Correction: Genome-wide identification, characterization and expression profile analysis of expansins gene family in sugarcane (Saccharum spp.).

[This corrects the article DOI: 10.1371/journal.pone.0191081.].

Genome-wide identification, characterization and expression profile analysis of expansins gene family in sugarcane (Saccharum spp.).

Expansins refer to a family of closely related non-enzymatic proteins found in the plant cell wall that are involved in the cell wall loosening. In addition, expansins appear to be involved in different physiological and environmental responses in plants such as leaf and stem initiation and growth, stomata opening and closing, reproduction, ripening and stress tolerance. Sugarcane (Saccharum spp.) is one of the main crops grown worldwide. Lignocellulosic biomass from sugarcane is one of the most promising raw materials for the ethanol industry. However, the efficient use of lignocellulosic biomass requires the optimization of several steps, including the access of some enzymes to the hemicellulosic matrix. The addition of expansins in an enzymatic cocktail or their genetic manipulation could drastically improve the saccharification process of feedstock biomass by weakening the hydrogen bonds between polysaccharides present in plant cell walls. In this study, the expansin gene family in sugarcane was identified and characterized by in silico analysis. Ninety two putative expansins in sugarcane (SacEXPs) were categorized in three subfamilies after phylogenetic analysis. The expression profile of some expansin genes in leaves of sugarcane in different developmental stages was also investigated. This study intended to provide suitable expansin targets for genetic manipulation of sugarcane aiming at biomass and yield improvement.

Recombinant expression of Thermobifida fusca E7 LPMO in Pichia pastoris and Escherichia coli and their functional characterization.

The discovery of lytic polysaccharides monooxygenases copper dependent (LPMOs) revolutionized the classical concept that the cleavage of cellulose is a hydrolytic process in recent years. These enzymes carry out oxidative cleavage of cellulose (and other polysaccharides), acting synergistically with cellulases and other hydrolases. In fact, LPMOs have the potential for increasing the efficiency of the lignocellulosic biomass conversion in biofuels and high value chemicals. Among a small number of microbial LPMOs that have been characterized, some LPMOs were expressed and characterized biochemically from the bacteria Thermobifida fusca, using the host Escherichia coli. In this work, the E7 LPMO protein of T. fusca was expressed both in E. coli (native DNA sequence) and Pichia pastoris (codon-optimized DNA sequence), for further analysis of oxidative cleavage, with PASC (phosphoric acid swollen cellulose) and Avicel PH-101 substrates, using mass spectrometry analysis. Mass spectra results of Avicel PH-101 and PASC cleavages by purified E7 LPMO expressed in E. coli and in P. pastoris allowed the visualization of compounds corresponding to oxidized and non-oxidized oligosaccharides. Further optimization of reactions will be performed, since it was found only one degree of polymerization (DP 7). This work demonstrated that it is possible to produce the E7 LPMO from T. fusca in the host P. pastoris, and the recombinant protein was shown to be active on cellulose. The approach used in the present work could be an alternative to produce this bacterial LPMO for cellulose cleavage.

Biodiesel biorefinery: opportunities and challenges for microbial production of fuels and chemicals from glycerol waste.

The considerable increase in biodiesel production worldwide in the last 5 years resulted in a stoichiometric increased coproduction of crude glycerol. As an excess of crude glycerol has been produced, its value on market was reduced and it is becoming a "waste-stream" instead of a valuable "coproduct". The development of biorefineries, i.e. production of chemicals and power integrated with conversion processes of biomass into biofuels, has been singled out as a way to achieve economically viable production chains, valorize residues and coproducts, and reduce industrial waste disposal. In this sense, several alternatives aimed at the use of crude glycerol to produce fuels and chemicals by microbial fermentation have been evaluated. This review summarizes different strategies employed to produce biofuels and chemicals (1,3-propanediol, 2,3-butanediol, ethanol, n-butanol, organic acids, polyols and others) by microbial fermentation of glycerol. Initially, the industrial use of each chemical is briefly presented; then we systematically summarize and discuss the different strategies to produce each chemical, including selection and genetic engineering of producers, and optimization of process conditions to improve yield and productivity. Finally, the impact of the developments obtained until now are placed in perspective and opportunities and challenges for using crude glycerol to the development of biodiesel-based biorefineries are considered. In conclusion, the microbial fermentation of glycerol represents a remarkable alternative to add value to the biodiesel production chain helping the development of biorefineries, which will allow this biofuel to be more competitive.

Genetic transformation of Diaporthe phaseolorum, an endophytic fungus found in mangrove forests, mediated by Agrobacterium tumefaciens.

We describe the genetic transformation of the mycelial tissue of Diaporthe phaseolorum, an endophytic fungus isolated from the mangrove species Laguncularia racemosa, using Agrobacterium tumefaciens-mediated transformation (ATMT). ATMT uses both the hygromycin B resistant (hph) gene and green fluorescent protein as the selection agents. The T-DNA integration into the fungal genome was assessed by both PCR and Southern blotting. All transformants examined were mitotically stable. An analysis of the T-DNA flanking sequences by thermal asymmetric interlaced PCR (TAIL-PCR) demonstrated that the disrupted genes in the transformants had similarities with conserved domains in proteins involved in antibiotic biosynthesis pathways. A library of 520 transformants was generated, and 31 of these transformants had no antibiotic activity against Staphylococcus aureus, an important human pathogen. The protocol described here, using ATMT in D. phaseolorum, will be useful for the identification and analysis of fungal genes controlling pathogenicity and antibiotic pathways. Moreover, this protocol may be used as a reference for other species in the Diaporthe genus. This is the first report to describe Agrobacterium-mediated transformation of D. phaseolorum as a tool for insertional mutagenesis.

Antimutagenic action of Lentinula edodes and Agaricus blazei on Aspergillus nidulans conidia

O efeito antimutagênico dos cogumelos Lentinula edodes e Agaricus blazei foram estudados sobre conídios de Aspergillus nidulans quando expostos à luz ultravioleta de comprimento de onda curto. Duas linhagens de A. nidulans foram usadas. Para o preparo dos extratos, os cogumelos frescos permaneceram em infusão aquosa por 12 horas e em seguida foram aquecidos em banho-maria por 15 min à 100ºC e a seguir o material foi filtrado. Os cogumelos desidratados foram deixados em infusão aquosa por 12 horas e a seguir filtrados. Ambos os filtrados foram usados como extratos. Os conídios de A. nidulans foram incubados por três horas em água e em extrato de cogumelo e somente após foram expostos a luz ultravioleta (pré-tratamento). Conídios de A. nidulans foram incubados em água e em extrato de cogumelo e imediatamente submetidos à luz ultravioleta (pós-tratamento). Conídios incubados em água e em extrato de cogumelo, mas sem exposição ao agente mutagênico, foram usados como controle. Após tratamento mutagênico, observou-se um aumento na taxa de sobrevivência de A. nidulans e uma diminuição na porcentagem de mutantes morfológicos em conídios tratados com extrato de cogumelos. Nossos resultados demonstram o efeito radioprotetor e antimutagênico dos cogumelos L. edodes e A. blazei sobre células eucarióticas submetidas à radiação UV.