| Antibiotics fermentation dregs are the solid waste produced in the manufacturing process of Ferment Antibiotics.With high protein,organic material,organic acid and so on, they are supposed to be a kind of potential resources. But they are grouped into the hazardous wastes in China because of residual antibiotics and the metabolites of antibiotics. The inappropriate treatments on these wastes will cause ecological hazard and environmental pollution. So it is extremely essential to evaluate the safety of the treatments on antibiotics fermentation dregs. The method of analytical chemistry and molecular biology were used in this study. The aim of this study was to evaluate the ecological safety of turning into feedstuffs and mixed depositing to treat penicillin fermentation dregs, based on the research of the influence of penicillin on soil microbial community, the influence of fermentation dregs on gut microorganism and the effect of co-digestion fermentation dregs with sludge on environmental microorganism.To investigated the degradation rule of penicillin and changes in microbial diversity in soil, penicillin was added into the soil samples at final concentrations of 0, 2,20,200,400,800mg/kg and sampled on day 0,3,7.The results showed that, in each group, penicillin degraded 50% on day 1,approximately. The penicillin could not be detected after 3 days by high performance liquid chromatography(HPLC). Research based on the Biolog-Eco show that the metabolic mechanism of carbon source of soil microbial community showed a visible change under the stress of high concentration of penicillin G (400,800mg/kg), the bacterial that can degrade Phenolic compounds became the predominant bacteria. But the Average Well Color Development(AWCD) showed no significant difference, indicat that penicillin had no visible effect on the total microbial activity. The Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis revealed that Shannon-Wiener diversity index was significantly lower(P<0.05) than control group(0mg/kg) when the soil was treated with high dose(800mg/kg) of penicillin G for 3 days, however, the effect disappeared after 7 days. The dominant DNA bands were reamplified and sequenced, then compared with the database in GeneBank (NCBI). The results showed that the band matched to Burkholderiales bacterium that resistance to penicillin was always detected in each treatment on day 0,3,7. The bands matched to Bacillus niabensis or Agromyces lapidis were suppressed after 3,7 days when the concentration of penicillin above 2mg/kg. Besides, after 7 days, each group found the dominant bacteria Sphingomonas roseiflava resistance to penicillin except the control set (Omg/kg). Therefore, the penicillin stress had significant inhibitory effect on soil microbial diversity, under the penicillin selection pressure, bacterium resistance to penicillin could be enrichment and became the dominant bacteria.The dry penicillin fermentation dregs(contain 2.38±0.13mg/g penicillin residu) and commercial feed were mixed at the rate of 1:99 (group1),3:97 (group2) and 0:100 (group3) in mass. The rats were feeded with the three kinds of mixed feed for 90 days. Penicillin residues in the rat feces and liver tissue was detected by HPLC on day 30,60,90.However, penicillin could not be detected in any groups on day 30,60,90. The dendrogram of the PCR-DGGE DNA profiles indicated that, to some degree, the community structure changed in each goup on day 30,60,90. The dominant DNA bands were sequenced, the results showed that the specific bands in group2 on day 30 and 90 matched closely to Akkermansia muciniphila and Roseburia hominis, respectively, both resistance to penicillin.The specific bands in group3 on day 30 and 90 both matched closely to Robinsoniellapeoriensis, which is sensitive to penicillin. Therefore, although no penicillin residues could be detected in rat tissues after feeded with mixed feed, under the penicillin stress, gut microbes resistance to penicillin could be enrichment and became the dominant bacteria.The penicillin fermentation dregs (wet,contain 1.09±0.58mg/kg penicillin residu) and sewage sludge (from the secondary sedimentation tank of municipal wastewater treatment plant) were mixed at the rate of 0:1(groupl),1:2(group2) and 1:1(group3) in mass and co-digestion.Samples was collected on day 0,3,7,20,60. Then penicillin residues and microbial diversity were analyzed. The results showed that penicillin could not be detected in each group on day 7 by HPLC. The PCR-DGGE analysis indicated that the microbial diversity was reduced first and increased later in each group. Compared with the group1 that without penicillin fermentation dregs, in group 2 or 3, bands matched most closely to Megasphaera elsdenii, Lactobacillus curvatus were detected on day 3. Both of the two bacteria can utilize complex macromolecular polymer and the major fermentation end products were monomer or small molecule compound. Besides, bands matched most closely to Clostridium jejuense, Sporanaerobacter acetigenes, Peptostreptococcus russellii, Peptostreptococcus anaerobius were detected on day 7. All of these bacteria mainly used small molecule organic matter or monomer and the major fermentation end products were formic acid, acetic acid and so on.Most of other sequences were affiliated with uncultured. The dominant DNA bands sequenced on day 20 showed the same results as these on day 7,on the whole. While, on day 60, all the dominant DNA bands matched most closely to uncultured bacterium clones. Therefore, when the penicillin fermentation dregs mixed with the sewage sludge and blended burying, penicillin can degrad rapidly, the microbial species and their metabolic type may become more abundant than the control group, and it is helpful to degradation of organic matter.In conclusion, no matter the penicillin fermentation dregs turning into feedstuffs or co-digestion with the sewage sludge, penicillin will not residual in organisms or environment for long term, but it has the potential to influence microbial diversity and structure to a certain extent. Such as the abundance of the bacterial resistance to penicillin can be increased or the metabolic patterns be changed. Therefore, the combined effect of the way for penicillin fermentation dregs utilization should do further research. |
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