Pichia phaffii H. Y. Zhu, L. C. Guo, F. Y. Bai & P. J. Han, 2025

Pichia phaffii H. Y. Zhu, L. C. Guo, F. Y. Bai & P. J. Han sp. nov.

Etymology.

This species phaffii (phaf’fi. i. N. L. gen. n.) is named in honor of the late Prof. Herman Phaff for his significant contributions to the field of microbiology, particularly in yeast systematics and ecology.

Type.

The holotype CGMCC 2.8239 (original number = 25 - MEA- 424-1) was isolated from mudflat soil sediment collected from Dongguan city , Guangdong province, China (23.042 ° N, 113.743 ° E; subtropical monsoon climate) by H. Y. Zhu in July 2022 and had been deposited in a metabolically inactive state in the China General Microbiological Culture Collection Centre ( CGMCC), Beijing, China GoogleMaps . GenBank accessions: ITS - PQ 586092 and LSU - PQ 586298.

Culture characteristics.

After growth on YPD agar for 3 days at 25 ° C, colonies are white butyrous, rough and wrinkled with irregular surfaces and margins (Fig. 2 A View Figure 2 ). Cells are ovoid to elongate (2.1–3.2 × 3.3–7.1 μm) and occur singly or in pairs (Fig. 2 B View Figure 2 ). Budding is multilateral and pseudohyphae are formed (Fig. 2 D View Figure 2 ). Asci (2.8–3.5 × 6.2–7.1 μm) are persistent and unconjugated, typically forming two to four spherical spores within diamond-shaped ascus ascospores, although a linear arrangement of ascospores is seen as well (Fig. 2 C View Figure 2 ). The sexual structures were observed on YCB agar after 30 days at 25 ° C.

Physiological and biochemical characteristics.

Glucose is not fermented. Glucose, ethanol, erythritol (weak), succinic acid, sodium citrate dihydrate (weak), D-glucosamine, inulin (weak) and DL-lactic acid are assimilated as sole carbon sources. D-galactose, L-sorbose, D-xylose, glycerol, glucitol, sucrose, maltose, cellobiose, trehalose, lactose, melibiose, raffinose, melezitose, soluble starch, N-acetyl-D-glucosamine, L-arabinose, D-arabinose, xylitol, D-ribose, L-rhamnose, methanol, ribitol, galactitol, D-mannitol, α-methyl-D-glucoside, salicin, D-glucuronic acid, citrate acid, inositol and hexadecane are not assimilated as sole carbon sources. Ethylamine hydrochloride, cadaverine dihydrochloride, L-lysine, and ammonium sulfate are assimilated as sole nitrogen sources. Potassium nitrate and sodium nitrite are not assimilated as sole nitrogen sources. Growth in vitamin-free medium and on 50 % (w / v) glucose are positive, while growth in 10 % NaCl plus 5 % glucose medium and on 60 % (w / v) glucose is negative. Diazonium blue B, urease activity and production of extracellular starch-like compounds are negative. Growth on YPD agar at 30 ° C is positive, but negative at 37 ° C.

Notes.

Pichia phaffii sp. nov. is physiologically differentiated from its closely related species Pichia tetrigidarum comb. nov. in that Pichia tetrigidarum comb. nov. can ferment D-glucose, D-galactose, sucrose, maltose, trehalose, while Pichia phaffii sp. nov. does not.