Novakomyces olei Dlauchy, Péter & Cˇ adež sp. nov.
MycoBank number: MB 838647; Index Fungorum number: IF 838647; Facesoffungi number: FoF;
Novakomyces olei (o.le’i. L. gen. neutr. sing. n. oleum,-i, olive oil, referring to its origin).
After 3 days of incubation at 25 ◦C in 5% malt extract, sediment is present, pellicle is not formed. Cells are subspheroid to ellipsoid, sometimes with one pointed end. They occur singly or in pairs and measure 2.0–5.0 × 2.5–6.0 µm. Asexual reproduction proceeds by multilateral budding, but the majority of the buds occupy polar position. On 5% malt extract agar after 3 days at 25 ◦C, the streak culture is butyrous, semi-glistening, smooth and flat, and white to cream coloured. The margin is entire. On slide culture with corn meal agar after 7 days at 25 ◦C, neither pseudohyphae nor septate hyphae are formed. Ascospore formation is preceded by parent cell–bud conjugation or cells are transformed to asci with- out conjugation and one or two easily liberating subspheroid or ellipsoid ascospores are formed in each ascus (Figure 5). Extremely scattered ascosporulation was observed in cultures grown on PDA following at least 50 days of incubation at 15 ◦C. The presence of heterogamous conjugation suggests that the species is homothallic. Fermentation is absent. The carbon compounds assimilated are D-glucose (variable), sucrose (variable), raffinose, melibiose (variable), D-galactose (positive or slow), α,α-trehalose (variable), maltose (variable), methyl-α-D-glucoside (positive or latent), salicin (slow and variable), arbutin (slow and variable), L-sorbose (variable), D-xylose (variable), ethanol (variable), glycerol (variable), meso-erythritol (variable), xylitol, D-mannitol (positive or slow), D- glucitol (variable), myo-inositol (variable), succinate (latent and variable), citrate (variable), D-gluconate (variable), 2-keto-D-gluconate (variable), glucono-δ-lactone (variable) and N-acetyl-D-glucosamine (slow and variable), while no growth occurs on inulin, lactose, melezitose, starch, cellobiose, L-rhamnose, L-arabinose, D-arabinose, D-ribose, methanol, ribitol, galactitol, L-arabinitol, DL-lactate, D-glucuronate, D-galacturonate, saccharate, D-glucosamine, propane 1,2 diol, butane 2,3 diol, and hexadecane. Ethylamine hydrochlo- ride, L-lysine, and creatine (variable) are assimilated; potassium nitrate, sodium nitrite, cadaverine dihydrochloride, creatinine, glucosamine (as nitrogen source), and imidazole are not assimilated.
Amyloid material is formed. Growth in vitamin-free medium is absent. Growth occurs at 30 ◦C and is absent at 35 ◦C. Growth with 0.01% cycloheximide and with 10% NaCl is absent. Weak growth occurs on 50% w/w glucose yeast extract agar but is absent with 60% w/w glucose yeast extract agar and with 1% acetic acid. No acid is produced on chalk agar. Urea is hydrolysed but colour reaction with Diazonium Blue B is negative. The major ubiquinone is Q-10.
Holotype: NCAIM Y.02187 deposited in the National Collection of Agricultural and Industrial Microorganisms, Budapest, Hungary; isotypes: CBS 16559 deposited in the Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands; ZIM 3702 deposited in Culture Collection of Industrial Microorganisms, Ljubljana, Slovenia. All are permanently preserved in a metabolically inactive state. The type culture was isolated from olive oil from Spain, in 2013.
The BioProject number for raw genome sequencing reads is PRJNA561902 (BioSample SAMN14856565), and the GenBank accession number for the assembled genome is JADEYG000000000.
Figure 5. Ascosporulating culture of Novakomyces olei NCAIM Y.02187T. One two-spored ascus is shown in each panel. In panel (A), the remnant of an ascus formed by the conjugation of the mother cell and its bud is indicated by arrow. Bar, 10 µm for both panels (A,B).