Antimicrobial peptides (AMPs) are natural peptides possessing antimicrobial activities. These peptides are important components of the innate immune system. They are found in various organisms. AMP screening and identification by experimental techniques are laborious and time-consuming tasks. Alternatively, computational methods based on machine learning have been developed to screen potential AMP candidates prior to experimental verification. Although various AMP prediction programs are available, there is still a need for improvement to reduce false positives (FPs) and to increase the predictive accuracy. In this work, several well-known single and ensemble machine learning approaches have been explored and evaluated based on balanced training datasets and two large testing datasets. We have demonstrated that the developed program with various predictive models has high performance in differentiating between AMPs and non-AMPs. Thus, we describe the development of a program for the prediction and recognition of AMPs using MaxProbVote, which is an ensemble model. Moreover, to increase prediction efficiency, the ensemble model was integrated with a new hybrid feature based on logistic regression. The ensemble model integrated with the hybrid feature can effectively increase the prediction sensitivity of the developed program called Ensemble-AMPPred, resulting in overall improvements in terms of both sensitivity and specificity compared to those of currently available programs.

Ammonium is a source of fermentable inorganic nitrogen essential for the growth and development of filamentous fungi. It is involved in several cellular metabolic pathways underlying nitrogen transport and assimilation. Ammonium can be transferred into the cell by an ammonium transporter. This study explored the role of ammonium transporters in nitrogen metabolism and cell biomass production in Aspergillus oryzae strain BCC 7051. Specific sequences encoding ammonium transporters (Amts) in A. oryzae were identified using genomic analysis. Four of the identified ammonium transporter genes, aoamt1-aoamt4, showed similarity in deduced amino acid sequences to the proteins in the ammonium transporter/methylammonium permease (AMT/MEP) family. Transcriptional analysis showed that the expression of aoamt2 and aoamt3 was ammonium-dependent, and was highly upregulated under ammonium-limited conditions. Their functional roles are characterized by genetic perturbations. The gene disruption and overexpression of aoamt3 indicated that the protein encoded by it was a crucial ammonium transporter associated with nitrogen metabolism and was required for filamentous growth. Compared with the wild type, the aoamt3-overexpressing strain showed superior growth performance, high biomass yield, and low glucose consumption. These results shed light on further improvements in the production of potent bioproducts by A. oryzae by manipulating the ammonium uptake capacity and nitrogen metabolism.

Microbial lipid production with cost effectiveness is a prerequisite for the oleochemical sector. In this work, genome-wide transcriptional responses on the utilization of xylose and glucose in oleaginous Aspergillus oryzae were studied with relation to growth and lipid phenotypic traits. Comparative analysis of the active growth (t1) and lipid-accumulating (t2) stages showed that the C5 cultures efficiently consumed carbon sources for biomass and lipid production comparable to the C6 cultures. By pairwise comparison, 599 and 917 differentially expressed genes (DEGs) were identified in the t1 and t2 groups, respectively, in which the consensus DEGs were categorized into polysaccharide-degrading enzymes, membrane transports, and cellular processes. A discrimination in transcriptional responses of DEGs set was also found in various metabolic genes, mostly in carbohydrate, amino acid, lipid, cofactors, and vitamin metabolisms. Although central carbohydrate metabolism was shared among the C5 and C6 cultures, the metabolic functions in acetyl-CoA and NADPH generation, and biosynthesis of terpenoid backbone, fatty acid, sterol, and amino acids were allocated for leveraging biomass and lipid production through at least transcriptional control. This study revealed robust metabolic networks in the oleaginicity of A. oryzae governing glucose/xylose flux toward lipid biosynthesis that provides meaningful hints for further process developments of microbial lipid production using cellulosic sugar feedstocks.

Lactiplantibacillus species have been historically used for food applications. Although several species are regarded as safe according to their regulatory status, the safety issues and functional roles of these lactic acid bacteria have been given attention. A selected Lactiplantibacillus strain TBRC 20328, with probiotic properties isolated from fermented Isan-style pork sausage (Mam), was evaluated for its safety through whole-genome sequencing and analysis using integrative bioinformatics tools. The metabolic genes were assessed through comparative genome analysis among Lactiplantibacillus species. The genome of the strain TBRC 20328 consisted of one circular chromosome (3.49 Mb) and five plasmids (totaling 0.25 Mb), encoding 3056 and 284 protein-coding genes, respectively. It exhibited an average nucleotide identity (ANI) with other Lactiplantibacillus pentosus strains of over 95%. Whole-genome analysis confirmed the absence of virulence and antimicrobial resistance genes, supporting its safety for food applications. Functional annotation revealed clusters for bacteriocins (plantaricin EF and pediocin) and polyketides, indicating potential roles in biopreservation and host interactions. Genes involved in the biosynthesis of some short-chain fatty acids and exopolysaccharides were also identified. Comparative genomic analysis across 33 other Lactiplantibacillus strains identified 2380 orthogroups, with 94 unique to the Lp. pentosus group. These included gene clusters involved in malonate decarboxylation, leucine biosynthesis, and 5-oxoprolinase activity. Such distinct genomic features emphasize the sustainable biotechnological potential and safety of Lp. pentosus TBRC 23028. Together, the findings highlight its promise as a safe and functional probiotic candidate with broad applications in functional food development and precision fermentation technologies.