The Cerrena unicolor BCC306 - new potent producer of lignin-modifying enzymes
Keywords:Basidiomycetes, Cerrena unicolor, Submerged fermentation, Lignin-modifying enzymes, Mandarin peels, Biotechnological applications.
In this study, the nutritional requirements of Cerrena unicolor BCC306 providing enhanced production of lignin-modifying enzymes have been elucidated in the submerged fermentation of plant raw materials. Mandarin peels followed by the wheat bran and pomegranate residues manifold enhanced laccase production. All tested lignocellulosic materials 2-6-fold stimulated secretion of phenol red oxidizing manganese peroxidase (MnP610) as compared with the control medium, only mandarin peels more than 3-fold increased the Mn oxidizing manganese peroxidase (MnP270) activity whereas addition of pomegranate or wheat straw 5- and 11-fold decreased this enzyme activity, respectively. Mandarin peels and pomegranate ensured accumulation of appreciated levels of extracellular lignin peroxidase (LiP). Variation of mandarin peels concentration from 0 to 6% revealed that the higher was the growth substrate concentration the higher was enzyme activity. Supplementation of mandarin peels-based medium with an additional nitrogen source (20 mM N) favored of laccase secretion, none of them increased MnP610 activity and only peptone and casein hydrolysate enhanced the MnP270 activity. The highest LiP activity was revealed during the fungus cultivation in the medium supplemented with KNO3 as an additional nitrogen source. Cultivation of C. unicolor 306 in 7 L laboratory fermenter resulted in accumulation of 302.4 U/mL laccase, 4.9 U/mL MnP270, 0.96 U/mL of MnP610, and 0.29 U/mL LiP indicating that this fungus is a good candidate for scaled up production of LME for different biotechnological applications.