| The widespread use of organic chemicals has produced large amounts of refractory organic contaminants(ROCs),which not only affect the ecological security but also seriously threatened human health.According to the polarity of different organic contaminants,environmental microorganisms with homogeneous cell-surface hydrophobicity(CSH)can effectively improve the in situ degradation efficiency of organic contaminants.ROCs are usually used as electron acceptors(EAs)in microbial anaerobic respiration.On the basis of previous studies and the pre-investigation of our team,we knew that microbial degradation characteristics for organic electron acceptors(OEAs)with different polarity were different,and proved that organic contaminants with different polarity also have impacts on microorganisms.However,the mechanisms of microbial response to OEAs with different polarity are still unclear.Therefore,this research used two commonly used azo dyes with different polarity(methyl red with low polarity and amaranth with high polarity)as the targeting OEAs,combined with cell phenotypic and physiology analysis and the next generation sequencing(NGS)technology,to explore the effects of OEAs with different polarities on the functional microbial community diversity,CSH,degradation activities.The following main conclusions and awareness were obtained:(1)According to the observation of transmission electron microscopy(TEM),the results showed that after the domestication with different polarity OEAs,the diversity in microbial species and morphological structures of the functional communities decreased,which suggested that the enrichment was effect.After the domestication by different polarity OEAs,the cell length of the microbes increased to a maximum of 120 ?m.Moreover,the microbial cell lengths domesticated under the high polarity amaranth were longer than that domesticated under the low polarity methyl red,which suggested that the high-polarity organic electron acceptors(HPOEAs)were more severe effect on microbial morphology than low-polarity organic electron acceptors(LPOEAs).(2)This study showed that both high and low polarity OEAs had influences on the CSH of the function microbial community.The CSH of initial activated sludge was 30.49± 5.37%,and after a 28 days' domestication under methyl red,amaranth and both methyl red and amaranth,the CSH of three microbial communities were 46.76 ± 6.01%?13.97 ±1.66% and 27.80 ± 9.41%,respectively.Compared with initial activated sludge,the CSH of amaranth and two-dye(amaranth and methyl red)co-domesticated microbial community were reduced by 54.18% and 8.82%,but the CSH of methyl red domesticated microbial community was by improved 53.36%.It showed that the CSH of domesticated microbialcommunity had a negative correlation to the polarity of azo dyes,and the effect of amaranth on the CSH of three kinds of domesticated microbial community was all more severe than methyl red,which indicated that the effect of HPOEAs on microbial CSH was larger than LPOEAs.(3)The removal rates of initial activated sludge on amaranth,methyl red were(16.85± 3.77)×10-7 and(248.84 ± 60.67)× 10-7 M/mg·h.After a 7 d decoloration experimentation of different OEAs by 28 d domesticated microbial communities,the removal rates of three kinds of domesticated microbial community to amaranth,methyl red were(970.00 ± 70.00)× 10-7,(892.8 ± 64.07)× 10-7,(1028.73 ± 104.62)× 10-7 M/mg·h and(1530.67 ± 223.33)× 10-7,(1639.43 ± 223.40)× 10-7,(2847.33 ± 304.50)× 10-7M/mg·h,respectively,which were increased by a factor of 55.89,51.94,60.05 times and5.15,5.89,10.44 times,respectively,compared with initial activated sludge.It showed that the effect of amaranth on the removal rates were higher than those of methyl red,and the removal rates of two-dye co-domesticated microbial community on different polarity OEAs were higher than those of single polarity OEAs domesticated microbial community.These results indicated that the effect of HPOEAs on microbial removal rates was higher than LPOEAs.(4)Different polarity OEAs had a certain influence on the structural diversity of the functional microbial community,and the effect of HPOEAs on the structural diversity of the functional microbial community was larger than LPOEAs.Tissierella soehngenia and Sedimentibacter in the HPOEAs-domesticated was predominant but not in the LPOEAs-domesticated,or even LPOEAs could inhibit their growth and functional activities.These phenomena suggested that different function microbial community had selectivity and adaptability to different polarity OEAs. |
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