Chitin and chitosan from Basidiomycetes

Chitinous material was isolated from the mycelium of seven species of Basidiomycetes to evaluate the possibility of using fungal biomass as a source of chitin and chitosan. Such material was characterised for its purity, degree of acetylation and crystallinity. Chitin yields ranged between 8.5 and 19.6% dry weight and the chitosan yield was approximately 1%. The characteristics of the fungal chitins were similar to those of commercial chitin. Chitosans, with a low degree of acetylation, comparable with that of commercial chitosan, were obtained by the chemical deacetylation of fungal chitins.     

Principles from community and metapopulation ecology: application to fungal entomopathogens

Fungal entomopathogens are often studied within the context of their use for biological control, yet these natural enemies are also excellent subjects for studies of ecological interactions. Here, we present selected principles from community ecology and discuss these in relation to fungal entomopathogens. We discuss the relevance of apparent competition, food web construction, intraguild predation and density-mediated and trait-mediated indirect effects. Although current knowledge of community interactions involving fungal entomopathogens are limited, fungal entomopathogens can be important, interactive members of communities and the activities of fungal entomopathogens should be evaluated in the context of ecological principles. We also discuss aspects of metapopulation ecology and the application of these principles to fungal entomopathogens. Knowledge of ecological interactions is crucial if we are to understand and predict the effects of fungal entomopathogens on host populations and understand the interactions among fungal entomopathogens and other organisms in the communities in which they occur.     

Distinguishing plant and fungal sequences in ESTs from infected plant tissues

Expressed sequence tags (ESTs) from fungal-infected plant tissues are composed of a mixture of plant and fungal sequences. Using freely available software and tools, a novel procedure is described for distinguishing plant and fungal DNA sequences. Although the GenBank non-redundant (NR) database is larger and therefore one would presume that BLASTX analysis of it would be more accurate, superior resolution of 700 randomly selected fungal ESTs was found with Standalone TBLASTX analyses with a local matching database composed of a plant and a fungal genome. Standalone TBLASTX analyses of 3,983 ESTs from nine different fungal-infected plant EST libraries also proved to be superior in identifying the origin of sequences as either plant or fungal compared to GenBank BLASTX analysis. Standalone TBLASTX with a matching database comprised of a single plant and a single fungal genome appears to be a faster and more accurate method than BLASTX searches of the GenBank non-redundant database to distinguish fungal and plant sequences in mixed EST collections.     

Entomopathogenic fungi and insect behaviour: from unsuspecting hosts to targeted vectors

The behavioural response of an insect to a fungal pathogen will have a direct effect on the efficacy of the fungus as a biological control agent. In this paper we describe two processes that have a significant effect on the interactions between insects and entomopathogenic fungi: (a) the ability of target insects to detect and avoid fungal pathogens and (b) the transmission of fungal pathogens between host insects. The behavioural interactions between insects and entomopathogenic fungi are described for a variety of fungal pathogens ranging from commercially available bio-pesticides to non-formulated naturally occurring pathogens. The artificial manipulation of insect behaviour using dissemination devices to contaminate insects with entomopathogenic fungi is then described. The implications of insect behaviour on the use of fungal pathogens as biological control agents are discussed.     

Diversity and Antimicrobial Activity of Culturable Fungi Isolated from Six Species of the South China Sea Gorgonians

Fungi in gorgonians are now known to cause gorgonian diseases, but little attention has been paid to the nature of fungal communities associated with gorgonians. The diversity of culturable fungi associated with six species of healthy South China Sea gorgonians were investigated using a culture-dependent method followed by analysis of fungal internal transcribed spacer sequences. A total of 121 fungal isolates were recovered and identified using the Basic Local Alignment Search Tool search program. These belonged to 41 fungal species from 20 genera. Of these, 30 species and 12 genera are new reports for gorgonians, and the genera Aspergillus and Penicillium were the most diverse and common in the six gorgonian species. Comparison of the fungal communities in the six gorgonian species, together with results from previous relevant studies, indicated that different gorgonian species and the same gorgonian species living in different geographic locations had different fungal communities. The gorgonian Dichotella gemmacea harbored the most fungal species and isolates, while Echinogorgia aurantiaca had the least fungal diversity. Among the six media used for fungal isolation, potato glucose agar yielded the highest isolates (27 isolates), while glucose peptone starch agar had the best recoverability of fungal species (15 species). The antimicrobial activity of the 121 fungal isolates was tested against three marine bacteria and two marine gorgonian pathogenic fungi. A relatively high proportion (38?%) of fungal isolates displayed distinct antibacterial and antifungal activity, suggesting that the gorgonian-associated fungi may aid their hosts in protection against pathogens. This is the first report comparing the diversity of fungal communities among the South China Sea gorgonians. It contributes to our knowledge of gorgonian-associated fungi and further increases the pool of fungi available for natural bioactive product screening.     

Evidence from beta-tubulin phylogeny that microsporidia evolved from within the fungi

Microsporidia are obligate intracellular parasites that were thought to be an ancient eukaryotic lineage based on molecular phylogenies using ribosomal RNA and translation elongation factors. However, this ancient origin of microsporidia has been contested recently, as several other molecular phylogenies suggest that microsporidia are closely related to fungi. Most of the protein trees that place microsporidia with fungi are not well sampled, however, and it is impossible to resolve whether microsporidia evolved from a fungus or from a protistan relative of fungi. We have sequenced beta-tubulins from 3 microsporidia, 4 chytrid fungi, and 12 zygomycete fungi, expanding the representation of beta-tubulin to include all four fungal divisions and a wide diversity of microsporidia. In phylogenetic trees including these new sequences, the overall topology of the fungal beta-tubulins generally matched the expected relationships among the four fungal divisions, although the zygomycetes were polyphyletic in some analyses. The microsporidia consistently fell within this fungal diversification, and not as a sister group to fungi. Overall, beta-tubulin phylogeny suggests that microsporidia evolved from a fungus sometime after the divergence of chytrids. We also found that chytrid alpha- and beta-tubulins are much less divergent than are tubulins from other fungi or microsporidia. In trees in which the only fungal representatives were the chytrids, microsporidia still branched with fungi (i.e., with chytrids), suggesting that the affiliation between microsporidian and fungal tubulins is not an artifact of long-branch attraction.     

Succinic acid production from wheat using a biorefining strategy

The biosynthesis of succinic acid from wheat flour was investigated in a two-stage bio-process. In the first stage, wheat flour was converted into a generic microbial feedstock either by fungal fermentation alone or by combining fungal fermentation for enzyme and fungal bio-mass production with subsequent flour hydrolysis and fungal autolysis. In the second stage, the generic feedstock was converted into succinic acid by bacterial fermentation by Actinobacillus succinogenes. Direct fermentation of the generic feedstock produced by fungal fermentation alone resulted in a lower succinic acid production, probably due to the low glucose and nitrogen concentrations in the fungal broth filtrate. In the second feedstock production strategy, flour hydrolysis conducted by mixing fungal broth filtrate with wheat flour generated a glucose-rich stream, while the fungal bio-mass was subjected to autolysis for the production of a nutrient-rich stream. The possibility of replacing a commercial semi-defined medium by these two streams was investigated sequentially. A. succinogenes fermentation using only the wheat-derived feedstock resulted in a succinic acid concentration of almost 16 g l^–1 with an overall yield of 0.19 g succinic acid per g wheat flour. These results show that a wheat-based bio-refinery employing coupled fungal fermentation and subsequent flour hydrolysis and fungal autolysis can lead to a bacterial feedstock for the efficient production of succinic acid.     

Production of lactic acid and fungal biomass by Rhizopus fungi from food processing waste streams

This study proposed a novel waste utilization bioprocess for production of lactic acid and fungal biomass from waste streams by fungal species of Rhizopus arrhizus 36017 and R. oryzae 2062. The lactic acid and fungal biomass were produced in a single-stage simultaneous saccharification and fermentation process using potato, corn, wheat and pineapple waste streams as production media. R. arrhizus 36017 gave a high lactic acid yield up to 0.94-0.97 g/g of starch or sugars associated with 4-5 g/l of fungal biomass produced, while 17-19 g/l fungal biomass with a lactic acid yield of 0.65-0.76 g/g was produced by the R. oryzae 2062 in 36-48 h fermentation. Supplementation of 2 g/l of ammonium sulfate, yeast extract and peptone stimulated an increase in 8-15% lactic acid yield and 10-20% fungal biomass.     

Beta-amylases from various fungal strains. A review

An overview presentation is made on the current global status of fungal beta3-amylases, their characteristics and applications in various industries. Among the few available report on beta-amylase producing fungal strains, many showed a preference for a cultivation temperature of 28 degrees C, acidic pH and soluble starch as an inducer of enzyme synthesis. In some fungal strains, alpha-amylase and alpha-glucosidases were found to be present as major contaminating enzymes. Although the existence of a few starch digesting and raw starch adsorbing fungal strains were reported, detailed study on molecular biology of corresponding fungal genes was not available.     

A novel PCR-based approach for the detection and classification of potential cellulolytic fungal strains isolated from museum items and surrounding indoor environment

Aims: To develop a novel PCR‐based method able to detect potential cellulolytic filamentous fungi and to classify them exploiting the amplification of the cellobiohydrolase gene (cbh‐I) and its polymorphism. Methods and Results: A mixed approach including the combination of (i) fungal cultivation and isolation, (ii) classification of fungal isolates through the amplification of the cbh gene using a fluorescently labelled primer (f‐CBH‐PCR) and (iii) final fungal identification based on amplification and sequencing of the ITS1‐5.8S rDNA‐ITS2 region of the selected fungal strains was developed. By this approach, it was possible to screen 77 fungal strains belonging to 14 genera and 26 species. Conclusions: The f‐CBH‐PCR permitted the discrimination of fungal species, producing typical f‐CBH profiles. Significance and Impact of the Study: In this study, the cbh gene was used as a preliminary classification tool able to differentiate among themselves the fungal members isolated from indoor museum items and surrounding environment. Such mixed approach consented the fast identification of all isolated fungal strains. The f‐CBH‐PCR method demonstrated its discrimination power, and it can be considered as a new molecular system suitable for the classification of fungal strains isolated from different environments.     

烤后不同霉变程度烟叶际真菌群落组成与多样性分析

【目的】为了解烤后不同霉变程度烟叶真菌群落组成与多样性。【方法】基于IlluminaMiSeq高通量测序平台对烤后烟叶叶柄和叶片叶际样品的真菌群落组成进行了分析。【结果】霉变重烟叶叶片(BQ)、霉变重烟叶叶柄(BZ)、霉变轻烟叶叶片(JQ)、霉变轻烟叶叶柄(JZ) 4类样品真菌分布于子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、接合菌门(Zygomycota)等7个菌门、27个纲、58个目、104个科、171个属的360个真菌分类单元(OTUs)。不同霉变程度烟叶叶际真菌群落组成、分类单元的相对丰度及优势分类单元皆存在不同程度差异。在属的水平上,霉变重烟叶叶片(BQ)的优势菌属为Aspergillus (89.64%)、Myrothecium (2.54%)、Rhodotorula (2.48%)、Gibberella (1.49%);霉变重烟叶叶柄(BZ)的优势菌属为Aspergillus(96.93%)和Alternaria(1.92%);霉变轻烟叶叶片(JQ)的优势菌属为Aspergillus(40.13%)、Rhodotorula(31.81%)、Alternaria(16.75%);霉变轻烟叶叶柄(JZ)的优势菌属为Aspergillus (62.77%)、Alternaria (9.74%)、Rhodotorula (5.20%)。【结论】霉变轻烟叶叶片样品真菌群落的多样性最高,霉变轻烟叶叶柄的真菌群落丰富度最高。霉变重烟叶样品的叶片部位的真菌群落丰富度和多样性均高于叶柄。烟叶霉烂为烤房常见病害,其病原真菌种类多样,且广泛分布于烟叶和环境中。该研究结果为烤房烟叶霉烂病的防治可根据不同发病程度的不同部位的真菌群落构成特征,制定相应的防治方案提供了参考依据。     

Concurrent production of chitin from shrimp shells and fungi

Crustacean shells constitute the traditional and current commercial source of chitin. Conversely, the control of fungal fermentation processes to produce quality chitin makes fungal mycelia an attractive alternative source. Therefore, the exploitation of both of these sources to produce chitin in a concurrent process should be advantageous and is reported here. Three proteolytic Aspergillus niger (strains 0576, 0307 and 0474) were selected from a screening for protease activity from among 34 zygomycete and deuteromycete strains. When fungi and shrimp shell powder were combined in a single reactor, the release of protease by the fungi facilitated the deproteinization of shrimp-shell powder and the release of hydrolyzed proteins. The hydrolyzed proteins in turn were utilized as a nitrogen source for fungal growth, leading to a lowering of the pH of the fermentation medium, thereby further enhancing the demineralization of the shrimp-shell powder. The shrimp-shell powders and fungal mycelia were separated after fermentation and extracted for chitin with 5% LiCl/DMAc solvent. Chitin isolates from the shells were found to have a protein content of less than 5%, while chitin isolates from the three fungal mycelia strains had protein content in the range of 10-15%. The relative molecular weights as estimated by GPC for all chitin samples were in the 10(5) dalton range. All samples displayed characteristic profiles for chitin in their FTIR and solid-state NMR spectra. All chitin samples evaluated with MTT and Neutral Red assays with three commercial cell lines did not display cytotoxic effects.     

Molecular diversity of fungal phylotypes co-amplified alongside nematodes from coastal and deep-sea marine environments

Nematodes and fungi are both ubiquitous in marine environments, yet few studies have investigated relationships between these two groups. Microbial species share many well-documented interactions with both free-living and parasitic nematode species, and limited data from previous studies have suggested ecological associations between fungi and nematodes in benthic marine habitats. This study aimed to further document the taxonomy and distribution of fungal taxa often co-amplified from nematode specimens. A total of 15 fungal 18S rRNA phylotypes were isolated from nematode specimens representing both deep-sea and shallow water habitats; all fungal isolates displayed high pairwise sequence identities with published data in Genbank (99-100%) and unpublished high-throughput 454 environmental datasets (>95%). BLAST matches indicate marine fungal sequences amplified in this study broadly represent taxa within the phyla Ascomycota and Basidiomycota, and several phylotypes showed robust groupings with known taxa in phylogenetic topologies. In addition, some fungal phylotypes appeared to be present in disparate geographic habitats, suggesting cosmopolitan distributions or closely related species complexes in at least some marine fungi. The present study was only able to isolate fungal DNA from a restricted set of nematode taxa; further work is needed to fully investigate the taxonomic scope and function of nematode-fungal interactions.     

从麦草浆污泥中分离产木聚糖酶的木质纤维降解真菌

采用涂布平板法在马丁氏培养基平板上对麦草浆污泥作真菌分离研究,共分离纯化获得27株真菌,其中青霉属(Penicillium)、曲霉属(Aspergillus)、麦轴梗霉属(Tritirachium)根霉属(Rhizopus)和毛霉属(Mucor)为其优势菌群;在麦芽提取物-OPP培养基平板上分离得到10株真菌,其中拟指突孢曲霉属(Emercellopsis)为其优势菌群。通过对麦草浆污泥连续富集培养得到真菌10株,经初步鉴定为曲霉属(Aspergillus)和青霉属(Penicillium)。对富集培养分离的菌种进行木聚糖酶产酶特性研究,结果表明:最优菌株为Aspergillussp.MC-JAⅡ,其木聚糖酶酶活性最高值达到2060 U/mL,发生在产酶培养的第84 h,相应纤维素酶活为99.5 U/mL。为国内首次报道麦草浆污泥中的降解木质纤维真菌的分离、鉴定和产酶研究。     

Fungal diversity from communities to genes

Fungi are hyperdiverse organisms and assemble in complex communities, characterized by high levels of species richness, turnover, and endemism. However, the origins and maintenance of such high diversity and the role environments play in fungal adaptation are still elusive. Traditionally, efforts to understand fungal diversity in their environment have been divided between studies at the species level and below species level, with separate disciplines such as community ecology and population genetics working independently and with little communication. Here I argue that linking these different approaches is required to fully document the diversity of fungi in nature. Understanding the patterns and mechanisms of fungal diversity and composition requires not only the study of species assemblies and ranges, but also relies on comprehending fungal intra-specific variation, dispersal and establishment, including identifying key traits influencing fitness. This implies better integration and cross-fertilization between disciplines addressing fungi at a multitude of biological levels, ranging from genes to whole communities. Such approach will yield direct links between variation, adaptation and environments and provide a much more comprehensive understanding of fungal diversity.     

Efficacy of extraction methods for lipid and fatty acid composition from fungal cultures

The efficacy of three extraction methods for determining the lipid and fatty acid composition of six fungal cultures was studied. The extraction methods were: chloroform/methanol (2:1), hexane/isopropanol (3:2) and Soxhlet extraction by using hexane. The total lipid and fatty acid composition varied in fungal cultures depending on the extraction conditions. Of the three methods, chloroform/methanol (2:1) was found to be the best for extraction of lipid and fatty acids from fungal cultures.     

Production of lactic acid and fungal biomass by Rhizopus fungi from food processing waste streams

This study proposed a novel waste utilization bioprocess for production of lactic acid and fungal biomass from waste streams by fungal species of Rhizopus arrhizus 36017 and R. oryzae 2062. The lactic acid and fungal biomass were produced in a single-stage simultaneous saccharification and fermentation process using potato, corn, wheat and pineapple waste streams as production media. R. arrhizus 36017 gave a high lactic acid yield up to 0.94–0.97 g/g of starch or sugars associated with 4–5 g/l of fungal biomass produced, while 17–19 g/l fungal biomass with a lactic acid yield of 0.65–0.76 g/g was produced by the R. oryzae 2062 in 36–48 h fermentation. Supplementation of 2 g/l of ammonium sulfate, yeast extract and peptone stimulated an increase in 8–15% lactic acid yield and 10–20% fungal biomass.

     

Production of fungal protein and glucoamylase by Rhizopus oligosporus from starch processing wastewater

A simple, non-aseptic, low-cost single process had been developed for the treatment of starch processing wastewater (SPW) with the production of fungal protein and glucoamylase enzyme. The selected fungus Rhizopus oligosporus DAR 2710 has the ability to covert more than 95% starch materials in SPW to produce 4.5–5.2 g of dry fungal biomass from a litre of SPW in 14 h cultivation at 35°C and initial pH 4.0. The fungal biomass contained 46% protein and was safe for human and animal consumption. The process using an air lift bioreactor was successfully carried out in a batch system without sterilization and/or preliminary hydrolysis of SPW. In addition to the production of fungal protein and glucoamylase, the removal of 95% COD and total suspended solids would lead to a potential benefit to the environment.     

Taxol from fungal endophytes and the issue of biodiversity

Fungi represent one of the most understudied and diverse group of organisms. Commonly, these organisms make associations with higher life forms and may proceed to biochemically mimic the host organism. An excellent example of this is the anticancer drug, taxol, which had been previously supposed to occur only in the plant genusTaxus (yew). However, taxol has been reported in a novel endophytic fungus—Taxomyces andreanae, but also has been demonstrated to occur in a number of unrelated fungal endophytes includingPestalotia, Pestalotiopsis, Fusarium, Alternaria, Pithomyces, Monochaetia and others. Thus, this report presents information on the presence of taxol among disparate fungal genera, and uses these observations as an additional argument to support efforts to study fungal endophytes and preserve their associated host plants.     

Evolution and phylogenetic relationships of chitin synthases from yeasts and fungi

Chitin, the structural component that provides rigidity to the cell wall of fungi is the product of chitin synthases (Chs). These enzymes are not restricted to fungi, but are amply distributed in four of the five eukaryotic 'crown kingdoms'. Dendrograms obtained by multiple alignment of Chs revealed that fungal enzymes can be classified into two divisions that branch into at least five classes, independent of fungal divergence. In contrast, oomycetes and animals each possess a single family of Chs. These results suggest that Chs originated as a branch of beta-glycosyl-transferases, once the kingdom Plantae split from the evolutionary line of eukaryotes. The existence of a single class of Chs in animals and Stramenopiles, against the multiple families in fungi, reveals that Chs diversification occurred after fungi departed from these kingdoms, but before separation of fungal groups. Accordingly, each fungal taxon contains members with enzymes belonging to different divisions and classes. Multiple alignment revealed the conservation of specific motifs characteristic of class, division and kingdom, but the strict conservation of only three motifs QXXEY, EDRXL and QXRRW, and seven isolated amino acids in the core region of all Chs. Determination of different structural features in this region of Chs brought to light a noticeable conservation of secondary structure in the proteins.