This study examined the dissolved organic matter(DOM) components of cow dung using a combination of fluorescence(excitation–emission matrix,EEM)spectroscopy and parallel factor(PARAFAC) modelling along with eleven tr...This study examined the dissolved organic matter(DOM) components of cow dung using a combination of fluorescence(excitation–emission matrix,EEM)spectroscopy and parallel factor(PARAFAC) modelling along with eleven trace metals using ICP-MS and nutrients(NH_4^+ and NO_3^-) using an AA3 auto analyser. EEM–PARAFAC analysis demonstrated that cow dung predominantly contained only one fluorescent DOM component with two fluorescence peaks(Ex/Em=275/311 nm and Ex/Em=220/311 nm),which could be denoted as tyrosine by comparison with its standard. Occurrence of tyrosine can be further confirmed by the FTIR spectra. Trace metals analysis revealed that Na,K and Mg were significantly higher than Ca,Fe,Mn,Zn Sr,Cu,Ni and Co. The NH_4^+ concentrations were substantially higher than NO_3^-.These results thus indicate that the dissolved components of the cow dung could be useful for better understanding its future uses in various important purposes.展开更多
Recent studies have suggested that there may be a link between the use of in-feed antibiotics and the prevalence of antibiotic-resistant bacteria in human infections. It is believed that anaerobic digestion is a poten...Recent studies have suggested that there may be a link between the use of in-feed antibiotics and the prevalence of antibiotic-resistant bacteria in human infections. It is believed that anaerobic digestion is a potent method to reduce the antibiotic resistant bacteria present in waste from concentrated animal feeding operations. Cefazolin is a β-1actam antibiotic that is frequently used to treat the cows with mastitis in the Obihiro University herd. Disposal of untreated milk containing cefazolin residues promotes the occurrence of cefazolin resistant bacteria in the vicinity of farm, thus the objective of this study was to investigate the survival of antibiotic resistant bacteria in co-digestion of dairy manure and waste milk obtained from cows treated for mastitis with cefazolin under thermophilic conditions （55 ~C）. Cow manure, digested slurry and waste milk （cefazolin residue concentration 2.17 mg/L） were used as the materials in order to have three digester contents; 100% slurry, 50% slurry ＋ 50% manure and 50% slurry ＋ 45% manure ＋ 5% waste milk. The experiment was carried out using batch digesters （1 L） with active volume of 800 mL at 55 ℃ for 20 days to determine the survival of cefazolin resistant bacteria and to observe the digester performance by determining the bio gas and methane yield using gas chromatpgrapby. Dilution plate method was used to determine the population densities of total and cefazolin resistant bacteria at 0, 10th and 20th day of digestion. Total and cefazolin resistant bacterial counts were reduced with time by several orders until 10th day of digestion and those were almost similar at day 20th. Highest daily biogas and methane yield were observed in the digester contained slurry, manure and waste milk during early digestion period （until 5th day）. The results suggest that thermophilic co-digestion of dairy manure and waste milk would be a suitable technology for reducing antibiotic （cefazolin） resistant bacteria while obtaining better digester performance.展开更多
基金financially supported by the Key Construction Program of the National 985 Project,Tianjin University,Chinathe National Key R and D Program of China (2016YFA0601000)
文摘This study examined the dissolved organic matter(DOM) components of cow dung using a combination of fluorescence(excitation–emission matrix,EEM)spectroscopy and parallel factor(PARAFAC) modelling along with eleven trace metals using ICP-MS and nutrients(NH_4^+ and NO_3^-) using an AA3 auto analyser. EEM–PARAFAC analysis demonstrated that cow dung predominantly contained only one fluorescent DOM component with two fluorescence peaks(Ex/Em=275/311 nm and Ex/Em=220/311 nm),which could be denoted as tyrosine by comparison with its standard. Occurrence of tyrosine can be further confirmed by the FTIR spectra. Trace metals analysis revealed that Na,K and Mg were significantly higher than Ca,Fe,Mn,Zn Sr,Cu,Ni and Co. The NH_4^+ concentrations were substantially higher than NO_3^-.These results thus indicate that the dissolved components of the cow dung could be useful for better understanding its future uses in various important purposes.
文摘Recent studies have suggested that there may be a link between the use of in-feed antibiotics and the prevalence of antibiotic-resistant bacteria in human infections. It is believed that anaerobic digestion is a potent method to reduce the antibiotic resistant bacteria present in waste from concentrated animal feeding operations. Cefazolin is a β-1actam antibiotic that is frequently used to treat the cows with mastitis in the Obihiro University herd. Disposal of untreated milk containing cefazolin residues promotes the occurrence of cefazolin resistant bacteria in the vicinity of farm, thus the objective of this study was to investigate the survival of antibiotic resistant bacteria in co-digestion of dairy manure and waste milk obtained from cows treated for mastitis with cefazolin under thermophilic conditions （55 ~C）. Cow manure, digested slurry and waste milk （cefazolin residue concentration 2.17 mg/L） were used as the materials in order to have three digester contents; 100% slurry, 50% slurry ＋ 50% manure and 50% slurry ＋ 45% manure ＋ 5% waste milk. The experiment was carried out using batch digesters （1 L） with active volume of 800 mL at 55 ℃ for 20 days to determine the survival of cefazolin resistant bacteria and to observe the digester performance by determining the bio gas and methane yield using gas chromatpgrapby. Dilution plate method was used to determine the population densities of total and cefazolin resistant bacteria at 0, 10th and 20th day of digestion. Total and cefazolin resistant bacterial counts were reduced with time by several orders until 10th day of digestion and those were almost similar at day 20th. Highest daily biogas and methane yield were observed in the digester contained slurry, manure and waste milk during early digestion period （until 5th day）. The results suggest that thermophilic co-digestion of dairy manure and waste milk would be a suitable technology for reducing antibiotic （cefazolin） resistant bacteria while obtaining better digester performance.
