The key to the resource recycling of saline wastes in form of polyhydroxyalkanoates (PHA) is to enrich mixed cultures with salt tolerance and PHA synthesis ability. However, the comparison of saline sludge from different sources and the salt tolerance mechanisms of salt-tolerant PHA producers need to be clarified. In this study, three kinds of activated sludge from different salinity environments were selected as the inoculum to enrich salt-tolerant PHA producers under aerobic dynamic feeding (ADF) mode with butyric acid dominated mixed volatile fatty acid as the substrate. The maximum PHA content (PHAm) reached 0.62 ± 0.01, 0.62 ± 0.02, and 0.55 ± 0.03 g PHA/g VSS at salinity of 0.5%, 0.8%, and 1.8%, respectively. Microbial community analysis indicated that , , and were dominant salt-tolerant PHA producers at low salinity, , , and were dominant salt-tolerant PHA producers at high salinity. High salinity and ADF mode had synergistic effects on selection and enrichment of salt-tolerant PHA producers. Combined correlation network with redundancy analysis indicated that trehalose synthesis genes and betaine related genes had positive correlation with PHAm, while extracellular polymeric substances (EPS) content had negative correlation with PHAm. The compatible solutes accumulation and EPS secretion were the main salt tolerance mechanisms of the PHA producers. Therefore, adding compatible solutes is an effective strategy to improve PHA synthesis in saline environment.

中文翻译：

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不同盐环境下生产混合培养物的聚羟基脂肪酸酯（PHA）的富集性能和耐盐性


以聚羟基脂肪酸酯（PHA）形式回收含盐废物的关键是丰富具有耐盐性和PHA合成能力的混合培养物。然而，不同来源的盐渍污泥的比较以及耐盐PHA生产商的耐盐机制需要澄清。本研究选择来自不同盐度环境的三种活性污泥作为接种物，以丁酸为主的混合挥发性脂肪酸为底物，在好氧动态投料（ADF）模式下富集耐盐PHA生产剂。在盐度为0.5%、0.8%和1.8%时，最大PHA含量(PHAm)分别达到0.62±0.01、0.62±0.02和0.55±0.03g PHA/g VSS。微生物群落分析表明， 、 、 和 是低盐度下耐盐PHA 的优势生产者， 、 、 和 是高盐度下耐盐PHA 的优势生产者。高盐度和ADF模式对耐盐PHA生产者的选择和富集具有协同作用。联合相关网络与冗余分析表明，海藻糖合成基因和甜菜碱相关基因与PHAm呈正相关，而胞外聚合物（EPS）含量与PHAm呈负相关。相容性溶质积累和EPS分泌是PHA生产者的主要耐盐机制。因此，添加相容性溶质是提高盐水环境中PHA合成的有效策略。