BackgroundPlant biomass is the major substrate for the production of biofuels and biochemicals, as well as food, textiles and other products. It is also the major carbon source for many fungi and enzymes of these fungi are essential for the depolymerization of plant polysaccharides in industrial processes. This is a highly complex process that involves a large number of extracellular enzymes as well as non-hydrolytic proteins, whose production in fungi is controlled by a set of transcriptional regulators. Aspergillus species form one of the best studied fungal genera in this field, and several species are used for the production of commercial enzyme cocktails.ResultsIt is often assumed that related fungi use similar enzymatic approaches to degrade plant polysaccharides. In this study we have compared the genomic content and the enzymes produced by eight Aspergilli for the degradation of plant biomass. All tested Aspergilli have a similar genomic potential to degrade plant biomass, with the exception of A. clavatus that has a strongly reduced pectinolytic ability. Despite this similar genomic potential their approaches to degrade plant biomass differ markedly in the overall activities as well as the specific enzymes they employ. While many of the genes have orthologs in (nearly) all tested species, only very few of the corresponding enzymes are produced by all species during growth on wheat bran or sugar beet pulp. In addition, significant differences were observed between the enzyme sets produced on these feedstocks, largely correlating with their polysaccharide composition.ConclusionsThese data demonstrate that Aspergillus species and possibly also other related fungi employ significantly different approaches to degrade plant biomass. This makes sense from an ecological perspective where mixed populations of fungi together degrade plant biomass. The results of this study indicate that combining the approaches from different species could result in improved enzyme mixtures for industrial applications, in particular saccharification of plant biomass for biofuel production. Such an approach may result in a much better improvement of saccharification efficiency than adding specific enzymes to the mixture of a single fungus, which is currently the most common approach used in biotechnology.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0285-0) contains supplementary material, which is available to authorized users.
Plant biomass is the most abundant and usable carbon source for many fungal species. Due to its diverse and complex structure, fungi need to produce a large range of enzymes to degrade these polysaccharides into monomeric components. The fine-tuned production of such diverse enzyme sets requires control through a set of transcriptional regulators. Aspergillus has a strong potential for degrading biomass, thus this genus has become the most widely studied group of filamentous fungi in this area. This review examines Aspergillus as a successful degrader of plant polysaccharides, and reviews its potential in many industries such as biofuel and as a production host of homologous and heterologous proteins.
Genome sequencing has affected studies into the biology of all classes of organisms and this is certainly true for filamentous fungi. The level with which biological systems can be studied since the availability of genomes and post-genomic technologies is beyond what most people could have imagined previously. The fungal genera Aspergillus and Penicillium contain some species that are amongst the most widely used industrial microorganisms and others that are serious pathogens of plants, animals and humans. These genera are also at the forefront of fungal genomics with many genome sequences available and a whole genus genome sequencing project in progress for Aspergillus.This book highlights some of the changes in the studies into these fungi, since the availability of genome sequences. The contributions vary from insights in the taxonomy of these genera, use of genomics for forward genetics and genomic adaptations, to specific stories addressing virulence, carbon starvation, sulphur metabolism, feruloyl esterases, secondary metabolism and pH modulation, to the development of novel methodology for use in parallel to genome sequencing. It therefore provides a taste of the current status of research in Penicillium and Aspergillus and a promise of many more things to come.An essential reference for everyone working with Aspergillus and Penicillium and other filamentous fungi and the book is also recommended reading for everyone with an interest in fungal genomics.
demonstrated interesting differences in temperate optima, pH stability and substrate specificities. The endo-1,4-β-dglucanase from A. vadensis exhibited a pH and temperature optimum of pH 4.5 and 50 °C, respectively. Comparative biochemical analysis to the orthologous EglA from A. niger presented similar pH and substrate specificity profiles. However, significant differences in temperature optima and stability were noted.
The cover image is based on the Research Article A novel enzymatic method for the measurement of lactose in lactose‐free products by David Mangan et al., DOI: https://doi.org/10.1002/jsfa.9317. This cover was supported by Megazyme.
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