恩诺沙星对厌氧发酵过程中水解酶活性及 沼气产量的影响

兽用抗生素因其具有防病、促生长的作用被广泛应用于畜禽养殖业,而在畜禽粪便发酵生产沼气的过程中,残留在畜禽粪便中的抗生素可能会抑制沼气发酵过程。该文以猪粪和玉米秸秆为原料,采用自行设计的恒温厌氧发酵装置,研究了外源添加恩诺沙星(ENR)对猪粪厌氧发酵过程中水解酶活性及产气量的影响。结果表明,添加20 mg·kg?1、60 mg·kg?1和120 mg·kg?1恩诺沙星条件下,猪粪厌氧发酵初期不同浓度恩诺沙星对纤维素酶和脲酶活性有显著抑制作用(P0.05);厌氧发酵的前15 d,添加20 mg·kg?1恩诺沙星对蔗糖酶活性有一定的激活作用(P0.05),添加60 mg·kg?1和120 mg·kg?1的恩诺沙星对蔗糖酶活性有抑制作用(P0.05);猪粪厌氧发酵后期,恩诺沙星对纤维素酶、脲酶和蔗糖酶活性影响不显著(P0.05)。在发酵产气速率增长期的第5~11 d和21~31 d,添加20 mg·kg?1、60 mg·kg?1和120 mg·kg?1恩诺沙星对沼气产气速率有明显抑制作用(P0.05);而在发酵的第31 d后,添加各浓度恩诺沙星对沼气产气速率影响不大。在整个50 d的厌氧发酵过程中,与不添加恩诺沙星的对照相比,添加20 mg·kg?1、60 mg·kg?1和120 mg·kg?1恩诺沙星处理的总产气量分别减少7.38%、12.08%和15.77%。可见,恩诺沙星影响了猪粪厌氧发酵过程中水解酶活性和沼气产气速率及产气量,在厌氧发酵不同阶段,恩诺沙星对不同水解酶活性和产气速率影响也不同。该文研究结果可为无害化处理含恩诺沙星的畜禽粪便及提高厌氧发酵效率提供参考。

Effects of Enrofloxacin on hydrolytic enzyme activities and biogas production during anaerobic fermentation

AbstractVeterinary antibiotics are widely used as feed additives in domestic animal rearing either to improve growth performance or to prevent disease infection. A wide range of antibiotics is excreted unchanged in urine and feces of animals, posing potential human and ecological health risks after entering the environment. This is confirmed by the presence of widespread detectable antibiotic concentrations in surface waters and manure. Antibiotics originating in manure from livestock operations are a concern because they remain bioactive. Anaerobic digestion is one of the most promising biotechnologies for the conversion of diverse organic substrates, ranging from high solid feedstocks (animal manure, food waste and municipal solid waste) to municipal and industrial wastewaters and to energy-rich biogas. Most of the biogas plants in China are run on animal manure to reduce biological oxygen demand and to produce biogas. After ingestion by animals, some of the compounds are excreted along with the manure which may inhibit biogas process when manure is used as substrate in biogas plants. Most studies on antibiotic inhibition under anaerobic fermentation have focused on animal manure as substrate, showing significant anaerobic fermentation inhibition primarily at higher antibiotic concentrations typically found in manure. An experiment was therefore designed to study the effects of Enrofloxacin (ENR) addition to pig manure on hydrolytic enzyme activities and biogas production in anaerobic fermentation processes with pig manure and corn stalks as raw materials. The results showed that pig manure anaerobic fermentation added with 20 mg·kg?1, 60 mg·kg?1 and 120 mg·kg?1 ENR inhibited cellulose and urease activities at the initial stage of anaerobic fermentation (P <0.05). However, the addition of 20 mg·kg?1 ENR promoted the activities of sucrose, while the addition of 60 mg·kg?1 and 120 mg·kg?1 ENR inhibited the activities of sucrase in the first 15 days (P< 0.05). The effects of ENR on cellulase, urease and sucrose activities were not statistically different in the late stage of anaerobic fermentation (P >0.05). Pig manure-based anaerobic fermentation with 20 mg·kg?1, 60 mg·kg?1 and 120 mg·kg?1 ENR significantly inhibited gas production rate during 5?11 days and 21?31 days (P <0.05) of anaerobic fermentation. Compared with control (no ENR application), the gas production rate had no obvious changes in 20 mg·kg?1, 60 mg·kg?1 and 120 mg·kg?1 ENR treatments after 31 days of anaerobic fermentation. Furthermore, biogas yield decreased by 7.38%, 12.08% and 15.77%, respectively, in 20 mg·kg?1, 60 mg·kg?1 and 120 mg·kg?1ENR treatments during anaerobic fermentation for 50 days. It was obvious that ENR influenced hydrolytic enzyme activities, gas production rate and biogas production during anaerobic fermentation. The effects of ENR on different hydrolytic enzyme activities and gas production rate were also different at different stages of anaerobic fermentation. The results provided a reference for harmless disposal of animal manure containing ENR and for improvement of anaerobic fermentation efficiency.