title: Survival of multidrug-resistant bacteria in thermophilic and mesophilic anaerobic co-digestion of dairy manure and waste milk.
abstract: Anaerobic digestion is considered as a promising method to manage animal waste with antibiotic-resistant bacteria. Current research was conducted to investigate the survival of multidrug-resistant bacteria (MDRB) resistant to three groups of antibiotics: (i) cefazolin, neomycin, vancomycin, kanamycin (group 1); (ii) penicillin, oxytetracycline, ampicillin, streptomycin (group 2); and (iii) cefazolin, neomycin, vancomycin, kanamycin, penicillin, oxytetracycline, ampicillin, streptomycin (group 3), in anaerobic digestion of dairy manure and co-digestion of dairy manure and waste milk at 37°C and 55°C for 22 days, respectively. The population densities of three groups of MDRB on peptone, tryptone, yeast and glucose agar plates incubated at 30°C for 7 days before and after digestion showed 100% destruction in both digestates at thermophilic temperature. Overall reduction of more than 90% of three groups of MDRB was observed in mesophilic digestion with no significant differences (P > 0.05) between manure and milk mixture. Co-digestion of dairy manure and waste milk always produced significantly (P < 0.05) higher total gas and methane gas than digestion of manure alone at both temperatures. Gas production in each case was significantly (P < 0.05) higher in thermophilic digestion than in mesophilic digestion. The results demonstrate that thermophilic co-digestion of dairy manure and waste milk offers more benefits in terms of the environment and economy.
authors.affiliation: Department of Environmental Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Nilmini
authors.initials: N
authors.lastname: Beneragama
authors.affiliation: Department of Environmental Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iwasaki
authors.affiliation: Department of Environmental Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Suraju A
authors.initials: SA
authors.lastname: Lateef
authors.affiliation: Department of Environmental Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Takaki
authors.initials: T
authors.lastname: Yamashiro
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Kobe, Japan.
authors.forename: Ikko
authors.initials: I
authors.lastname: Ihara
authors.affiliation: Department of Environmental Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Umetsu
mesh_terms: D000693:Anaerobiosis / Q000502:physiology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D002417:Cattle; D024901:Drug Resistance, Multiple, Bacterial; D008372:Manure / Q000382:microbiology*; D008697:Methane; D008892:Milk / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D008372:Manure; D008697:Methane