Over 90 years have passed since Alexander Fleming's discovery of penicillin, the first recognized, naturally occurring antibiotic. Penicillin is a representative of a group of metabolites produced by large multienzyme complexes [nonribosomal peptide synthetases (NRPSs)] in a ribosome-independent fashion. Nonribosomal peptides (NRPs) are structurally diverse metabolites produced almost exclusively by bacteria and fungi. NRPs include bioactive compounds useful for pharmaceutical applications (e.g., antibiotics, antitumor compounds, and immunosuppressants) and therefore much progress has been made in our understanding of medically relevant characteristics of NRPs in the past decades. Natural roles of NRP metabolites, on the other hand, have been largely ignored, and much less is known about the biological/physiological significance of NRPs under natural settings. In the present review, we summarize past and current work on natural functions of NRPs in their fungal producers, with a focus on virulence, development, and stress tolerance, and highlight the diverse roles these small peptide metabolites play. Some NRPs are involved in interactions with host organisms, others work in fungus-environment interfaces, and still others are crucial for vegetative and reproductive development of the producing fungi.
A new species is described in the Mucorales family Syncephalastraceae: Syncephalastrum contaminatum, isolated as an in vitro culture from a laboratory contaminant. The species has variable copies of the internal transcribed spacer (ITS) regions, requiring cloning of these regions prior to Sanger sequencing before subsequent use in phylogenetic comparisons with other fungi. The genome of the strain was sequenced using short paired-reads to yield a draft genome of 28.6 Mb. Syncephalastrum contaminatum is distinguished by diverse DNA sequences at several loci from the other species of Syncephalastrum, including only 81% sequence identity with its ITS regions to that of S. racemosum. Its merosporangium produces four or more asexual spores and the genome sequencing information suggests that the species is heterothallic. The identification of this species highlights the limited knowledge about the early lineages of fungi both in Australia and globally.
Five Simplicillium isolates were obtained from foam generated in an aquarium in Minato-ku, Tokyo, Japan. Using a combination of micro-morphological characteristics and multigene (ITS, SSU, LSU, TEF) phylogenics, the isolates were identified as S. subtropicum and a new species which were previously undescribed. Simplicillium spumae, which is a new species, differs from known Simplicillium species in the morphology of their conidia and conidiophores.
In Coprinus comatus, we sampled and observed different maturity stages of basidium to find the possible causes of binucleate basidiospores by microscopy using the HCI-Giemsa and DAPI staining methods. In basidium, following karyogamy, a single nucleolus was observed. We found evidence suggesting post-meiotic mitosis following nuclear migration in the spores. Post-meiotic mitosis occurred in the basidiospores, resulting in four binucleate basidiospores. This indicates that the basidiospore is a monokaryon, and that C. comatus shows the same pattern of basidiospore formation as Coprinopsis cinerea. This type of nuclear behavior was defined as pattern D, one of six distinct patterns (pattern A–F) of nuclear behavior during basidiosporogenesis have been described for basidiomycetes by Campos and Costa in 2010.
Alkaliphilic xylanase from Neosartorya spinosa UZ-2-11 was purified using a three-step of purification scheme of ammonium sulphate precipitation followed by Sephadex G-100 gel filtration and DEAE-cellulose ion-exchange chromatography, and compared its properties with N. tatenoi KKU-CLB-3-2-4-1 of our previous report. The purified xylanase from N. spinosa UZ-2-11 exhibited maximum activity at pH 9.0 and 45 °C which was similar to endo-xylanase from N. tatenoi KKU-CLB-3-2-4-1. However, this enzyme was stable in a range of pH 6.0–11.0. It was also more stable at a high temperature of 50 °C where the activity was still up to 50% after heating for 120 min. The xylanase was purified 7.89-fold with 3.0% of yield to obtain a specific activity of 11.88 U/mg. The molecular weight of xylanase from this fungus was 27.68 kDa. The Km and Vmax values of the purified xylanase were 0.24 mg/mL and 15.85 μmol/min/mg, respectively. The xylanase activity was moderately inhibited by Hg2+ at a concentration of 10 mM, which was different to the case of N. tatenoi KKU-CLB-3-2-4-1 where Hg2+ was a strong inhibitor. In addition, the hydrolysed birchwood xylan was obtained mailnly xylobiose, xylotriose, xylotetraose and xylopentaose as end products, suggesting that it was an endo-xylanase.
Biodiesel (fatty acids methyl esters, FAME) has attracted considerable attention as an environmentally and eco-friendly alternative for diesel engines. This research manipulates the use of Aspergillus whole-cell lipase as a biocatalyst for biodiesel production from waste frying oil (WFO). A total of 17 isolates of Aspergillus species screened for lipase and esterase production abilities. Qualitatively, 11 Aspergillus isolates showed lipase and/or esterase activities and only 4 isolates were able to perform WFO transesterification under the tested conditions. Two Aspergillus isolates showed relatively high FAME yields, thus were selected as good enzyme producers. These two isolates were molecularly identified using rRNA gene sequence ITS1 and ITS2 as A. tamarii NDA03a (Genbank Accession Number MK849615) and A. flavus NDA04a (Genbank Accession Number MK811208), respectively. These identified isolates were exposed to ethyl methanesulfonate (EMS) for producing hyper lipolysis mutants. Mutagenesis led to 13.15 and 14.45% improvement of the WFO transesterification by A. tamarii NDA03a and A. flavus NDA04a, respectively. Random amplified polymorphic DNA (RAPD) analysis of the produced mutants confirmed the genetic basis of the activity variation. Genetic polymorphism reached to 79.31% and 80.65% between A. flavus NDA04a and A. tamarii NDA03a mutants and their corresponding wild types, respectively.
A newly described species of Pithoascus from roots of Ferula ovina differs from other Pithoascus species by producing larger ascomata than all described species except P. exsertus. The shape of its ascospores is similar to that of P. lunatus, but differs from it by having an asexual state. This new species differs from P. ater by having a sexual state. Phylogenetic analyses based on concatenated ITS rDNA, LSU rDNA and partial translation elongation factor 1 alpha gene datasets also confirmed the generic placement in Pithoascus and showed its close phylogenetic relationships to P. ater and P. lunatus.