Bruni Gillian O, Qi Yunci, Terrell Evan, Dupre Rebecca A, Mattison Christopher P
U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA 70124, USA.
U.S. Department of Energy, Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA.
Microorganisms. 2024 Jan 5;12(1):107. doi: 10.3390/microorganisms12010107.
During raw sugarcane processing, a significant portion of lost sucrose is attributable to microbial degradation. Sucrose consumption by many bacteria is also linked to the production of exopolysaccharides (EPS) such as dextrans and fructans. These resulting EPS cause operational challenges during raw sugar manufacturing. Here, we report the characterization of EPS from a fructan-forming bacterium that we previously isolated from a Louisiana sugarcane factory. The genome sequencing revealed the presence of two encoded levansucrase genes, and . One levansucrase, LsrB, was detected in the secreted protein fraction of LASM12 by QTOF LC-MS. The spotting assays indicated that produces EPS using sucrose and raffinose as substrates. The EPS correlated with levan fructan commercial standards by H-NMR, and with the characteristic carbohydrate fingerprint region for FTIR spectra, confirming that the EPS is levan fructan. The glycosyl composition and glycosyl linkage analysis revealed a linear β-2,6-fructofuranosyl polysaccharide with occasional (5.7%) β-2,1-fructofuranosyl branches. The gel permeation chromatography of the levan fructan EPS showed two main peaks at 4.5 kDa and 8 kDa and a very minor peak at 500 kDa. was identified as a producer of levan fructan. These findings will be useful for future studies aimed at evaluating the impact of levan fructans on sugar crop processing, which have been historically underestimated in industry.
在原甘蔗加工过程中，大量损失的蔗糖可归因于微生物降解。许多细菌消耗蔗糖也与胞外多糖（EPS）如葡聚糖和果聚糖的产生有关。这些产生的EPS在原糖制造过程中带来了操作挑战。在此，我们报告了从路易斯安那州甘蔗工厂分离出的一种形成果聚糖的细菌所产生的EPS的特性。基因组测序显示存在两个编码的果聚糖蔗糖酶基因，即 和 。通过QTOF LC-MS在LASM12的分泌蛋白组分中检测到一种果聚糖蔗糖酶LsrB。点滴试验表明， 以蔗糖和棉子糖为底物产生EPS。通过H-NMR，该EPS与果聚糖商业标准品相关，并且与FTIR光谱的特征碳水化合物指纹区域相关，证实该EPS是果聚糖。糖基组成和糖基连接分析显示为线性β-2,6-呋喃果糖基多糖，偶尔有（5.7%）β-2,1-呋喃果糖基分支。果聚糖EPS的凝胶渗透色谱显示在4.5 kDa和8 kDa处有两个主峰，在500 kDa处有一个非常小的峰。 被鉴定为果聚糖的生产者。这些发现将有助于未来旨在评估果聚糖对糖料作物加工影响的研究，而在该行业中，果聚糖的影响在历史上一直被低估。
