title: High-yield production of a low-temperature-active polygalacturonase for papaya juice clarification.
abstract: A novel endo-polygalacturonase (endo-PG I) from Achaetomium sp. Xz8 was identified, overexpressed in Pichia pastoris, and characterized in this report. Recombinant endo-PG I is distinguished from other enzyme counterparts by its high activity towards polygalacturonic acid (49,934 U/ml) and high yield in the 15-l fermentor (2.13 g/l). It exhibits optimal activity at 45 °C and remained active over a broad temperature range of 0-80 °C. Distinct from most fungal polygalacturonases that have acidic pH optima, endo-PG I is optimally active at pH 6, similar to the pH of fresh papaya juice (5.7). Endo-PG I alone reduced the viscosity of papaya juice by 17.6%, and increased its transmittance by 59.1%. When combined with a commercial pectin methylesterase, it showed much higher efficiency with a synergy degree of more than 1.25. All these favourable enzymatic properties make endo-PG I attractive for potential applications in the juice industry.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Tu
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Bai
authors.forename: Pengjun
authors.initials: P
authors.lastname: Shi
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D001628:Beverages / Q000032:analysis*; D029441:Carica / Q000737:chemistry*; D003001:Cloning, Molecular; D003080:Cold Temperature; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D011096:Polygalacturonase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004718:Saccharomycetales / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D011096:Polygalacturonase
keywords: Achaetomium sp. Xz8; Endo-polygalacturonase; High specific activity; Juice clarification; Low-temperature-active