Data_Sheet_1_Diversity of Marine 1,3-Xylan-Utilizing Bacteria and Characters of Their Extracellular 1,3-Xylanases.DOCX

1,3-xylan is present in the cell walls of some red and green algae and is an important organic carbon in the ocean. However, information on its bacterial degradation is quite limited. Here, after enrichment with 1,3-xylan, the diversity of bacteria recovered from marine algae collected in Hainan, China, was analyzed with both the 16S rRNA gene amplicon sequencing and the culture-dependent method. Bacteria recovered were affiliated with more than 19 families mainly in phyla Proteobacteria and Bacteroidetes, suggesting a high bacterial diversity. Moreover, 12 strains with high 1,3-xylanase-secreting ability from genera Vibrio, Neiella, Alteromonas, and Gilvimarinus were isolated from the enrichment culture. The extracellular 1,3-xylanases secreted by Vibrio sp. EA2, Neiella sp. GA3, Alteromonas sp. CA13-2, and Gilvimarinus sp. HA3-2, which were taken as representatives due to their efficient utilization of 1,3-xylan for growth, were further characterized. The extracellular 1,3-xylanases secreted by these strains showed the highest activity at pH 6.0–7.0 and 30–40°C in 0–0.5M NaCl, exhibiting thermo-unstable and alkali-resistant characters. Their degradation products on 1,3-xylan were mainly 1,3-xylobiose and 1,3-xylotriose. This study reveals the diversity of marine bacteria involved in the degradation and utilization of 1,3-xylan, helpful in our understanding of the recycling of 1,3-xylan driven by bacteria in the ocean and the discovery of novel 1,3-xylanases.

1,3-木聚糖（1,3-xylan）存在于部分红藻和绿藻的细胞壁中，是海洋中重要的有机碳组分。然而，目前关于其细菌降解的相关研究报道仍较为匮乏。本研究以中国海南采集的海洋海藻为样本，经1,3-木聚糖富集培养后，分别采用16S rRNA基因扩增子测序与可培养方法，对所获得的细菌多样性进行分析。所回收的细菌分属于超过19个科，主要隶属于变形菌门（Proteobacteria）与拟杆菌门（Bacteroidetes），表明该样本中细菌多样性较高。此外，本研究从富集培养物中分离得到12株可高效分泌1,3-木聚糖酶的菌株，分属于弧菌属（Vibrio）、Neiella属、交替单胞菌属（Alteromonas）以及Gilvimarinus属。选取因能高效利用1,3-木聚糖进行生长的代表菌株：弧菌属sp. EA2、Neiella属sp. GA3、交替单胞菌属sp. CA13-2以及Gilvimarinus属sp. HA3-2，对其分泌的胞外1,3-木聚糖酶进行了进一步的酶学特性表征。上述菌株分泌的胞外1,3-木聚糖酶在pH 6.0~7.0、温度30~40℃、NaCl浓度0~0.5M的条件下酶活性最高，表现出热不稳定性与耐碱性的特性。该类酶对1,3-木聚糖的降解产物主要为1,3-木二糖与1,3-木三糖。本研究揭示了参与1,3-木聚糖降解与利用的海洋细菌多样性，有助于理解海洋中细菌驱动的1,3-木聚糖循环过程，并为新型1,3-木聚糖酶的发掘提供了参考。