Pichia kregeriana S. Hu, L. C. Guo, F. Y. Bai & P. J. Han, 2025

Guo, Liang-Chen, Hu, Shuang, Zhu, Hai-Yan, Shang, Yu-Jie, Qiu, Yan-Jie, Wen, Zhang, Chen, Shen-Xi, Bai, Feng-Yan & Han, Pei-Jie, 2025, Four new species of Pichia (Pichiales, Pichiaceae) isolated from China, MycoKeys 114, pp. 115-132 : 115-132

Pichia kregeriana S. Hu, L. C. Guo, F. Y. Bai & P. J. Han sp. nov.

Etymology.

The species kregeriana (kre. ge. ri. a’na. N. L. fem. adv.) is named in honor of the late Dr. Nelly Jeanne Wilhelmina Kreger-van Rij for her work in the field of microbiology, particularly in yeast systematics and ultrastructure.

Type.

The holotype CGMCC 2.7383 (original number = HWY 125-4) was isolated from rotten wood of Garcinia mangostana collected from Wuzhishan city , Hainan province, China (18.902 ° N, 109.688 ° E; tropical monsoon oceanic climate) by S. Hu in August, 2023 and had been deposited in a metabolically inactive state in the China General Microbiological Culture Collection Centre ( CGMCC), Beijing, China . An ex-type culture had been deposited in the Japan Collection of Microorganisms (JCM), Koyadai, Japan, as JCM 36906. GenBank accessions: ITS - PQ 586094 and LSU - PQ 586304.

Culture characteristics.

After growth on YPD agar for 3 days at 25 ° C, colonies are white, butyrous, nearly circular, lightly raised, rough and wrinkled with irregular surfaces and margins (Fig. 3 A ). Cells are oval-shaped or oval (3.3–4.5 × 4.9-8.7 μm) and budding is multilateral (Fig. 3 B ). No pseudohyphae are formed. Asci (2.4–4.6 × 5.0–5.4 um) are persistent and conjugated, typically forming two to four spherical spores within shuttle-shaped or triangular ascospores (Fig. 3 C ). The sexual structures were observed on YCB agar after 30 days at 25 ° C. Conjugation can occur between a cell and its bud, or between independent cells.

Physiological and biochemical characteristics.

Glucose is not fermented. Glucose, ethanol, N-acetyl-D-glucosamine, glycerol (slow), D-glucosamine (weak), inulin (weak), sucrose (weak) and succinic acid are assimilated as sole carbon sources. D-galactose, L-sorbose, erythritol, D-xylose, glucitol, D-maltose, sodium citrate dihydrate, cellobiose, trehalose, lactose, melibiose, raffinose, melezitose, soluble starch, L-arabinose, D-arabinose, xylitol, D-ribose, L-rhamnose, methanol, ribitol, galactitol, D-mannitol, α-methyl-D-glucoside, salicin, D-glucuronic acid, DL-lactic 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 are 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.

Note.

Pichia kregeriana is physiologically differentiated from its closely related species, Pichia kurtzmaniana , by fermentation of glucose, growth on 60 % (w / v) glucose and growth in 10 % NaCl plus 5 % glucose medium.

Figures

Figure 3. Morphology of Pichia phaffii strain 25 - MEA- 424-1 T. A Colony on YPD agar at 25 ° C after 3 days B vegetative cells on YPD agar at 25 ° C after 3 days C asci and ascospores on YCB agar at 25 ° C after 30 days D pseudohyphae on YPD agar at 25 ° C after 15 days. Scale bars: 10 µm.