Center for the Utilization of Biological Engineering in Space (CUBES), Berkeley, California, USA.
Department of Civil and Environmental Engineering, Stanford University, Stanford, California, USA.
Appl Environ Microbiol. 2024 Aug 21;90(8):e0060324. doi: 10.1128/aem.00603-24. Epub 2024 Jul 26.
Biodegradable plastics are urgently needed to replace petroleum-derived polymeric materials and prevent their accumulation in the environment. To this end, we isolated and characterized a halophilic and alkaliphilic bacterium from the Great Salt Lake in Utah. The isolate was identified as a species and designated "CUBES01." Full-genome sequencing and genomic reconstruction revealed the unique genetic traits and metabolic capabilities of the strain, including the common polyhydroxyalkanoate (PHA) biosynthesis pathway. Fluorescence staining identified intracellular polyester granules that accumulated predominantly during the strain's exponential growth, a feature rarely found among natural PHA producers. CUBES01 was found to metabolize a range of renewable carbon feedstocks, including glucosamine and acetyl-glucosamine, as well as sucrose, glucose, fructose, and further glycerol, propionate, and acetate. Depending on the substrate, the strain accumulated up to ~60% of its biomass (dry wt/wt) in poly(3-hydroxybutyrate), while reaching a doubling time of 1.7 h at 30°C and an optimum osmolarity of 1 M sodium chloride and a pH of 8.8. The physiological preferences of the strain may not only enable long-term aseptic cultivation but also facilitate the release of intracellular products through osmolysis. The development of a minimal medium also allowed the estimation of maximum polyhydroxybutyrate production rates, which were projected to exceed 5 g/h. Finally, also, the genetic tractability of the strain was assessed in conjugation experiments: two orthogonal plasmid vectors were stable in the heterologous host, thereby opening the possibility of genetic engineering through the introduction of foreign genes.
The urgent need for renewable replacements for synthetic materials may be addressed through microbial biotechnology. To simplify the large-scale implementation of such bio-processes, robust cell factories that can utilize sustainable and widely available feedstocks are pivotal. To this end, non-axenic growth-associated production could reduce operational costs and enhance biomass productivity, thereby improving commercial competitiveness. Another major cost factor is downstream processing, especially in the case of intracellular products, such as bio-polyesters. Simplified cell-lysis strategies could also further improve economic viability.
为了替代石油衍生的聚合材料并防止其在环境中积累，我们迫切需要可生物降解的塑料。为此，我们从犹他州的大盐湖中分离并鉴定了一种嗜盐和嗜碱细菌。该分离物被鉴定为一种 种，并被命名为“CUBES01”。全基因组测序和基因组重建揭示了该菌株独特的遗传特征和代谢能力，包括常见的聚羟基烷酸酯（PHA）生物合成途径。荧光染色鉴定了细胞内聚酯颗粒，这些颗粒主要在菌株的指数生长期积累，这是在天然 PHA 生产者中很少发现的特征。CUBES01 被发现可以代谢多种可再生碳源，包括葡糖胺和乙酰葡糖胺，以及蔗糖、葡萄糖、果糖，以及进一步的甘油、丙酸盐和醋酸盐。根据底物的不同，该菌株可将高达约 60%的生物量（干重/湿重）积累在聚（3-羟基丁酸酯）中，同时在 30°C 下达到 1.7 小时的倍增时间，最佳渗透压为 1M 氯化钠和 pH 值为 8.8。该菌株的生理偏好不仅可以实现长期无菌培养，还可以通过渗透压裂解促进细胞内产物的释放。最小培养基的开发还允许估计最大的聚羟基丁酸酯生产速率，预计超过 5g/h。最后，还评估了该菌株的遗传可操作性，在共轭实验中：两个正交质粒载体在异源宿主中稳定，从而为通过引入外源基因进行遗传工程开辟了可能性。
通过微生物生物技术可以解决对合成材料的可再生替代品的迫切需求。为了简化此类生物过程的大规模实施，使用可持续和广泛可用的原料的稳健细胞工厂是至关重要的。为此，非无菌生长相关的生产可以降低运营成本并提高生物量生产力，从而提高商业竞争力。另一个主要的成本因素是下游加工，特别是对于细胞内产物，如生物聚酯。简化的细胞裂解策略也可以进一步提高经济可行性。
