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 == Publication Abstract from PubMed ==
-The enzymatic hydrolysis of the biodegradable polyester ecoflex and of a variety of oligomeric and polymeric ecoflex model substrates was investigated. For this purpose, substrate specificities of two enzymes of typical compost inhabitants, namely a fungal cutinase from Humicola insolens (HiC) and a bacterial cutinase from Thermobifida cellulosilytica (Thc_Cut1) were compared. Model substrates were systematically designed with variations of the chain length of the alcohol and the acid as well as with varying content of the aromatic constituent terephthalic acid (Ta). HPLC/MS identification and quantification of the hydrolysis products terephthalic acid (Ta), benzoic acid (Ba), adipic acid (Ada), mono(4-hydroxybutyl) terephthalate (BTa), mono-(2-hydroxyethyl) terephthalate (ETa), mono-(6-hydroxyhexyl) terephthalate (HTa) and bis(4-hydroxybutyl) terephthalate (BTaB) indicated that these enzymes indeed hydrolyze the tested esters. Shorter terminal chain length acids but longer chain length alcohols in oligomeric model substrates were generally hydrolyzed more efficiently. Thc_Cut1 hydrolyzed aromatic ester bonds more efficiently than HiC resulting in up to 3-fold higher concentrations of the monomeric hydrolysis product Ta. Nevertheless, HiC exhibited a higher overall hydrolytic activity on the tested polyesters, resulting in 2-fold higher concentration of released molecules. Thermogravimetry and differential scanning calorimetry (TG-DSC) of the polymeric model substrates revealed a general trend that a lower difference between melting temperature (Tm) and the temperature at which the enzymatic degradation takes place resulted in higher susceptibility to enzymatic hydrolysis.
+Recently, a variety of biodegradable polymers have been developed as alternatives to recalcitrant materials. Although many studies on polyester biodegradability have focused on aerobic environments, there is much less known on biodegradation of polyesters in natural and artificial anaerobic habitats. Consequently, the potential of anaerobic biogas sludge to hydrolyze the synthetic compostable polyester PBAT (poly(butylene adipate-co-butylene terephthalate) was evaluated in this study. On the basis of reverse-phase high-performance liquid chromatography (RP-HPLC) analysis, accumulation of terephthalic acid (Ta) was observed in all anaerobic batches within the first 14 days. Thereafter, a decline of Ta was observed, which occurred presumably due to consumption by the microbial population. The esterase Chath_Est1 from the anaerobic risk 1 strain Clostridium hathewayi DSM-13479 was found to hydrolyze PBAT. Detailed characterization of this esterase including elucidation of the crystal structure was performed. The crystal structure indicates that Chath_Est1 belongs to the alpha/beta-hydrolases family. This study gives a clear hint that also micro-organisms in anaerobic habitats can degrade manmade PBAT.
-Substrate specificities of cutinases on aliphatic-aromatic polyesters and on their model substrates.,Perz V, Bleymaier K, Sinkel C, Kueper U, Bonnekessel M, Ribitsch D, Guebitz GM N Biotechnol. 2016 Mar 25;33(2):295-304. doi: 10.1016/j.nbt.2015.11.004. Epub, 2015 Nov 21. PMID:26594021<ref>PMID:26594021</ref>
+An Esterase from Anaerobic Clostridium hathewayi Can Hydrolyze Aliphatic-Aromatic Polyesters.,Perz V, Hromic A, Baumschlager A, Steinkellner G, Pavkov-Keller T, Gruber K, Bleymaier K, Zitzenbacher S, Zankel A, Mayrhofer C, Sinkel C, Kueper U, Schlegel K, Ribitsch D, Guebitz GM Environ Sci Technol. 2016 Feb 29. PMID:26878094<ref>PMID:26878094</ref>
 From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>