title: Use of quantitative and conventional PCR to assess biodegradation of bovine and plant DNA during cattle mortality composting.
abstract: Understanding mortality composting requires assessing the biodegradation efficacy of carcasses and other materials of animal and plant origin. Biosecure (plastic-wrapped) compost structures were built containing 16 cattle carcasses placed on 40 cm straw and covered with 160-cm of feedlot manure. Compost was collected from depths of 80 and 160 cm (P80, P160) and DNA degradation assessed over 147 days of static composting, and during 180 days of active composting. Residual soft tissues from carcasses were collected on day 147. At P80, copies of a 171-bp bovine mitochondrial DNA (Mt171) and 138-bp plant Rubisco gene fragment (Rub138) were reduced compared to initial copy numbers (CN) by 79% and 99% after 147 days, respectively. At P160, Mt171, and Rub138 decreased compared to initial CN by 20% and 99% by day 147, respectively. After 327 days, degradation of Mt171 increased to 91% compared to initial CN. Compared to fresh tissues, residual tissues at day 147 had a 99% reduction in genomic DNA yield. Yield of DNA was related to copies of a 760-bp bovine mitochondrial fragment (Mt760) which were > 93% reduced at both P80 and P160 after 147 day. Secondary composting improved decomposition of bovine tissues and Mt760 was not detectable after 207 days. A 99% reduction in genomic DNA of composted tissue and > 93% reduction of Mt760 suggests almost complete decomposition of carcass soft tissue after 147 days.
authors.affiliation: Department of Bioscience and Biotechnology, DalianUniversity of Technology, Dalian 116024, China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Xu
authors.forename: Tim
authors.initials: T
authors.lastname: Reuter
authors.forename: Yongping
authors.initials: Y
authors.lastname: Xu
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Alexander
authors.forename: Brandon
authors.initials: B
authors.lastname: Gilroyed
authors.forename: Liji
authors.initials: L
authors.lastname: Jin
authors.forename: Kim
authors.initials: K
authors.lastname: Stanford
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Larney
authors.forename: Tim A
authors.initials: TA
authors.lastname: McAllister
mesh_terms: D000818:Animals; D020029:Base Pairing; D001673:Biodegradation, Environmental; D002417:Cattle; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism*; D012037:Refuse Disposal; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012987:Soil; D013696:Temperature
chemical_list: D004272:DNA, Mitochondrial; D018744:DNA, Plant; D012987:Soil