Kingkaew, Engkarat

Preferred name

Kingkaew, Engkarat

Main Affiliation

School of Science

engkarat.ki@kmitl.ac.th

Now showing 1 - 10 of 13

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Antioxidant Activity, γ-Aminobutyric Acid, and Genome Analysis of Lactiplantibacillus plantarum FL13-2 from Fermented Rice Flour
(2025-09-01)
Songsumanus, Apakorn
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Pinyosnit, Natawadee
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Kingkaew, Engkarat
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Panngeun, Thanapol
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Charunanthasunthon, Worasan
Ten rod-shaped isolates of lactic acid bacteria (LAB) from the traditional fermented rice flour, khao-khab were identified as belonging to the genus Lactobacillus based on phenotypic characteristics. Group I isolates (FL12-1, FL18-1, FL19-1S, FL23-1, FL24-1, FL25-1, and FL26-1) were closely related to Limosilactobacillus fermentum, exhibiting 16S rRNA gene sequence similarity of 99.4%–100%. Group II included FL13-2 and FL22-2 (Group IIA) and FL17B (Group IIB), closely related to Lactiplantibacillus plantarum (99.9%–100%) and Lactiplantibacillus pentosus (100%), respectively. All isolates demonstrated strong antioxidant potential, with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity—measured by the standard DPPH assay—ranging from 78.49±1.01% to 91.18±3.95%, surpassing that of ascorbic acid. Strain FL13-2, identified as L. plantarum through genomic analysis (Average Nucleotide Identity (ANI) 98.5%, digital DNA-DNA hybridization (dDDH) 92.5%), produced 2.43 g/L of γ-aminobutyric acid (GABA). It harbored key biosynthesis and transport genes (gadB, gadC, gatABCD, pdxK). Phylogenetic analysis confirmed high sequence similarity of these genes with other LAB strains, supporting their functional roles. The gad system was implicated in acid resistance and GABA production under low pH conditions. Genome annotation revealed bacteriocin genes (Enterocin X β, Plantaricin E, and F) and indicated low pathogenicity and absence of virulence factors. Antimicrobial resistance genes (vanH, vanT, vanY) were detected; however, these are intrinsic to LAB and associated with essential cell wall biosynthesis rather than acquired resistance. Additionally, the presence of the qacJ efflux pump and hlyIII gene—both commonly found in probiotic strains—further supports the safety profile of FL13-2. These findingshighlight L. plantarum FL13-2 as a promising multifunctional probiotic candidate with potent antioxidative, GABA-producing, and antimicrobial properties.
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Evaluating the safety and efficacy of Lacticaseibacillus paracasei TISTR 2593 as a therapeutic probiotic for obesity prevention
(2025-01-01)
Sitdhipol, Jaruwan
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Niwasabutra, Kanidta
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Chaiyawan, Neungnut
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Nuankham, Kamonsri
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Thanagornyothin, Thanaphol
Several recent studies have reported the potential of probiotics in reducing body weight and fat mass and improving glucose and lipid metabolism. Therefore, probiotic administration is considered an alternative approach for treating obesity. The objective of this study was to evaluate the probiotic properties and antiadipogenic potential of the strain TISTR 2593. Through whole-genome sequence analysis, the strain TISTR 2593 was identified as Lacticaseibacillus paracasei. L. paracasei TISTR 2593 exhibited γ-hemolytic activity (nonhemolysis) and demonstrated susceptibility to antibiotics, indicating that it is generally safe for consumption. Additionally, this strain displayed desirable probiotic properties, including tolerance to artificial gastric juice and bile salts, adhesion to Caco-2 cells, and the ability to inhibit pathogens. Furthermore, L. paracasei TISTR 2593 exhibited cholesterol-reducing capability and demonstrated antiadipogenic activity. In 3T3-L1 adipocytes, treatment with 10% (w/v) heated L. paracasei TISTR 2593 cells resulted in an approximately 50% reduction in lipid accumulation, similar to the positive control (quercetin). Moreover, L. paracasei TISTR 2593 heat-killed cells dose-dependently decreased the expression levels of CCAAT/enhancer-binding protein-α and peroxisome proliferator-activated receptor-γ, two vital transcription factors involved in the early stage of adipocyte differentiation. These findings suggest that L. paracasei TISTR 2593 possesses probiotic and functional properties, including antiadipogenic activity, supporting its potential as a therapeutic probiotic supplement for preventing obesity. Overall, the results of this study indicate that L. paracasei TISTR 2593 exhibits promising probiotic characteristics and beneficial effects on adipogenesis modulation, reinforcing its potential as a therapeutic option in obesity prevention.
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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
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Choovet, Natladda
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Booncharoen, Auttaporn
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Kingkaew, Engkarat
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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 T, 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 T 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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Lentilactobacillus terminaliae sp. nov., isolated from tree bark (Terminalia ivorensis Chev.) and its antioxidant activity
(2025-01-01)
Phuengjayaem, Sukanya
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Kingkaew, Engkarat
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Chamroensaksri, Nitcha
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Phongsopitanun, Wongsakorn
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Tanasupawat, Somboon
A Gram-stain-positive, facultatively anaerobic, rod-shaped strain, designated SPB1-3T, was isolated from tree bark. This strain exhibited heterofermentative production of dl-lactic acid from glucose. Optimal growth was observed at 25–40 °C, pH 4.0–7.0, and in the presence of 3% (w/v) NaCl. The cell wall peptidoglycan contained lysine and aspartic acid. The predominant fatty acids identified were C<inf>16:0</inf> and the Summed feature 7 (C<inf>19:1</inf> ω7c/C<inf>19:1</inf> ω6c and/or C<inf>19:1</inf> ω6c/ω7c/19cy). The polar lipid profile included phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol, along with two unidentified phospholipids, two unidentified amino lipids and two unidentified lipids. Phylogenetic analysis based on 16S rRNA gene sequences positioned strain SPB1-3T within the genus Lentilactobacillus, showing a close relation to Lentilactobacillus kosonis NBRC 111893T (99.86%) and Lentilactobacillus curieae CCTCC M 2011381T (98.65%). The whole genome of strain SPB1-3T comprised 1 932 998 base pairs with 1955 coding genes and a DNA G+C content of 37.8%. Digital DNA–DNA hybridization between strain SPB1-3T and closely related type strains ranged from 19.50 to 27.20%. The average nucleotide identity ranged from 84.21 to 85.56%, and the average amino acid identity ranged from 57.25 to 85.99%, both falling below the established thresholds for species delineation. Strain SPB1-3T was clearly distinguishable from related Lentilactobacillus species based on its phenotypic and chemotaxonomic char-acteristics, 16S rRNA gene sequence similarity and whole genome analysis. Additionally, the strain exhibited radical scavenging activity at 66.92% and demonstrated 82.32% inhibition in the tyrosinase inhibitory assay. These findings support the classification of strain SPB1-3T as a novel species within the genus Lentilactobacillus, for which the name Lentilactobacillus terminaliae sp. nov. is proposed. The type strain is SPB1-3T (=JCM 35081T=TISTR 10005T).
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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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Astaxanthin producing yeasts: Production and genomic analysis
(2024-09-16)
Kingkaew, Engkarat
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Phuengjayaem, Sukanya
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Tanasupawat, Somboon
This chapter explores yeasts and their potential in carotenoid production, delving into the diverse roles of carotenoids, their biosynthesis, and applications. Carotenoids, found in various organisms, serve several crucial functions, including light harvesting, photoprotection, and antioxidant activity. The focus shifts to astaxanthin, a red-orange carotenoid with immense market value and applications, notably in aquaculture and health. The astaxanthin-producing yeast strains emerge as a promising biotechnological platform for carotenoid production, particularly astaxanthin. Its unique features, FDA approval, and ability to synthesize carotenoids make it an ideal candidate for industrial applications. This chapter details the structure of astaxanthin and its biosynthetic pathway, emphasizing key genes involved. Additionally, it highlights other carotenoid producers and the biochemistry of astaxanthin. The latter part focuses on the health-promoting effects of astaxanthin, including antioxidant, anti-inflammatory, anti-diabetic, and anticancer activities. Immunomodulation benefits and the safety profile of astaxanthin are also discussed. The chapter concludes by addressing current trends, perspectives, and challenges in astaxanthin production, emphasizing the importance of circular, zero-waste processes.
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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 5001T. Whole-genome analysis indicated 82.54% similarity to R. ruineniae JCM 8097T, 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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Comparative genomic analysis and optimization of astaxanthin production of Rhodotorula paludigena TL35-5 and Rhodotorula sampaioana PL61-2
(2024-07-01)
Hoondee, Patcharaporn
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Phuengjayaem, Sukanya
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Kingkaew, Engkarat
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Rojsitthisak, Pornchai
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Sritularak, Boonchoo
Astaxanthin is a powerful antioxidant known to enhance skin, cardiovascular, eye, and brain health. In this study, the genome insights and astaxanthin production of two newly isolated astaxanthin-producing yeasts (TL35-5 and PL61-2) were evaluated and compared. Based on their phenotypic and genotypic characteristics, TL35-5 and PL61-2 were identified as basidiomycetous yeasts belonging to Rhodotorula paludigena and Rhodotorula sampaioana, respectively. To optimize astaxanthin production, the effects of cultural medium composition and cultivation conditions were examined. The optimal conditions for astaxanthin production in R. paludigena TL35-5 involved cultivation in AP medium containing 10 g/L glucose as the sole carbon source, supplemented with 1.92 g/L potassium nitrate, pH 6.5, and incubation at 20C for 3 days with shaking at 200 rpm. For R. sampaioana PL61-2, the optimal medium composition for astaxanthin production consisted of AP medium with 40 g/L glucose, supplemented with 0.67 g/L urea, pH 7.5, and the fermentation was carried out at 20C for 3 days with agitating at 200 rpm. Under their optimal conditions, R. paludigena TL35-5 and R. sampaioana PL61-2 gave the highest astaxanthin yields of 3.689 ± 0.031 and 4.680 ± 0.019 mg/ L, respectively. The genome of TL35-5 was 20,982,417 bp in length, with a GC content of 64.20%. A total of 6,789 protein-encoding genes were predicted. Similarly, the genome of PL61-2 was 21,374,169 bp long, with a GC content of 64.88%. It contained 6,802 predicted protein-encoding genes. Furthermore, all essential genes involved in astaxanthin biosynthesis, including CrtE, CrtYB, CrtI, CrtS, and CrtR, were identified in both R. paludigena TL35-5 and R. sampaioana PL61-2, providing evidence for their ability to produce astaxanthin.
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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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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.

Kingkaew, Engkarat

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