School of Agricultural and Veterinarian Sciences, São Paulo State University (UNESP), Jaboticabal, SP, Brazil.
Department of Technology, Laboratory of Biochemistry and Plant Microorganisms, Jaboticabal, São Paulo, Brazil.
PLoS One. 2021 Mar 17;16(3):e0247822. doi: 10.1371/journal.pone.0247822. eCollection 2021.
After being isolated from a sugarcane pile, the bacterium Chitinophaga sp. CB10 demonstrated to be a rich source of carbohydrases, with 350 predicted CAZyme domains. CB10 was able to grow on carbohydrates of different structural complexities: glucose, carboxymethylcellulose, corn starch, galactomannan, Aloe vera gum and sugarcane bagasse. The sugarcane bagasse is a rich source of complex polymers, and the diversity of metabolites released by its enzymatic hydrolysis has an important role for green chemistry, including minority pathways such as the degradation of mannan conjugates. In this sense, CB10 demonstrated considerable levels of gene expression for mannanases, and was stable for a period of 96-144 hours in the presence of sugarcane bagasse as sole carbon source. The bacterium showed respectively 4.8x and 5.6x expression levels for two genes predicted for GH2 β-mannosidase: one located within a gene cluster identified as "polysaccharide utilization loci" (PUL), and another a classic β-mannosidase. These enzymes shared less than 45% of identity with enzymes characterized from the genus Chitinophaga belonging to the phylum Bacteroidetes. The degree of novelty-as demonstrated by the low identity with previously characterized enzymes; the remarkable capability to grow in different substrates; mannanase activity, evidenced by the release of residual oligosaccharides in the cultivation with galactomannan (HPLC-RID, 12.3 mMol); associated to the ability of mannanases expression in a low concentration of inductor conditions (sugarcane bagasse, 0.2%) indicate the high potential for the application of CB10 as a source of enzymes in the production of oligosaccharides from biomass. This capacity might prove to be very valuable for the biorefinery process of pre-biotic precursors and other functional oligosaccharides focused on the food and pharmaceutical industries.
从甘蔗堆中分离出来的噬几丁质菌（Chitinophaga sp. CB10）是碳水化合物酶的丰富来源，拥有 350 个预测的 CAZyme 结构域。CB10 能够在不同结构复杂性的碳水化合物上生长：葡萄糖、羧甲基纤维素、玉米淀粉、半乳甘露聚糖、库拉索芦荟胶和甘蔗渣。甘蔗渣是复杂聚合物的丰富来源，其酶解释放的代谢物多样性对绿色化学具有重要作用，包括甘露聚糖缀合物降解等少数途径。在这种情况下，CB10 展示了相当水平的甘露聚糖酶基因表达，并在以甘蔗渣为唯一碳源的情况下保持稳定 96-144 小时。该细菌分别对两个预测的 GH2 β-甘露糖苷酶基因表现出 4.8x 和 5.6x 的表达水平：一个位于被鉴定为“多糖利用基因座”（PUL）的基因簇内，另一个是经典的β-甘露糖苷酶。这些酶与属于拟杆菌门的噬几丁质属中已鉴定的酶的相似度均低于 45%。这种新颖性程度-通过与先前鉴定的酶的低相似度来证明；在不同底物中生长的卓越能力；甘露聚糖酶活性，在半乳甘露聚糖培养中通过释放残留的寡糖来证明（HPLC-RID，12.3 mMol）；与在低浓度诱导条件下（甘蔗渣，0.2%）表达甘露聚糖酶的能力相关，表明 CB10 作为酶的来源在从生物质生产寡糖方面具有很高的应用潜力。这种能力对于前生物前体和其他针对食品和制药行业的功能性寡糖的生物炼制过程可能非常有价值。
