No abstract

No abstract

No abstract

Many biotechnological processes pursuing sustainability aim for effective, inexpensive, and environmentally friendly alternatives to replace conventional practices. Laccase-containing lignocellulolytic systems from white rot fungi have been shown to be an efficient enzymatic tool for ecofriendly biological treatments. One objective of the biotechnological enzymes production process is to find optimum growing and secretion conditions for a selected fungus. In this work, different fungi isolated from the Misiones rainforest (Coriolus versicolor f. antarcticus BAFC-266, Ganoderma applanatum strain F, Phlebia brevispora BAFC-633, and Pycnoporus sanguineus BAFC-2126) were incubated at different temperatures (25, 29, 33 °C) and pH values (3.5, 4.5, 5.5) under static conditions for 7, 10, and 14 days to evaluate their growing ability and laccase (Lac) production. Results revealed specific favorable conditions for growth and protein secretion depending on the fungus under consideration, making it necessary to adjust these parameters for each particular case. The combined effect of these cultivation parameters showed a marked influence on the secreted Lac activity by P. brevispora BAFC 633, with the highest activity (~ 240 U/l) at 29 ºC and pH 4.5 at the 10 th day of cultivation. The presence of Lac isoenzymes also depended on the pH, temperature, and time of cultivation for the different tested fungi.

The technical viability was investigated for the conversion of Pinus pinaster stumps to value-added products via a chain of pretreatments and simultaneous saccharification and fermentation (SSF) steps to obtain bioethanol. Sequential steam explosion (SE), organosolv (OS) pretreatment and soda-anthraquinone pulping (Na/AQ) were performed resulting in an unbleached pulp (UBP), which was successfully converted via SSF to bioethanol with concentrations up to 79 g l−1, which corresponds to a conversion yield of 97% and productivity of 1.09 g l−1 h−1 at 15% total solids. Accordingly, delignification steps by oxygen bleaching are not necessary for bioethanol production. Different industrial softwood (SW) pulps were also tested as reference materials. Total lignin contents up to 4.5% in SW-based pulps had no adverse effects on SSF efficiency.

No abstract

No abstract

Laccases produced by white rot fungi are involved in the degradation of lignin and a broad diversity of other natural and synthetic molecules, having a great potential for biotechnological applications. They are frequently encoded by gene families, as in the basidiomycete Trametes sp. strain I-62, from which the lcc1, lcc2, and lcc3 laccase genes have been cloned and sequenced. A multiplex reverse transcription-PCR method to simultaneously study the expression of these genes was developed in this study. The assay proved to be quick, simple, highly sensitive, and reproducible and is particularly valuable when numerous samples are to be analyzed and/or if the amount of initial mRNA is limited. It was used to analyze the effect of 3,4-dimethoxybenzyl alcohol (veratryl alcohol) and two of its isomers (2,5-dimethoxybenzyl alcohol and 3,5-dimethoxybenzyl alcohol) on differential laccase gene expression in Trametes sp. strain I-62. These aromatic compounds produced different induction patterns despite their chemical similarity. We found 2,5-dimethoxybenzyl alcohol to be the best inducer of laccase activity while also producing the highest increase in gene expression; 3,5-dimethoxybenzyl alcohol was the next best inducer. Transcript amounts of each gene fluctuated dramatically in the presence of these three inducers, while the total amounts of laccase mRNAs seemed to be modulated by a coordinated regulation of the different genes.