The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of the 14,165 open reading frames identified. A detailed description of the components of the protein secretion pathway was made and striking differences in the hydrolytic enzyme spectra of aspergilli were observed. A reconstructed metabolic network comprising 1,069 unique reactions illustrates the versatile metabolism of A. niger. Noteworthy is the large number of major facilitator superfamily transporters and fungal zinc binuclear cluster transcription factors, and the presence of putative gene clusters for fumonisin and ochratoxin A synthesis.
Gene flow within populations can occur by sexual and/or parasexual means.
Analyses of experimental and in silico work are presented relevant to
possible gene flow within the aspergilli. First, the discovery of mating-type
(MAT) genes within certain species of Aspergillus is
described. The implications for self-fertility, sexuality in supposedly
asexual species and possible uses as phylogenetic markers are discussed.
Second, the results of data mining for heterokaryon incompatibility
(het) and programmed cell death (PCD) related genes in the genomes of
two heterokaryon incompatible isolates of the asexual species Aspergillus
niger are reported. Het-genes regulate the formation of
anastomoses and heterokaryons, may protect resources and prevent the spread of
infectious genetic elements. Depending on the het locus involved,
hetero-allelism is not tolerated and fusion of genetically different
individuals leads to growth inhibition or cell death. The high natural level
of heterokaryon incompatibility in A. niger blocks parasexual
analysis of the het-genes involved, but in silico
experiments in the sequenced genomes allow us to identify putative
het-genes. Homologous sequences to known het- and PCD-genes
were compared between different sexual and asexual species including different
Aspergillus species, Sordariales and the yeast
Saccharomyces cerevisiae. Both het- and PCD-genes were well
conserved in A. niger. However some point mutations and other small
differences between the het-genes in the two A. niger
isolates examined may hint to functions in heterokaryon incompatibility
reactions.
This paper reports on the identification and in vitro characterization of several Trichoderma strains isolated from the Tokaj Wine Region in North-East Hungary. Ten isolates were analyzed and found to consist of six individual species—T. gamsii, T. orientale, T. simmonsii, T. afroharzianum, T. atrobrunneum and T. harzianum sensu stricto. The growth potential of the strains was assessed at a range of temperatures. We also report here on the in vitro biocontrol properties and fungicide tolerance of the most promising strains.
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