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DTSTART:20151025T030000
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RDATE:20161030T030000
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UID:www.bayceer.uni-bayreuth.de-bayceer-t130718id
DTSTAMP:20260524T130714Z
DESCRIPTION:The accumulation of persistent synthetic organic polymers in th
 e environment has become a major environmental concern. Replacing these ma
 terials by biodegradable polymers in specific application areas may help t
 o alleviate this problem. Among these areas are agricultural practices tha
 t heavily rely on the use of plastics (i.e.\, ‘plasticulture’). This contr
 ibution focuses on assessing the factors that govern the biodegradation of
  aliphatic polyesters\, composed of alternating units of dialcohols and di
 carboxylic acids\, in agricultural soils. The contribution has three succe
 ssive parts that target three key processes involved in polyester biodegra
 dation. The first part focuses on enzymatic polyester hydrolysis\, which i
 s commonly considered the rate-limiting step in the overall biodegradation
  of these materials in soils. Two novel experimental approaches are presen
 ted and used to systematically study the hydrolysis of a series of structu
 rally related aliphatic polyesters by two isolated esterases under well-co
 ntrolled laboratory conditions. The enzymatic hydrolysis rates increased a
 s the melting temperatures of the aliphatic polyesters decreased\, strongl
 y suggesting that the flexibility of the polyester backbone and hence its 
 propensity to enter the active sites of the esterases governed hydrolysis 
 rates. The second part focuses on the mineralization dynamics of a selecte
 d\, 13C-labeled aliphatic polyester\, polybutylene succinate\, in an agric
 ultural soil under laboratory conditions. While the two monomers that comp
 ose this polyester\, 1\,4-butanediol and succinic acid\, mineralized over 
 a relatively short time (hours to days) and in a position-specific manner\
 , the mineralization of polybutylene succinate was slower (timeframe of we
 eks to months) and showed only a slight dependence on the monomer position
  at which the polymer was labeled. These findings are consistent with over
 all mineralization rates in soils being governed by the rates of enzymatic
  depolymerization of the bulk polyester and\, hence\, the rates at which m
 ono- and oligomers are released from the polymer surface to become availab
 le to soil microorganisms. The third part addresses the colonization of po
 lyester film surfaces by soil fungi and unicellular microorganisms as well
  as the uptake of polymeric carbon into microbial biomass using a combinat
 ion of surface imaging techniques. The collected images unequivocally demo
 nstrate that polymeric carbon is incorporated into microbial biomass. Furt
 hermore\, the images suggest that fungal hyphae play a key role in polyest
 er degradation. The novel insights into polyester biodegradation will be s
 ummarized and will serve to provide a brief outlook to future work on the 
 fate of biodegradable polymers in soils and other environmental systems.\n
  \n*** Invited by Stefan Peiffer\, Hydrology
DTSTART;TZID=Europe/Berlin:20160428T120000
DTEND;TZID=Europe/Berlin:20160428T133000
LOCATION:H6\, GEO
SUMMARY:Dr. Michael Sander\, Environmental Chemistry\, Institute of Biogeoc
 hemistry and Pollutant Dynamics\, ETH Zürich\, Switzerland (Homepage): Fat
 e of biodegradable polyesters in agricultural soils - from enzymatic hydro
 lysis to microbial uptake and mineralization
TRANSP:TRANSPARENT
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