Novel strain development for the mycoprotein fungus Fusarium venenatum

菌蛋白真菌 Fusarium v​​enenatum 新菌株的开发

• 批准号: 2593581
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2593581
• 关键词: Novel; strain; development; mycoprotein; fungus

There is ever growing demand for meat replacement protein sources on environmental and health grounds. The fungus Fusarium venenatum is used in the production of mycoprotein, a high-protein, low cholesterol meat substitute sold under the trade name 'Quorn', which has been very commercially successful. A particular strain A3/5 was identified in the 1960s, being chosen for mycoprotein production as it yields a high protein textured product with negligible toxins under industrial growth conditions. However, there are inefficiencies and problems. For example after prolonged growth the fungus is prone to excess branching unsuitable for Quorn production, has low levels of certain vitamins, and there remains a risk of mycotoxin production. Perhaps surprisingly the same strain A3/5 has been used since the 1970s with no strain development. Therefore there is now commercial and environmental interest in obtaining novel strains with improved characteristics for mycoprotein production. In parallel, scientific advances have recently been made in fungal genomics and genetic manipulation meaning that F. venenatum is an attractive model organism for biotechnological exploitation, with research having the potential for significant fundamental scientific and real world applied impact. Experimental Approaches, Methodology and Techniques We plan to use leading genomic, molecular biology, biochemical and classical culturing techniques to explore strain improvement in F. venenatum. A genome sequence of A3/5 is already available to facilitate investigations. (1) Sexual biology of F. venenatum. The species is only known to reproduce asexually, which has impeded strain improvement. However, we have recently developed a molecular sex-test diagnostic, which has identified F. venenatum isolates of different MAT1-1 and MAT1-2 mating type needed for sexual reproduction. We plan to screen isolates by qRT-PCR for expression of genes required for sexual development and then mate chosen isolates under conditions favourable for sexual reproduction, using a range of microscopy to monitor development. If sex can be induced, there is the exciting prospect that strains with desirable characteristics (e.g. higher growth rate and vitamin content, absence of mycotoxins) can be crossed and offspring identified with combinations of favourable traits; the sexual cycle may also generate completely novel, favourable genotypes. This approach is attractive as sexual breeding is a natural, rather than GM, method of strain development allowing exploitation of strains. The discovery of a sexual cycle in F. venenatum would be a world first and provide general insights into fungal sexuality and asexuality. (2) Manipulation of F. venenatum - classical genetics. Pilot studies suggest that diploid strains are more stable under prolonged fermenter growth than the haploid strain A3/5 in current use. We will generate diploid strains to see if more stable production strains with less branching can be obtained, drawing on cutting-edge microscopy and proteomic methods developed at Marlow Foods to monitor hyphal branching and protein composition. We will also develop parasexual crossing to generate novel combinations of traits in haploid strains. (3) Manipulation of F. venenatum - genome editing. GM and CRISPR genome-editing tools will be used to try and alter traits of interest e.g. mycotoxin synthesis and vitamin production. Electronic nose GC-MS will be used to identify undesirable flavour volatiles that also might be removed. Although arising strains could not yet be used commercially, they will provide key insights which might be exploited by (1+2) above.

基于环境和健康原因，对肉类替代蛋白质来源的需求不断增长。真菌Fusarium venenatum用于生产真菌蛋白，一种高蛋白、低胆固醇的肉类替代品，以商品名“Quorn”出售，在商业上非常成功。在20世纪60年代鉴定了一种特殊的菌株A3/5，选择用于真菌蛋白生产，因为它在工业生长条件下产生高蛋白质构产品，毒素可忽略不计。然而，存在效率低下和问题。例如，在长时间生长后，真菌容易产生不适合Quorn生产的过度分支，某些维生素水平低，并且仍然存在产生真菌毒素的风险。也许令人惊讶的是，自20世纪70年代以来一直使用相同的菌株A3/5，而没有菌株发展。因此，现在在商业和环境方面对获得具有改进的真菌蛋白生产特性的新菌株有兴趣。与此同时，最近在真菌基因组学和遗传操作方面取得了科学进展，这意味着F。venenatum是生物技术开发的一种有吸引力的模式生物，其研究具有重大基础科学和真实的世界应用影响的潜力。 实验方法，方法和技术我们计划使用领先的基因组学，分子生物学，生物化学和经典培养技术来探索F。毒液A3/5的基因组序列已经可以用于促进研究。(1)性生物学的研究。毒液该物种只知道无性繁殖，这阻碍了菌株的改进。然而，我们最近开发了一种分子性别测试诊断，它已经确定了F。不同交配型的MAT 1 -1和MAT 1 -2菌株有性繁殖所需的交配时间不同。我们计划通过qRT-PCR筛选性发育所需基因表达的分离株，然后在有利于有性生殖的条件下选择交配分离株，使用一系列显微镜监测发育。如果可以诱导有性生殖，那么就有一个令人兴奋的前景，即可以杂交具有理想特性（例如，更高的生长速度和维生素含量，不含真菌毒素）的菌株，并鉴定出具有有利特性组合的后代;有性周期也可能产生全新的有利基因型。这种方法是有吸引力的，因为有性繁殖是一种自然的，而不是转基因的菌株开发方法，允许利用菌株。在F. venenatum将是世界上第一个，并提供了真菌性和无性的一般见解。(2)操纵F。venenatum -古典遗传学。初步研究表明，二倍体菌株在长期发酵罐生长下比目前使用的单倍体菌株A3/5更稳定。我们将产生二倍体菌株，看看是否可以获得更稳定的生产菌株与较少的分支，利用尖端的显微镜和蛋白质组学方法开发的马洛食品监测菌丝分支和蛋白质组成。我们还将开发准有性杂交，以在单倍体品系中产生新型性状组合。(3)操纵F。venenatum -基因组编辑。GM和CRISPR基因组编辑工具将用于尝试和改变感兴趣的性状，例如霉菌毒素合成和维生素生产。电子鼻GC-MS将用于识别也可能被去除的不良风味挥发物。虽然新出现的菌株还不能用于商业用途，但它们将提供可能被上述（1+2）利用的关键见解。