Over the last decades, the use of mixed microbial communities has attracted increasing scientific attention due to their potential biotechnological applications in several emerging technological platforms such as the carboxylate, bioplastic, syngas and bio-electrochemical synthesis platforms. However, this increasing interest has not been accompanied by a parallel development of suitable cryopreservation techniques for microbial communities. While cryopreservation methods for the long-term storage of axenic cultures are well established, their effectiveness in preserving the microbial diversity and functionality of microbial communities has rarely been studied. In this study, the effect of the addition of different cryopreservation agents on the long-term storage of microbial communities at -80 °C was studied using a stable enrichment culture converting syngas into acetate and ethanol. The cryopreservation agents considered in the study were glycerol, dimethylsulfoxide, polyvinylpyrrolidone, Tween 80 and yeast extract, as well as with no addition of cryopreservation agent. Their effectiveness was evaluated based on the microbial activity recovery and the maintenance of the microbial diversity and community structure upon revival of the microbial community. The results showed that the commonly used glycerol and no addition of cryopreservation agent were the least recommendable methods for the long-term frozen storage of microbial communities, while Tween 80 and polyvinylpyrrolidone were overall the most effective. Among the cryoprotectants studied, polyvinylpyrrolidone and especially Tween 80 were the only ones assuring reproducible results in terms of microbial activity recovery and microbial community structure preservation.

中文翻译：

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冷冻保存和快速恢复富含合成气的微生物群落。

在过去的几十年中，由于混合微生物群落在多种新兴技术平台（例如羧酸盐，生物塑料，合成气和生物电化学合成平台）中的潜在生物技术应用，它们的使用已引起越来越多的科学关注。然而，这种日益增长的兴趣并未伴随着针对微生物群落的合适的冷冻保存技术的并行发展。虽然冷冻保存方法可以长期保存菌种培养物，但很少研究其在保存微生物多样性和微生物群落功能方面的有效性。在这个研究中，使用稳定的富集培养将合成气转化为乙酸盐和乙醇，研究了在-80°C下添加不同的低温保存剂对微生物群落长期保存的影响。研究中考虑的冷冻保存剂为甘油，二甲基亚砜，聚乙烯吡咯烷酮，吐温80和酵母提取物，以及不添加冷冻保存剂。基于微生物活性的恢复以及微生物群落恢复后微生物多样性和群落结构的维持，评估了它们的有效性。结果表明，对于长期冷冻保存微生物群落，最不推荐的方法是使用常用的甘油，而无需添加冷冻保存剂，而吐温80和聚乙烯吡咯烷酮总体上是最有效的。