Biodegradation of amine waste generated from post-combustion CO2 capture in a moving bed biofilm treatment system

Nitrogen and organic matter removal from reclaimer waste of a monoethanolamine (MEA) based CO₂-capture plant was demonstrated in a pre-denitrification biofilm system. The reclaimer waste was generated from a 30 % (w/w) MEA solvent used for capturing CO₂ from flue gas from a coal-fired power plant. MEA, N-(2-hydroxylethyl)glycine (HEGly) and 2-hydroxyethylformamide (HEF) were the major contaminants treated. Hydrolysis of MEA to ammonia and further oxidation of organic intermediates readily occurred in the pre-denitrification system with a hydraulic retention time of 7 h. The biofilm system achieved 98 ± 1 % removal of MEA and 72 ± 16 % removal of total nitrogen. This is the first demonstration of efficient biodegradation of real amine waste from a post-combustion CO₂ capture facility by pre-denitrification without external electron donor.     

Probing a functional role of Glu87 and Trp89 in the lid ofHumicola lanuginosa lipase through transesterification reactions in organic solvent

To reveal the functional role of Glu87 and Trp89 in the lid ofHumicola lanuginosa lipase, site-directed mutagenesis at Glu87 and Trp89 was carried out. The catalytic performance of wild-type and mutated lipases was studied in transesterification reactions in cyclohexane at a controlled water activity. Two different acyl donors were used in the investigation: tributyrin, a natural substrate for a lipase, and vinyl butyrate, an activated ester suitable for fast and efficient lipase-catalyzed transformations in preparative organic synthesis. As acyl acceptor 1-heptanol was used. The Glu87Ala mutation decreased theV _max,app value with tributyrin and vinyl butyrate by a factor of 1.5 and 2, respectively. TheK _m,app for tributyrin was not affected by the Glu87Ala mutation, but theK _m,app for vinyl butyrate increased twofold compared to the wild-type lipase. Changing Trp89 into a Phe residue afforded an enzyme with a 2.7- and 2-fold decreasedV _max,app with the substrates tributyrin and vinyl butyrate, respectively, compared to the wild-type lipase. No significant effects on theK _m,app values for tributyrin or vinyl butyrate were seen as a result of the Trp89Phe mutation. However, the introduction of a Glu residue at position 89 in the lid increased theK _m,app for tributyrin and vinyl butyrate by a factor of >5 and 2, respectively. The Trp89Glu mutated lipase could not be saturated with tributyrin within the experimental conditions (0–680 mM) studied here. With vinyl butyrate as a substrate theV _max,app was only 6% of that obtained with wild-type enzyme.