Biorefinery of waste lemon peel using cold adapted yeasts from Antarctic and sub-Antarctic regions

ALBANESI, A; CAVELLO, IA; FRATEBIANCHI DE LA PARRA, DANTE; MARTINEZ, A.; GARMENDIA, G.; VERO, S; CAVALITTO, S

San Martín

Simposio; The Fifth International Symposium on Environmental Biotechnology and Engineering; 2016

Instituto de Investigación e Ingeniería Ambiental (3iA), UNSAM

Lemon peel and the associated residual remnants of membranes resultingfrom juice extraction represent a significant disposal problem, especially inthose regions where lemon cultivation is a major industry. A biorefinery ismost commonly defined as a facility that integrates biomass conversionprocesses and equipment to produce fuels, power, and chemicals ideally fromwaste biomass. Lemon peel has appreciable quantities of pectin, cellulose,hemi-cellulose, and lignin. The aim of this work was to select among acollection of cold adapted yeasts those that present pectinolytic activity onpectin agar plates and study the production of enzymes under submergedfermentation using this kind of waste as substrate.One hundred and three microorganisms isolated from soil samples fromKing George Island and Tierra del Fuego province were evaluated for theirpotential to produce extracellular pectinases. Among them, only eight isolatesshowed pectinolytic activity at 20ºC but only the strains LP e9.2, LP 4.6, LP5.9 and 8E were capable to produce them at 8ºC. All the strains were previouslyidentified by 26S rDNA (D1/D2 domain) sequencing and phylogenetic analyses.Strain 8E identified as Guehomycespullulans, the strains LP e9.2 and LP 5.9 identified as Cystofilobasidium infirmominiatum and Cryptoccocus adeliensis, respectivelywere selected for enzyme production under submerged fermentation.The strains were capable to grow in presence oflemon peel. G. pullulans` maximum enzyme production was observed at 45 h ofcultivation (2.83 U/ml), for C. infirmominiatum LP e9.2 its maximum wasalso at 45 h (3.9 U/ml) and for Cryptoccocusadeliensis LP 5.9 it was at 24 h (4.8 U/ml). It could be seen that at 10ºC enzyme/sremain active. Besides polygalacturonase (PGase), presence of otherpectin-degrading enzymes in the culture supernatants was investigated. None ofthe strains produce pectin or pectate lyase activity neither rhamnogalacturonanhydrolase activity. Regarding pectin esterase activity, it was only produced byG. pullulans (0.022 U/ml). All the strains produce enzymatic poolsthat showed more activity against highly esterified pectin than against pectin with63% of methylation. This behavior could be attributed in the case of G. pullulansto the presence not only of polygalacturonase enzymes but also to the presenceof pectin esterase activity. In the case of C.infirmominiatum the presence ofpolymethylgalacturonase activity (PMGase) in its supernatant is highly probable.While in C. adeliensis LP 5.9 supernatant the presence of PGase and PMGase isprobably the reason of the enzymatic profile found. b-glucosidaseactivity was detected in all the supernatants. This is the first report of the production ofpectinolytic enzymes by these species of yeasts. Inulinase, xylanase and cellulaseactivities were also detected in G. pullulans supernatants