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Author: search.filters.author.Kingkaew, EngkaratSubject: search.filters.subject.Genome analysis

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    Integrative genome analysis of bacteriocin-producing Lactiplantibacillus pentosus LNP1-39 and its synbiotic role in suppressing food-borne pathogens
    (2026-06-01)
    Jirakanjanasit, Thanadol
    ;
    Choovet, Natladda
    ;
    Booncharoen, Auttaporn
    ;
    Kingkaew, Engkarat
    ;
    Poothong, Saranporn
    Lactic acid bacteria were isolated from traditional Thai-fermented foods. Among these, the strain LNP1-39, closely related to Lactiplantibacillus pentosus, was selected for further study because of its non-pathogenic profile. The bacteriocins produced by L. pentosus LNP1-39 were proteinaceous substances that exhibited strong antimicrobial activity across a wide pH range (pH 2–11; 6400–2400 AU/mL) and thermal stability at 100 °C for 40 min (400 AU/mL). These bacteriocins showed a narrow antimicrobial spectrum, effectively targeting Gram-positive pathogens, such as Kocuria rhizophila MIII, Enterococcus faecalis JCM 5803<sup> T</sup>, and Listeria monocytogenes ATCC 19115. Comprehensive safety assessments, including whole-genome analysis and in vitro tests, confirmed a low risk of antibiotic resistance and the absence of virulence factors. Strain LNP1-39 was confirmed to be closely related to L. pentosus DSM 20314<sup> T</sup> via digital DNA‒DNA hybridization (dDDH; 75.4%), with average nucleotide identity (ANI) at 96.56% ANIb and 97.22% ANIm values. Additionally, LNP1-39 produces pediocin with notable similarity (76.29% identity to pediocin) and presents low risks for antibiotic-resistance genes or transfer genes while providing antioxidant properties. Strain LNP1-39 survived harsh gastrointestinal tract conditions and exhibited a favorable prebiotic index and positive prebiotic activity score when paired with polydextrose or isomalto-oligosaccharide. These findings support L. pentosus LNP1-39 as potential bacteriocin-producing lactic acid bacteria for further application in food preservation and pathogen control or as a synbiotic.
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    Optimization of astaxanthin production by Rhodotorula toruloides CB6-10/1 using response surface methodology and its genome analysis
    (2026-02-01)
    Butsararattanagomen, Pornthipa
    ;
    Tanasupawat, Somboon
    ;
    Kingkaew, Engkarat
    ;
    Kotatha, Ditpon
    ;
    Soontorngun, Nitnipa
    Astaxanthin is a valuable carotenoid with potent antioxidant properties and has broad applications in the pharmaceutical, nutraceutical, and cosmetic industries. In this study, Rhodotorula toruloides CB6-10/1, isolated from Canna indica L. flowers, was evaluated for astaxanthin production. The orange-red pigment was confirmed as astaxanthin via thin-layer chromatography and high-performance liquid chromatography, with quantification performed by spectrophotometry. Comprehensive genome analysis and production optimization of R. toruloides CB6-10/1 confirmed the presence of key astaxanthin biosynthesis genes, such as CrtYB, CrtI, CrtW, CrtZ, and CrtR, which facilitate the conversion of β-carotene to astaxanthin through hydroxylation and ketolation. The key parameters, including carbon and nitrogen sources, their concentrations, trace elements, agitation speed, and pH, were systematically evaluated to optimize production. Although copper appeared beneficial in the Plackett–Burman screening, its effect and those of other metals were not significant. Optimization using Response Surface Methodology for cost-effective nitrogen sources determined that a combination of 1.10 g/L yeast extract, 10.0 g/L peptone, and 0.50 g/L ammonium sulfate yielded the maximum astaxanthin production of 4.728 mg/L, under cultivation conditions of pH 4.5, 200 rpm, and 30 g/L glucose, representing a fourfold increase compared with the basal medium. This optimization not only enhances pigment production efficiency but also reduces dependency on costly trace elements, improving process scalability and economic feasibility. Overall, these results demonstrate R. toruloides CB6-10/1 as a promising microbial source for sustainable astaxanthin production with potential further applications.