A p-coumaroyl esterase from Rhizoctonia solani with a pronounced chlorogenic acid esterase activity

Publication date: Available online 31 January 2017
Source:New Biotechnology
Author(s): Annabel Nieter, Sebastian Kelle, Diana Linke, Ralf G. Berger
Extracellular esterase activity was detected in submerged cultures of Rhizoctonia solani grown in the presence of sugar beet pectin or Tween 80. Putative type B feruloyl esterase (FAE) coding sequences found in the genome data of the basidiomycete were heterologously expressed in Pichia pastoris. Recombinant enzyme production on the 5-L bioreactor scale (RspCAE: 3245UL⁻¹) exceeded the productivity of the wild type strain by a factor of 800. Based on substrate specificity profiling, the purified recombinant RspCAE was classified as a p-coumaroyl esterase (pCAE) with a pronounced chlorogenic acid esterase side activity. The RspCAE was also active on methyl cinnamate, caffeate and ferulate and on feruloylated saccharides. The unprecedented substrate profile of RspCAE together with the lack of sequence similarity to known FAEs or pCAEs suggested that the RspCAE represents a new type of enzyme. Hydroxycinnamic acids were released from agro-industrial side-streams, such as destarched wheat bran (DSWB), sugar beet pectin (SBP) and coffee pulp (CP). Overnight incubation of coffee pulp with the RspCAE resulted in the efficient release of p-coumaric (100%), caffeic (100%) and ferulic acid (85%) indicating possible applications for the valorization of food processing wastes and for the enhanced degradation of lignified biomass.



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