Abstract: Aureobasidium is omnipresent and can be isolated from air, water bodies, soil, wood, and other plant materials, as well as inorganic materials such as rocks and marble. A total of 32 species of this fungal genus have been identified at the level of DNA, of which Aureobasidium pullulans is best known. Aureobasidium is of interest for a sustainable economy because it can be used to produce a wide variety of compounds, including enzymes, polysaccharides, and biosurfactants. Moreover, it can be used to promote plant growth and protect wood and crops. To this end, Aureobasidium cells adhere to wood or plants by producing extracellular polysaccharides, thereby forming a biofilm. This biofilm provides a sustainable alternative to petrol-based coatings and toxic chemicals. This and the fact that Aureobasidium biofilms have the potential of self-repair make them a potential engineered living material avant la lettre. Key points: •Aureobasidium produces products of interest to the industry •Aureobasidium can stimulate plant growth and protect crops •Biofinish of A. pullulans is a sustainable alternative to petrol-based coatings •Aureobasidium biofilms have the potential to function as engineered living materials.
DOCUMENT
Dark homogenous fungal-based layers called biofinishes and vegetable oils are keyingredients of an innovative wood protecting system. The aim of this study was todetermine which of the vegetable oils that have been used to generate biofinishes onwood will provide carbon and energy for the biofinish-inhabiting fungus Aureobasidiummelanogenum, and to determine the effect of the oil type and the amount of oil on thecell yield. Aureobasidium melanogenum was cultivated in shake flasks with differenttypes and amounts of carbon-based nutrients. Oil-related total cell and colony-formingunit growth were demonstrated in suspensions with initially 1% raw linseed,stand linseed, and olive oil. Oil-related cell growth was also demonstrated with rawlinseed oil, using an initial amount of 0.02% and an oil addition during cultivation. Nilered staining showed the accumulation of fatty acids inside cells grown in the presenceof oil. In conclusion, each tested vegetable oil was used as carbon and energysource by A. melanogenum. The results indicated that stand linseed oil provides lesscarbon and energy than olive and raw linseed oil. This research is a fundamental stepin unraveling the effects of vegetable oils on biofinish formation.
MULTIFILE
Using an optimized transformation protocol we have studied the possible interactions between transforming plasmid DNA and the Hansenula polymorpha genome. Plasmids consisting only of a pBR322 replicon, an antibiotic resistance marker for Escherichia coli and the Saccharomyces cerevisiae LEU2 gene were shown to replicate autonomously in the yeast at an approximate copy number of 6 (copies per genome equivalent). This autonomous behaviour is probably due to an H. polymorpha replicon-like sequence present on the S. cerevisiae LEU2 gene fragment. Plasmids replicated as multimers consisting of monomers connected in a head-to-tail configuration. Two out of nine transformants analysed appeared to contain plasmid multimers in which one of the monomers contained a deletion. Plasmids containing internal or flanking regions of the genomic alcohol oxidase gene were shown to integrate by homologous single or double cross-over recombination. Both single- and multi-copy (two or three) tandem integrations were observed. Targeted integration occurred in 1-22% of the cases and was only observed with plasmids linearized within the genomic sequences, indicating that homologous linear ends are recombinogenic in H. polymorpha. In the cases in which no targeted integration occurred, double-strand breaks were efficiently repaired in a homology-independent way. Repair of double-strand breaks was precise in 50-68% of the cases. Linearization within homologous as well as nonhomologous plasmid regions stimulated transformation frequencies up to 15-fold.
DOCUMENT
