Kingkaew, Engkarat

Preferred name

Kingkaew, Engkarat

Main Affiliation

School of Science

engkarat.ki@kmitl.ac.th

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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
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Tanasupawat, Somboon
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Kingkaew, Engkarat
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Kotatha, Ditpon
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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.
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Genomic Assessment, Metabolic Profile Mapping, and Anti-Helicobacter pylori Activity of Lactococcus lactis SK2-659 from Thai Fermented Green Mustard (Pak-kad-dong)
(2026-01-01)
Kingkaew, Engkarat
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Woraprayote, Weerapong
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Sitdhipol, Jaruwan
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Vilaichone, Ratha Korn
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Visessanguan, Wonnop
Probiotics play crucial roles in promoting gut health, enhancing immunity, and combating pathogenic microorganisms, with increasing interest in their applications in the food and therapeutic industries. Lactococcus lactis, a well-known lactic acid bacterium, has emerged as a promising candidate owing to its probiotic traits and safety profile. In this study, we investigated the probiotic potential and genomic profile of Lactococcus lactis SK2-659, a strain isolated from Thai fermented green mustard (Pak-kad-dong). Genomic analysis revealed numerous genes associated with probiotic traits, including stress tolerance, adhesion, and antimicrobial activity, with a particular focus on bacteriocin SK2-659, which was effective against pathogenic bacteria such as Helicobacter pylori. The bacteriocin produced by L. lactis SK2-659, identified as nisin Z, disrupts bacterial membranes via pore formation, leading to cell lysis. Metabolomic profiling further highlighted its ability to increase carbohydrate and amino acid metabolism, supporting cell growth and survival in acidic environments. Also, amino acid metabolism (elevated tryptophan, tyrosine, histidine) supports acid tolerance and immune modulation. Tryptophan metabolism produces indole derivatives, which are known to benefit gut health and immunity. Additionally, strain SK2-659 demonstrated strong tolerance to gastrointestinal conditions, high adhesion capacity to intestinal cells, and immunomodulatory effects, contributing to gut health. Safety assessments confirmed the absence of virulence factors, pathogenic traits, and antibiotic resistance genes, along with a lack of biogenic amine production, underscoring its suitability for food and health applications. These findings establish L. lactis SK2-659 as a promising probiotic candidate with potential industrial applications in functional foods, food preservation, and therapeutic products. Given its probiotic properties, antimicrobial activity, and safety profile, this strain is particularly suited for the food industry as a functional food ingredient and natural bio-preservative, as well as the healthcare and pharmaceutical industries for use in therapeutic probiotics and gut health formulations.
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Lactic acid bacteria in the gastrointestinal tract: Anti-helicobacter pylori
(2024-06-03)
Techo, Sujitra
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Kingkaew, Engkarat
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Tanasupawat, Somboon
Numerous bacterial species have been found throughout the human GI tract, which consists of the oral cavity, stomach, intestine, and colon. Lactic acid bacteria (LAB), including Lactobacillus (L. ) acidophilus, L. salivarius, L. johnsonii, L. crispatus, L. casei, L. paracasei, L. rhamnosus, L. reuteri, L. oris, L. vaginalis, L. gasseri, L. plantarum, L. buchneri, L. mali, L. ruminis, L. delbrueckii, L. sakei, L. fermentum, L. helviticus, and L. brevis ; Streptococcus ( S. ) salivarius, S. pneumonia, S. mitis, S. oralis, S. parasanguinis, S. anginosus, S. constellatus, S. caprinus, and S. mutans ; Leuconostoc (Ln. ) mesenteroides and Ln. argentinum ; Lactococcus (Lc.) lactis; and Enterococcus (En. ) strains, are distributed throughout the human GI tract. The bacterial microbiota in humans changes when infected with Helicobacter (H. ) pylori. Moreover, antibiotics and proton pump inhibitors (PPIs) used in the regimen influence microbial microbiota. However, alteration of bacterial diversity is rather complicated and has conflicting effects. To maintain microbial balance in the GI tract, several studies have used probiotics as adjunctive therapy to reduce the number of H. pylori in infected humans, replacing antibiotics alone. Probiotics have shown a higher eradication rate of H. pylori when compared with antibiotics alone. Bacteriocin production by LAB is one of the interesting mechanisms that can inhibit the growth of H. pylori. Bacteriocins and bacteriocin-like substances exhibiting antibacterial properties against H. pylori have been reported. These active peptides could be exploited to develop novel therapeutics for treating H. pylori infection.
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Enhancement of astaxanthin production in novel red yeast Rhodosporidiobolus sp. SP3-3/4 and genomic characterization
(2025-10-01)
Phuengjayaem, Sukanya
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Kingkaew, Engkarat
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Hoondee, Patcharaporn
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Tanasupawat, Somboon
Astaxanthin is a red carotenoid and potent antioxidant with anti-inflammatory, anti-cancer, neuroprotective, and immuno-enhancing benefits. This study focused on enhancing astaxanthin production using a novel red yeast, strain SP3-3/4, through genomic analysis. Strain SP3-3/4 shared 99.66% sequence identity in the D1/D2 domain of the large subunit rRNA gene with Rhodosporidiobolus ruineniae CBS 5001<sup>T</sup>. Whole-genome analysis indicated 82.54% similarity to R. ruineniae JCM 8097<sup>T</sup>, with average nucleotide identity (ANI) values below 80% for other strains. The ANI result, lower than the 95% cutoff, confirms SP3-3/4 as a novel species, Rhodosporidiobolus sp. SP3-3/4. Key astaxanthin synthesis genes, including CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, and CrtZ, were annotated. Astaxanthin production was verified using HPLC and LC-MS. Optimization of medium composition and physical parameters identified optimal conditions as 20 g/L sucrose, 3 g/L yeast extract, and 5 g/L peptone, with an initial medium pH of 6.5. Maximum cell growth and astaxanthin content, reaching 9.615 g/L and 0.46 mg/g DCW, respectively, were achieved after 5 days of cultivation, corresponding to an astaxanthin yield of 6.93 mg/L and a productivity rate of 1.39 mg/L/day. Notably, a maximum productivity of 1.45 mg/L/day occurred in 3 days. These findings elucidated comprehensive optimization of astaxanthin production, incorporating functional genomic assessment and analysis of protein-encoded genes of astaxanthin-producing yeast Rhodosporidiobolus sp. SP3-3/4. Such insights represent valuable biological resources with significant implications for diverse biotechnological and bioinformatics applications.
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ENHANCING SUGAR RECOVERY FROM SUGARCANE BAGASSE: OPTIMIZING MICROWAVE-ASSISTED ALKALINE PRETREATMENT METHODS FOR BIOBASED ENERGY
(2025-01-01)
Kingkaew, Engkarat
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Tanasupawat, Somboon
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Phuengjayaem, Sukanya
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Poothong, Saranporn
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Ochaikul, Duangjai
This study optimized microwave-assisted alkaline pretreatment for enhancing sugar recovery from sugarcane bagasse. Bagasse was dried, ground, and sieved to a uniform particle size before undergoing pretreatment with sodium hydroxide (NaOH). The effects of microwave power, duration, and NaOH concentration were investigated. Optimal conditions were identified as 800 W microwave power, 8% (w/v) NaOH, and a 2-minute duration (18.69 ± 0.05 g/L). An NaOH concentration of 8% (w/v) achieved high sugar recovery while minimizing chemical use, highlighting the balance between efficiency and sustainability. These findings provide a foundation for improving lignocellulosic biomass pretreatment for biofuel and biochemical production.
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Yeasts: Genomics, biotechnology and health benefits
(2024-09-16)
Tanasupawat, Somboon
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Kingkaew, Engkarat
Yeast, with its roots in taxonomy and ecology, has become a crucial element in modern biotechnology. It offers profound insights into genetic diversity and ecological roles. This book explores yeast's lasting importance and its significant impact across various scientific disciplines and societal contexts. Yeast serves as a catalyst for scientific innovation and contributes to sustainable advancements in biotechnology and beyond. The importance of yeast is multifaceted. In taxonomy and ecology, yeast is vital for understanding industrial yeast taxonomy, distribution, and ecological adaptations. Genomic analysis of yeast provides critical insights, with practical applications such as astaxanthin production. In biotechnology, yeast is essential for producing alcoholic beverages. It is involved in traditional fermentation processes and the sensory complexities of these beverages. Yeast also offers potential health benefits associated with moderate alcohol consumption and has a significant influence on Asian alcoholic beverages. Additionally, yeast plays a crucial role in the production of amino acids, lipid synthesis for biofuels and cosmetics, and the use of yeast beta-glucan in cosmeceuticals. Yeast significantly contributes to health-focused foods by providing nutritional benefits in bread and baking and acting as probiotics in fermented foods. Its role is especially notable in Japanese fermented foods. In agriculture, yeast is used in animal feed additives and demonstrates biocontrol potential. Its bioactive compounds effectively mitigate plant diseases and enhance crop yield, highlighting its importance in sustainable agricultural practices.
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Functional and genomic characterization of Pediococcus pentosaceus NR4-4 reveals a safe bacteriocinogenic probiotic with strong anti-listerial activity and prebiotic metabolism
(2026-05-01)
Ratthanachot, Natnarin
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Woraprayote, Weerapong
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Janyaphisan, Thitiphorn
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Tanasupawat, Somboon
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Ochaikul, Duangjai
The growing interest in bacteriocin-producing lactic acid bacteria from traditional fermented foods has highlighted the value of strains that combine antimicrobial activity, probiotic functionality, and genome-supported safety. This study presents an integrated functional and probiogenomic characterization of Pediococcus pentosaceus NR4-4 isolated from Thai fermented mustard greens. The strain was found to produce a heat-stable class IIa bacteriocin with pronounced inhibitory activity against Listeria monocytogenes . In addition, NR4-4 exhibited strong tolerance to simulated gastrointestinal conditions and demonstrated effective adhesion to Caco-2 intestinal epithelial cells. In vitro safety evaluations confirmed that the strain was non-hemolytic and did not exhibit cytotoxic effects toward AGS or Caco-2 cell lines. Whole-genome sequencing verified species identity and revealed the presence of pediocin-related gene clusters, carbohydrate-active enzymes associated with fructooligosaccharide utilization, and a favorable genome-based safety profile. Notably, no virulence factors, biogenic amine biosynthesis pathways, plasmids, or transferable antimicrobial resistance determinants were detected. The preferential metabolism of fructooligosaccharides further suggests compatibility with synbiotic formulations. Overall, these findings indicate that P. pentosaceus NR4-4 is a genomically supported, safe, and multifunctional probiotic candidate with potential applications in food biopreservation and functional food development.
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Genomic Characterization and Hydrolysis Enzyme of Piscibacillus salipiscarius RBU1-1ᵀ and Allobacillus salarius SKP4-8ᵀ Isolated from Fermented Fish Products
(2026-01-01)
Namwong, Sirilak
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Chaimongkol, Apichai
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Kingkaew, Engkarat
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Phongsopitanun, Wongsakorn
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Chamroensaksri, Nitcha
Two halophilic bacterial strains, Piscibacillus salipiscarius RBU1-1ᵀ and Allobacillus salarius SKP4-8ᵀ, were isolated from traditional Thai fermented foods, namely pla-ra from Ratchaburi, Thailand, and ka-pi from Samut Sakhon, Thailand, respectively. Comparative genomics confirmed their taxonomic distinctiveness, with RBU1-1ᵀ representing a novel species and SKP4-8ᵀ showing clear genomic separation from its closest relatives. The draft genomes were 2.99 Mb (36.7 mol% G+C) for RBU1-1ᵀ and 2.59 Mb (38.8 mol% G+C) for SKP4-8ᵀ. Both strains encoded hydrolytic enzymes and secondary metabolite pathways, with SKP4-8ᵀ displaying higher protease activity and RBU1-1ᵀ harboring ectoine biosynthetic and stress-response genes. RBU1-1ᵀ encoded the biosynthesis pathways for ectoine, tryptophan, and thiamine, while SKP4-8ᵀ encoded thiamine, riboflavin, coenzyme A, and menaquinone, indicating their potential contributions to postbiotic and nutritional value. Safety assessment revealed the absence of biogenic amine, antibiotic biosynthesis, and major virulence genes in both strains. Although antimicrobial resistance-associated genes were detected, no complete clusters were identified, suggesting low phenotypic risk. Computational pathogenicity prediction indicated a low probability for RBU1-1ᵀ (0.242) and a higher probability for SKP4-8ᵀ (0.945), though these require cautious interpretation. Overall, genomic evidence and enzymatic activity support RBU1-1ᵀ and SKP4-8ᵀ as safe, functional starter culture candidates, with RBU1-1ᵀ showing strong potential through postbiotic biosynthesis and SKP4-8ᵀ through proteolytic activity.
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Characterization of red pigmented yeasts and genes associated with astaxanthin synthesis in Rhodotorula mucilaginosa HL26-1 and Rhodotorula paludigena LL69-1
(2026-01-01)
Hoondee, Patcharaporn
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Tedsree, Nisachon
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Phuengjayaem, Sukanya
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Kingkaew, Engkarat
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Sritularak, Boonchoo
Background: Astaxanthin, a red xanthophyll carotenoid, is a powerful antioxidant, anticancer, and glucose and lipid homeostasis regulator. Some pigmented yeasts belonging to the genus Rhodotorula, the well-known yeast for beta-carotene production, have been reported as natural astaxanthin producers. However, the lack of genomic data on astaxanthin-producing strains within these species hinders the identification of biosynthetic routes, molecular characterization of these pathways, and gene editing applications. Methods: This study explored the diversity and astaxanthin production capability of cultivable pigmented yeast in flower samples. The astaxanthin production ability was inspected by three consecutive methods, including thin-layer chromatography (TLC) for the preliminary step, followed by quantitative spectrophotometry and high-performance liquid chromatography (HPLC) for qualitative validation. The draft genome sequence and astaxanthin-producing genes of astaxanthin-producing yeasts were examined. Results: Twelve of 23 yeasts from floral samples exhibited natural pigmentation, with colors ranging from pinkish-orange to red, and exhibited the potential for astaxanthin synthesis. These yeasts were Rhodotorula paludigena (three strains) and Rhodotorula mucilaginosa (nine strains). Among R. mucilaginosa strains, HL26-1 had the greatest astaxanthin content (104.98 ± 0.13 μg/g DCW) and yield (0.9280 ± 0.0012 mg/L). Strain LL69-1 has the greatest astaxanthin content (251.78 ± 0.27 μg/g DCW) and yield (1.8632 ± 0.0023 mg/L) among R. paludigena strains. The 18.78 Mbp R. mucilaginosa HL26-1 genome includes 5,711 protein-coding genes. Conversely, the R. paludigena LL69-1 genome was 20.99 Mbp, encompassing 6,782 predicted genes. A comprehensive investigation of draft genome sequences of these two strains identified CrtE, CrtYB, CrtI, CrtS, and CrtR as potential astaxanthin transcription genes. Conclusion: Here, our results highlight the outstanding potential of two naturally pigmented yeasts, R. mucilaginosa HL26-1 and R. paludigena LL69-1, for astaxanthin production. Furthermore, our findings provide information on the whole genome and protein-encoded genes associated with astaxanthin production, which serve as valuable biological resources for various biotechnological applications.
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Antimicrobial activity, genome analysis, and gene cluster encoding the plantaricin production of Lactiplantibacillus plantarum ZBK1-5
(2024-04-01)
Choovet, Natladda
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Jirakanjanasit, Thanadol
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Subphon, Punyavee
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Thepsombat, Supranee
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Kingkaew, Engkarat
This study aimed to explore bacteriocin-producing lactic acid bacteria (LAB), identify the genes influencing bacteriocin synthesis, and assess their probiotic potential via safety evaluations both in vitro and in silico. The strain ZBK1-5, isolated from pickled ginger, was identified as Lactiplantibacillus plantarum. The bacteriocin ZBK1-5 exhibited the highest antimicrobial activity with 6,400 AU/ml at 18 h, predominantly effective against Gram-positive bacteria and stable within pH 2–9. Significantly, the genome analysis confirmed the existence of bacteriocin synthesis genes, specifically plantaricin KJ, EF, A, and N. Simultaneously, the safety evaluations showed its low risk of antibiotic resistance gene transfer, thereby emphasizing the safety profile of the strain ZBK1-5. The genetic components associated with the ability of L. plantarum ZBK1-5 to survive and adapt in gastrointestinal conditions provide additional evidence (16 genes related to acid stress and 9 genes associated with bile resistance), supporting its potential as a probiotic candidate. These findings were validated through in vitro digestion conditions, where the viability of the cells was observed to be 68.26, 66.62, and 60.91% during transit through the oral, gastrointestinal, and small intestinal phases, respectively. Additionally, the strain ZBK1-5 showed a 90.39% adhesion rate in the Caco-2 cell line. The unique characteristics of plantaricin produced by L. plantarum ZBK1-5 exhibit potent antibacterial activity, rapid time to production compared to other known plantaricins, and strain safety for application and upscaling. This research study offers significant scientific insights into L. plantarum ZBK1-5, a plantaricin producer, emphasizing its promising potential for future applications.

Kingkaew, Engkarat

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