ABSCICS: Applied Bacterial Spore Control in Industrial and Clinical Settings

细菌内生孢子是地球上最具抵抗力的生命形式之一，允许细菌暴露于极端温度，干燥，消毒剂，辐射以及厌氧微生物的氧气中存活。生存的寿命是惊人的，可以衡量不是几十年或几百年，但在数百万。这些显著的结构是梭菌属细菌最重要的特征，并支持其致病成员的传播。然而，绝大多数梭菌是完全良性的，可以可持续地用于生产社会所需的化学品和燃料。梭菌也是有价值的治疗剂的来源（例如，BoTox和Xiaflex）。然而，它们潜在的最重要的用途之一在于它们通过利用其内生孢子作为实体瘤和微生物组的治疗递送载体的潜力。内生孢子是一种理想的药物。易于制备和纯化，一旦制成，它们非常适合长期储存。它们易于施用（静脉注射或口服），并且一旦递送，就依赖于自然过程（发芽）被激活-转化为营养细胞。然而，使它们成为理想递送载体的性质也损害了它们的感知安全性，因为氧敏感性营养细胞原位转化为内生孢子（孢子形成）导致高度抗性剂，其可以分散到外部环境中并在外部环境中存活。为了应对这种风险，SBRC已经创建了一种梭菌菌株，该菌株仅在规定的条件下产生孢子-一种条件孢子形成（Spoc）菌株。这允许在实验室条件下产生高孢子滴度，但是一旦在目标小生境（肿瘤或微生物组）中萌发，梭菌保持为营养细胞并且不能再次形成孢子。这种复杂的失能形式将确保避免梭菌的传播，从而满足监管机构的关注。除了它们在治疗递送中的用途之外，Spoc菌株对于基于孢子形成细菌的商业过程具有价值。这是因为在工业中不愿意使用产生孢子的细菌，因为它们很难从生产设施中去除。虽然无效突变体阻止孢子产生，但在氧敏感性厌氧菌的情况下，它使储存和维持种子菌株成为问题，因为营养细胞通过暴露于空气而迅速死亡。Spoc菌株允许通过在诱导剂存在下的生长将菌株储存和维持在孢子状态。随后在没有诱导剂的情况下进行大规模培养将防止生产设施的孢子污染。我们的概念是设计、构建和测试特定于确定的商业应用的梭菌的条件孢子形成（Spoc）菌株。控制细菌孢子形成的能力具有许多这样的用途，特别是与厌氧菌有关。这些涉及用于小生境特异性疾病和病症的治疗递送载体，作为防止处理设施的孢子污染和限制细菌向环境传播的手段，以及在一些应用中，控制孢子形成的诱导。

The bacterial endospore is one of the most highly resistant life-forms on earth and allows the bacterium to survive exposure to extremes of temperature, desiccation, disinfectants, radiation, and, in the case of anaerobes, oxygen. The longevity of survival is astounding and can be measured not in tens or hundreds of years but, in millions. These remarkable structures are the single most important feature of the bacterial genus Clostridium and underpin the spread of its disease-causing members. The vast majority of Clostridia are, however, entirely benign, and may be used sustainably to produce the chemicals and fuels society needs. Clostridia are also a source of valuable therapeutics (e.g., BoTox and Xiaflex). One of their potentially most significant uses, however, resides in their potential as therapeutic delivery vehicles for solid tumours and the microbiome through exploitation of their endospores. Endospores are an ideal pharmaceutical. Easy to prepare and purify, once made they are admirably suited to long term storage. They are simple to administer (intravenously or orally) and once delivered rely on a natural process (germination) to be activated - conversion to vegetative cells. However, the properties that make them ideal delivery vehicles also compromise their perceived safety, as the in situ conversion of an oxygen sensitive vegetative cell to an endospore (sporulation) leads to a highly resistant agent that can be dispersed to, and survive in, the external environment. To counter this risk, the SBRC has created a clostridial strain which only produces spores under defined conditions - a conditionally sporulating (Spoc) strain. This allows the generation of high spore titres under laboratory conditions, but once germinated in the target niche (tumour or microbiome) the Clostridia remain as vegetative cells and are unable to sporulate again. Such a sophisticated form of disablement will ensure that dissemination of Clostridia is avoided, thereby satisfying the concerns of regulatory agencies. Over and above their use in therapeutic delivery, Spoc strains are of value to commercial processes based on spore forming bacteria. This is because there is reluctance within industry to use bacteria that make spores as they are very difficult to remove from production facilities. While null mutants prevent spore production, in the case of an oxygen-sensitive anaerobe, it makes it problematic to store and maintain seed strains as vegetative cells are rapidly killed by exposure to air. A Spoc strain allows the storage and maintenance of strains in the spore state through growth in the presence of the inducers. Subsequent large-scale cultivation in the absence of inducers will prevent spore contamination of manufacturing facilities. Our concept is to design, build and test conditionally sporulating (Spoc) strains of Clostridia specific to identified commercial applications. The ability to control bacterial sporulation has a multitude of such uses, particularly in relation to anaerobes. These relate to therapeutic delivery vehicles for niche-specific diseases and disorders, as a means of both preventing spore contamination of process facilities and limiting the dissemination of the bacterium to the environment and, in some applications, the controlled induction of sporulation.