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Enhancing the biological reductive dechlorination of trichloroethylene with PHA from mixed microbial cultures (MMC)
Journal of Environmental Chemical Engineering ( IF 7.7 ) Pub Date : 2021-12-22 , DOI: 10.1016/j.jece.2021.107047
Neda Amanat 1 , Bruna Matturro 2 , Marianna Villano 1 , Laura Lorini 1 , Marta Maria Rossi 1 , Marco Zeppilli 1 , Simona Rossetti 2 , Marco Petrangeli Papini 1
Affiliation  

The biological reductive dechlorination (BRD) process is often limited by the lack of suitable electron donors, requiring the supply of long-lasting substrates to enhance the biological metabolism. Among the others, polyhydroxyalkanoates (PHA) are a particularly interesting slow-release source of electron-donors, being entirely biodegradable polyesters. Generally, industrial PHA production processes are based on pure culture fermentation with high related costs. In recent years, innovative and cost-effective PHA production from mixed microbial cultures (MMC) and waste feedstocks is attracting considerable attention. This research, for the first time, investigated the effect of distinctive types of PHA on the BRD process of trichloroethylene (TCE), in a continuous-flow lab-scale system using two PHA materials with different purity grade produced from MMC at pilot scale in comparison with a commercial PHA produced from pure culture. Promising results have been obtained with non-extracted MMC-PHA, a material consisting of both PHA (56%, w/w) and microbial cells, with constant production of acids over 110 days, which stimulated a nearly complete TCE dechlorination with the non-toxic ethene as the main byproduct (approximately 92%). Dehalococcoides mccartyi was the main microorganism responsible for TCE dechlorination process, representing ≥ 54.05% of the bacterial population, mainly carrying the reductive dehalogenase genes tceA and vcrA (≥9.17E+08 and ≥2.01E+07 gene copies/g of PHA or sand, respectively). This finding suggests the possibility to directly use PHA-rich biomass deriving from MMC production process, which does not require any polluting and expensive extraction procedures, as a novel material in the field of groundwater remediation with noticeable economic and environmental advantages.



中文翻译:

使用混合微生物培养物 (MMC) 中的 PHA 增强三氯乙烯的生物还原脱氯

生物还原脱氯 (BRD) 过程通常受到缺乏合适的电子供体的限制,需要提供长效底物来增强生物代谢。其中,聚羟基链烷酸酯 (PHA) 是一种特别有趣的电子供体缓释来源,它是完全可生物降解的聚酯。通常,工业PHA生产工艺基于纯培养发酵,相关成本高。近年来,利用混合微生物培养物 (MMC) 和废物原料生产具有成本效益的创新 PHA 引起了相当大的关注。本研究首次调查了不同类型的 PHA 对三氯乙烯 (TCE) 的 BRD 工艺的影响,在连续流动的实验室规模系统中,使用两种不同纯度等级的 PHA 材料从 MMC 中试规模生产,与从纯培养生产的商业 PHA 进行比较。使用非提取 MMC-PHA 获得了有希望的结果,这是一种由 PHA(56%,w/w ) 和微生物细胞,在 110 天内持续产生酸,这刺激了几乎完全的 TCE 脱氯,其中无毒乙烯作为主要副产物(约 92%)。Dehalococcoides mccartyi是TCE脱氯过程的主要微生物,占细菌种群的≥54.05%,主要携带还原性脱卤酶基因tceAvcrA(分别≥9.17E+08 和≥2.01E+07 基因拷贝/g PHA 或沙子)。这一发现表明,可以直接使用源自 MMC 生产过程的富含 PHA 的生物质,不需要任何污染和昂贵的提取程序,作为地下水修复领域的新型材料,具有显着的经济和环境优势。

更新日期:2022-01-21
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