Samuel M. M. Prudence

Antimicrobial peptides (AMPs) are promising candidates for next-generation therapeutics due to their broad-spectrum activity and reduced propensity for resistance, making them valuable in medicine, agriculture, and biotechnology. However, traditional AMP production methods including isolation from natural sources and chemical synthesis are costly, inefficient, and environmentally unsustainable, particularly for longer or post-translationally modified peptides. While heterologous expression has emerged as a scalable and versatile alternative, its success depends strongly on host selection and tailored optimisation strategies. This review examines recent advances in fungal systems as platforms for AMP production. Fungal systems, and particularly yeasts such as Pichia pastoris, offer rapid growth, low-cost fermentation, secretion capacity, and the ability to perform key post-translational modifications (PTMs), making them leading hosts for recombinant AMPs. We outline strain choice and engineering strategies that enhance AMP yield and bioactivity, including promoter and codon optimisation, secretion signal choice, fusion partners, and the construction of tandem or chimeric AMPs. By integrating current methodologies and case studies, this review aims to guide future efforts toward efficient, scalable, and commercially viable AMP manufacturing in fungal hosts, positioning fungal biotechnology as a key enabler in the development of next-generation antimicrobial solutions.

Background: Conventional methods of agricultural pest control and crop fertilisation are unsustainable. To meet growing demand, we must find ecologically responsible means to control disease and promote crop yields. The root-associated microbiome can aid plants with disease suppression, abiotic stress relief, and nutrient bioavailability. The aim of the present work was to profile the community of bacteria, fungi, and archaea associated with the wheat rhizosphere and root endosphere in different conditions. We also aimed to use ¹³CO₂ stable isotope probing (SIP) to identify microbes within the root compartments that were capable of utilising host-derived carbon. Results: Metabarcoding revealed that community composition shifted significantly for bacteria, fungi, and archaea across compartments. This shift was most pronounced for bacteria and fungi, while we observed weaker selection on the ammonia oxidising archaea-dominated archaeal community. Across multiple soil types we found that soil inoculum was a significant driver of endosphere community composition, however, several bacterial families were identified as core enriched taxa in all soil conditions. The most abundant of these were Streptomycetaceae and Burkholderiaceae. Moreover, as the plants senesce, both families were reduced in abundance, indicating that input from the living plant was required to maintain their abundance in the endosphere. Stable isotope probing showed that bacterial taxa within the Burkholderiaceae family, among other core enriched taxa such as Pseudomonadaceae, were able to use root exudates, but Streptomycetaceae were not. Conclusions: The consistent enrichment of Streptomycetaceae and Burkholderiaceae within the endosphere, and their reduced abundance after developmental senescence, indicated a significant role for these families within the wheat root microbiome. While Streptomycetaceae did not utilise root exudates in the rhizosphere, we provide evidence that Pseudomonadaceae and Burkholderiaceae family taxa are recruited to the wheat root community via root exudates. This deeper understanding crop microbiome formation will enable researchers to characterise these interactions further, and possibly contribute to ecologically responsible methods for yield improvement and biocontrol in the future.