Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil.
Fungal Genet Biol. 2013 Nov;60:19-28. doi: 10.1016/j.fgb.2013.07.003. Epub 2013 Jul 16.
This study investigated the yeast species associated with rotting wood in Brazilian Atlantic Rainforest ecosystems focusing on the identification of D-xylose-fermenting and/or xylanase-producing species. A total of 321 yeast strains were isolated from rotting wood samples collected in two Atlantic Rainforest areas. These samples were cultured in yeast nitrogen base (YNB)-D-xylose or YNB-xylan media. Schwanniomyces polymorphus, Scheffersomyces queiroziae, Barnettozyma californica, and Candida (Ogataea) boidinii were the most frequently isolated yeasts. The rarefaction curves for the yeast communities isolated in YNB-D-xylose and YNB-xylan from both areas continued to rise and did not reach an asymptote, indicating that not all yeast diversity had been recovered. Additionally, the yeast composition was variable among the samples and areas, which was confirmed by the values of the Sorensen index. Among the 69 species identified, only 12 were found in both areas sampled. Fifteen possible new species were obtained. Among them, two species (Sugiyamaella sp. 1 and Sugiyamaella xylanicola) showed the ability to ferment D-xylose into ethanol, and three species (Spencermartinsiella sp. 1, Su. xylanicola and Tremella sp.) were able to produce extracellular xylanases. Indeed, most of the xylanase-producing isolates belong to the new species Su. xylanicola, which was also positive for D-xylose fermentation. S.queiroziae and S. stipitis were the main D-xylose-fermenting yeasts identified. The results of this work showed that rotting wood collected from the Atlantic Rainforests is a huge source of yeasts, including new species, with promising biotechnological properties.
本研究调查了与巴西大西洋雨林生态系统中腐烂木材相关的酵母物种，重点是鉴定 D-木糖发酵和/或木聚糖酶产生的物种。从两个大西洋雨林地区采集的腐烂木材样本中分离出了 321 株酵母菌株。这些样品在酵母氮基（YNB）-D-木糖或 YNB-木聚糖培养基中培养。多形毕赤酵母、奎氏假丝酵母、加利福尼亚假丝酵母和卵形毕赤酵母是最常分离到的酵母。从两个地区的 YNB-D-木糖和 YNB-木聚糖中分离出的酵母群落的稀疏曲线继续上升，并未达到渐近线，表明尚未完全恢复所有酵母多样性。此外，酵母组成在不同的样品和地区之间存在差异，这一点通过索伦森指数的值得到了证实。在所鉴定的 69 个物种中，只有 12 个在两个采样地区都有发现。获得了 15 种可能的新物种。其中，有两种（杉山酵母 1 号和杉山木聚糖降解菌）具有将 D-木糖发酵成乙醇的能力，三种（Spencermartinsiella sp. 1、杉山木聚糖降解菌和银耳属）能够产生胞外木聚糖酶。事实上，大多数产木聚糖酶的分离株属于新种杉山木聚糖降解菌，该菌也能发酵 D-木糖。奎氏假丝酵母和酿酒酵母是鉴定出的主要 D-木糖发酵酵母。本研究结果表明，从大西洋雨林中采集的腐烂木材是酵母的巨大来源，包括具有有前景的生物技术特性的新物种。
