Diversity of polyester-degrading bacteria in compost and molecular analysis of a thermoactive esterase from Thermobifida alba AHK119

• Published in: Applied microbiology and biotechnology Vol. 87; no. 2; pp. 771 - 779
• Main Authors: Hu, Xiaoping, Thumarat, Uschara, Zhang, Xian, Tang, Ming, Kawai, Fusako
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2010; Springer; Springer Nature B.V
• Subjects: Actinomycetales; Actinomycetales - enzymology; Actinomycetales - genetics; Actinomycetales - isolation & purification; Actinomycetales - metabolism; Actinomycetes; Amino Acid Sequence; Amino acids; Bacillus; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Bacterial Proteins; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biodegradable materials; Biodegradation; Biodiversity; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Chemical reactions; Chemicals; chemistry; classification; Cloning; Cloning, Molecular; Composting; composts; Conserved sequence; E coli; Environmental Biotechnology; Enzyme Stability; Enzymes; enzymology; Escherichia coli; Esterase; Esterases; Esterases - chemistry; Esterases - genetics; Esterases - metabolism; Esters; Fundamental and applied biological sciences. Psychology; genes; genetics; Hot Temperature; isolation & purification; Life Sciences; Lipase; metabolism; Microbial Genetics and Genomics; Microbiology; Microorganisms; Molecular Sequence Data; Molecular weight; Particle size; Plastics; Polyesters; Polyesters - metabolism; Polyethylene terephthalate; Polymer films; Polymers; Proteins; Sequence Homology, Amino Acid; signal peptide; Soil Microbiology; Studies; Terephthalic acid; Thermobifida alba; triacylglycerol lipase; Aliphatic-aromatic copolyester degraders; Serine hydrolase; strain AHK119; Thermophilic bacteria in compost; Thermoactive esterase; Compost; Enzyme; Aliphatic compound; Thermobifida alba strain AHK119; Serine; Diversity; Ester polymer; Thermophily; Esterases; Degradation; Hydrolases; Bacteria
• ISSN: 0175-7598; 1432-0614; 1432-0614
• DOI: 10.1007/s00253-010-2555-x

More than 100 bacterial strains were isolated from composted polyester films and categorized into two groups, Actinomycetes (four genera) and Bacillus (three genera). Of these isolates, Thermobifida alba strain AHK119 (AB298783) was shown to possess the ability to significantly degrade aliphatic-aromatic copolyester film as well as decreasing the polymer particle sizes when grown at 50°C on LB medium supplemented with polymer particles, yielding terephthalic acid. The esterase gene ( est119 , 903 bp, encoding a signal peptide and a mature protein of 34 and 266 amino acids, respectively) was cloned from AHK119. The Est119 sequence contains a conserved lipase box (–G-X-S-X-G-) and a catalytic triad (Ser129, His207, and Asp175). Furthermore, Tyr59 and Met130 likely form an oxyanion hole. The recombinant enzyme was purified from cell-free extracts of Escherichia coli Rosetta-gami B (DE3) harboring pQE80L- est119 . The enzyme is a monomeric protein of ca. 30 kDa, which is active from 20°C to 75°C (with an optimal range of 45 to 55°C) and in a pH range of 5.5 to 7.0 (with an optimal pH of 6.0). Its preferred substrate among the p -nitrophenyl acyl esters (C 2 to C 8 ) is p -nitrophenyl hexanoate (C 6 ), indicating that the enzyme is an esterase rather than a lipase.