42 research outputs found
Genetic Diversity, Recombination, and Divergence in Animal Associated Penicillium dipodomyis
Penicillium dipodomyis is thought to be an exclusively asexual fungus associated with Kangaroo Rats, Dipodomys species, and is unique among Penicillium species in growing at 37°C but producing no known toxins. Lack of recombination within P. dipodomyis would result in limited adaptive flexibility but possibly enhance local adaptation and host selection via maintenance of favourable genotypes. Here, analysis of DNA sequence data from five protein-coding genes shows that recombination occurs within P. dipodomyis on a small spatial scale. Furthermore, detection of mating-type alleles supports outcrossing and a sexual cycle in P. dipodomyis. P. dipodomyis was a weaker competitor in in vitro assays with other Penicillium species found in association with Kanagaroo rats. Bayesian species level analysis suggests that the P. dipodomyis lineage diverged from closely related species also found in cheek pouches of Kangaroo Rats and their stored seeds about 11 million years ago, a similar divergence time as Dipodomys from its sister rodent taxa
Biochemical mutagens affect the preservation of fungi and biodiversity estimations
Many fungi have significant industrial applications
or biosafety concerns and maintaining the original
characteristics is essential. The preserved fungi have to
represent the situation in nature for posterity, biodiversity
estimations, and taxonomic research. However, spontaneous
fungal mutations and secondary metabolites affecting
producing fungi are well known. There is increasing
interest in the preservation of microbes in Biological
Resource Centers (BRC) to ensure that the organisms
remain viable and stable genetically. It would be anathema
if they contacted mutagens routinely. However, for
the purpose of this discussion, there are three potential
sources of biochemical mutagens when obtaining individual
fungi from the environment: (a) mixtures of microorganisms
are plated routinely onto growth media
containing mutagenic antibiotics to control overgrowth
by contaminants, (b) the microbial mixtures may contain
microorganisms capable of producing mutagenic secondary
metabolites, and (c) target fungi for isolation may
produce “self” mutagens in pure culture. The probability
that these compounds could interact with fungi undermines
confidence in the preservation process and the
potential effects of these biochemical mutagens are considered
for the first time on strains held in BRC in this
review
Antifungal Activity of Microbial Secondary Metabolites
Secondary metabolites are well known for their ability to impede other microorganisms. Reanalysis of a screen of natural products using the Caenorhabditis elegans-Candida albicans infection model identified twelve microbial secondary metabolites capable of conferring an increase in survival to infected nematodes. In this screen, the two compound treatments conferring the highest survival rates were members of the epipolythiodioxopiperazine (ETP) family of fungal secondary metabolites, acetylgliotoxin and a derivative of hyalodendrin. The abundance of fungal secondary metabolites indentified in this screen prompted further studies investigating the interaction between opportunistic pathogenic fungi and Aspergillus fumigatus, because of the ability of the fungus to produce a plethora of secondary metabolites, including the well studied ETP gliotoxin. We found that cell-free supernatant of A. fumigatus was able to inhibit the growth of Candida albicans through the production of a secreted product. Comparative studies between a wild-type and an A. fumigatus ΔgliP strain unable to synthesize gliotoxin demonstrate that this secondary metabolite is the major factor responsible for the inhibition. Although toxic to organisms, gliotoxin conferred an increase in survival to C. albicans-infected C. elegans in a dose dependent manner. As A. fumigatus produces gliotoxin in vivo, we propose that in addition to being a virulence factor, gliotoxin may also provide an advantage to A. fumigatus when infecting a host that harbors other opportunistic fungi