mg·kg^(−1),the promotion effect on the growth and reproduction of Gram-negative bacteria was the strongest.The selenium content had the strongest promotion effect on bacteria when Gram-positive bacteria was 4.57 mg·kg^(−1).The results of the exogenous selenium addition experiment were consistent with the analysis results of the correlation between field in situ selenium and soil microorganisms.When the selenium content reached 22.8 mg·kg^(−1),short-term culture(2 d)would promote the growth of bacteria,but long-term culture(21 d)showed significant inhibition.When the selenium content was 32.0 mg·kg^(−1),both short-term culture(2 d)and long-term culture(21 d)showed significant inhibition on the growth of bacteria,Gram-positive bacteria,and Gram-negative bacteria.This study shows that selenium content in a certain range can promote the reproduction of soil microorganisms,while excessive selenium will inhibit the growth of microorganisms,which can provide the scientific basis for the sustainable green development of selenium-rich agriculture.