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High-cell-density culture for recombinant xylanase production and its application in hydrolysis of mild alkaline pretreated rice straw for xylooligosaccharide production
(2026-08-01)
Laemthong, Tunyaboon
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Sukhumsirichart, Wasana
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Chittapun, Supenya
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Kongsinkaew, Chatchol
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Satipattarn, Atikant
Rice straw is an abundant lignocellulosic residue whose effective utilization requires coordinated enzyme performance and pretreatment conditions. In this study, recombinant xylanase production was integrated with mild alkaline pretreatment to enable efficient conversion of rice straw into xylooligosaccharides (XOS). Recombinant xylanase was produced by Escherichia coli using high-cell-density fed-batch cultivation, achieving a maximum activity of 207.95 U/mL in an enriched synthetic medium. Alkaline pretreatment was optimized using response surface methodology, identifying 6.75% (w/v) biomass loading, 193.17 mM NaOH, and 20 min as conditions that balanced solid recovery with sugar release during subsequent enzymatic hydrolysis. Hydrolysis of the pretreated rice straw yielded 6.13 mg/mL total XOS, mainly xylotriose (X3, 2.73 mg/mL; 44.56%), xylobiose (X2, 2.00 mg/mL; 32.62%), and xylotetraose (X4, 1.02 mg/mL; 16.57%), with only minor amounts of xylose and xylopentaose detected. The combined X2 and X3 fractions accounted for 77.18% of the total XOS. XOS with degrees of polymerization of 2–4 are recognized as effective prebiotics, particularly for beneficial intestinal bacteria such as Bifidobacterium spp. Overall, linking recombinant enzyme production with alkaline pretreatment improved conversion consistency and supported efficient XOS production from rice straw.
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Valorizing Red Seaweed Spent Biomass into Reducing Sugars for β-Carotene Production by Rhodotorula paludigena
(2026-05-01)
Kongsinkaew, Chatchol
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Tangsattayatithan, Chutipol
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Chittapun, Supenya
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Phiphatbunyabhorn, Parivat
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Laemthong, Tunyaboon
Seaweed bioactive extraction generates de-extracted residual solids that remain carbohydrate-rich but are often underutilized. This study developed an integrated valorization route for Gracilaria fisheri spent biomass to produce fermentable sugars for β-carotene production by Rhodotorula paludigena CM33. Reducing sugar production was optimized using response surface methodology (Box–Behnken design) by varying reaction time, sulfuric acid concentration, and biomass loading at 90 °C. The predicted optimum (47.39 min, 2.50% (w/v) H<inf>2</inf>SO<inf>4</inf>, and 7.13% (w/v) biomass) yielded 22.41 g/L reducing sugars and was validated experimentally at 22.22 ± 0.19 g/L, indicating that the model reliably predicted reducing sugar production. The optimized condition was scaled up in a 22 L bioreactor with sequential acid hydrolysis followed by enzyme-assisted hydrolysis, increasing reducing sugars from ~30 to ~40 g/L. FTIR and SEM analyses indicated progressive modification of the carbohydrate matrix across processing stages. Batch cultivation of R. paludigena on the hydrolysate showed that ammonium sulfate supplementation significantly increased biomass, whereas β-carotene titers were not significantly different. Repeated-batch operation on non-supplemented hydrolysate sustained production over four cycles with β-carotene titers of 13.75–17.27 mg/L, demonstrating the operational feasibility of the hydrolysate-based system. Overall, this work demonstrates a practical seaweed biorefinery approach to upgrade G. fisheri spent biomass into sugars and carotenoid-rich yeast biomass.
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Fed-batch strategies for growing β-carotene enriched yeast Rhodotorula paludigena using untreated molasses
(2025-11-01)
Kongsinkaew, Chatchol
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Chisti, Yusuf
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Ketudat-Cairns, Mariena
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Chittapun, Supenya
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Pornpukdeewattana, Soisuda
The β-carotene-rich yeast Rhodotorula paludigena CM33 was grown in a 22-L bioreactor using sugarcane molasses in combination with several distinct fed-batch strategies: DO (dissolved oxygen)-stat; stepwise feeding; and hybrid feeding (an initial exponential feeding phase followed by a DO-stat operation). The impacts of feeding strategies on biomass production, carotenoid production and nutrient conversion efficiencies were evaluated. The stepwise feeding proved most effective, achieving: a final dry biomass concentration of 73.1 ± 2.7 g L−1; a β-carotene titer of 181.9 ± 1.0 mg L−1; a biomass volumetric productivity of 1.33 ± 0.05 g L−1 h−1; and β-carotene productivity of 3.31 ± 0.02 mg L−1 h−1. However, with this feeding strategy the sugar and nitrogen conversion efficiencies were the lowest: the β-carotene yield on total sugar was 0.92 ± 0.00 mg g−1 and its yield on nitrogen was 5.47 ± 0.06 mg g−1. In contrast, the DO-stat operation was the most resource efficient, providing a biomass yield on sugar of 0.47 ± 0.02 g g−1, a biomass yield on nitrogen of 2.64 ± 0.05 g g−1, a β-carotene yield on sugar of 1.08 ± 0.04 mg g−1, and β-carotene yield on nitrogen of 6.08 ± 0.08 mg g−1. The hybrid strategy resulted in intermediate values of the various performance parameters. Raw sugarcane molasses proved to be excellent for high-cell-density culture of R. paludigena. A compromise between productivity and resource use efficiency may be required for commercial production of β-carotene especially if the substrate is expensive compared to the product.
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Natural versus Saccharomyces boulardii self-induced anaerobic coffee fermentation: Effects on physicochemical properties and microbial ecology, and their influence on volatile profiles and sensory attributes across roast levels
(2025-10-01)
Pholtaisong, Jatuphol
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Kongsinkaew, Chatchol
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On-Mee, Thapanut
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Chittapun, Supenya
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Pornpukdeewattana, Soisuda
This study investigates the effects of natural self-induced anaerobic fermentation (NSIAF) and Saccharomyces boulardii self-induced anaerobic fermentation (SSIAF) on Arabica coffee during wet processing. Over 24 h of fermentation, NSIAF exhibited greater microbial diversity, higher titratable acidity, and increased reducing sugar consumption, while SSIAF provided a more controlled microbial environment dominated by S. boulardii. Volatile compound analysis identified 207 compounds, with lighter roasts showing the greatest number of significantly different compounds between NSIAF and SSIAF treatments. Sensory evaluation revealed a higher cupping score for NSIAF at a light roast (82.08 ± 0.14) compared to SSIAF (81.58 ± 0.14), reflecting distinct flavor characteristics imparted by each fermentation process. Both methods achieved specialty coffee standards (≥80 points), highlighting the potential of NSIAF for complex and diverse profiles and the suitability of SSIAF for consistency and controlled fermentation.
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Enhancing Biomass and Lipid Production in Messastrum gracile Using Inorganic Carbon Substrates and Alternative Solvents for Lipid Extraction
(2025-03-01)
Pan-utai, Wanida
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Pornpukdeewattana, Soisuda
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Inrung, Wilasinee
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Thurakit, Theera
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Srinophakun, Penjit
Microalgae show promise as a biomass and bioproduct for applications in various industries. The cultivation of microalgae plays a crucial role in optimizing biomass yield and bioproduct accumulation. The provision of inorganic carbon substrates substantially enhances microalgal growth and lipid biosynthesis, resulting in marked increases in the production of biofuels and other bioproducts. This study examined biomass and lipid accumulation in Messastrum gracile IFRPD 1061 under inorganic stress conditions, previously unreported. M. gracile IFRPD 1061 was subjected to varying conditions of inorganic carbon substrates, 1–3 g·L−1 sodium carbonate and bicarbonate concentration, to enhance biomass and lipid accumulation. Optimal productivity levels were observed with sodium bicarbonate addition of 3 g·L−1 and 1 g·L−1 for biomass and lipids, resulting in productivities of 392.64 and 53.57 mg·L−1·d−1, respectively. Results underlined the effectiveness of sodium carbonate and bicarbonate as inorganic carbon sources for stimulating microalgal growth and enhancing the production of high-value products. The extraction of lipids from freeze-dried biomass of M. gracile IFRPD 1061 demonstrated optimal yield using methanol/hexane solvents compared with the control experiments. Lipid extraction yields using methanol/hexane were 42.18% and 46.81% from oven-dried and freeze-dried biomass, respectively. Lipids extracted from oven-dried M. gracile IFRPD 1061 using methanol/hexane/chloroform solvents indicated the potential of methanol/hexane as a solvent for lipid extraction from dry microalgal biomass using an ultrasonic-assisted technique. This study contributes valuable insights into maximizing biofuel and bioproduct production from microalgae, highlighting A. gracilis as a promising candidate for industrial applications.
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Thermal degradation kinetics and purification of C-phycocyanin from thermophilic and mesophilic cyanobacteria
(2025-02-01)
Chittapun, Supenya
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Suwanmanee, Kattiya
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Kongsinkaew, Chatchol
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Pornpukdeewattana, Soisuda
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Chisti, Yusuf
The natural blue colorant C-phycocyanin (C-PC) has many potential applications but its poor heat stability limits its commercial use. This study compares the production and thermal stability of C-PC from two cyanobacteria: the thermophilic Thermosynechococcus sp. TUBT-T01 and the mesophilic Synechococcus cedrorum TISTR8589. Thermosynechococcus sp. produced nearly 1.9-fold more C-PC than S. cedrorum. Batch adsorption using a chromatographic cationic ion exchange resin (Streamline Direct HST1) was used to effectively purify the C-PC. The equilibrium adsorption capacity (Q<inf>eq</inf>) of the resin for C-PC was the highest at pH 5. At this pH, the Q<inf>eq</inf> for the thermophilic C-PC was 5.5 ± 0.1 mg mL⁻¹, whereas for the mesophilic C-PC it was 1.5 ± 0.2 mg mL⁻¹. Purification increased the concentration of the thermophilic C-PC by 5.9-fold, and that of mesophilic C-PC by 4.2-fold. The purity ratios of the final products from the two cyanobacteria were similar at ∼2.2. At 60 °C and pH 7, the C-PC of Thermosynechococcus sp. had ∼12-times longer half-life than the mesophilic C-PC; however, the productivity of the thermophilic C-PC was comparatively low because of a low biomass productivity of Thermosynechococcus sp.
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Enhanced high β-carotene yeast cell production by Rhodotorula paludigena CM33 and in vitro digestibility in aquatic animals
(2024-12-01)
Thumkasem, Namphet
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On-mee, Thapanut
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Kongsinkaew, Chatchol
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Chittapun, Supenya
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Pornpukdeewattana, Soisuda
This study assessed Rhodotorula paludigena CM33's growth and β-carotene production in a 22-L bioreactor for potential use as an aquatic animal feed supplement. Optimizing the feed medium's micronutrient concentration for high-cell-density fed-batch cultivation using glucose as the carbon source yielded biomass of 89.84 g/L and β-carotene concentration of 251.64 mg/L. Notably, using sucrose as the carbon source in feed medium outperforms glucose feeds, resulting in a β-carotene concentration of 285.00 mg/L with a similar biomass of 87.78 g/L. In the fed-batch fermentation using Sucrose Feed Medium, R. paludigena CM33 exhibited high biomass production rates (Q<inf>x</inf>) of 0.91 g/L.h and remarkable β-carotene production rates (Q<inf>p</inf>) of 2.97 mg/L.h. In vitro digestibility assays showed that R. paludigena CM33, especially when cultivated using sucrose, enhances protein digestibility affirming its suitability as an aquatic feed supplement. Furthermore, R. paludigena CM33's nutrient-rich profile and probiotic potential make it an attractive option for aquatic nutrition. This research highlights the importance of cost-effective carbon sources in large-scale β-carotene production for aquatic animal nutrition.
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Large-scale production of paraprobiotic soy milk in stirred tank bioreactor: A dual-step fermentation approach
(2024-12-01)
Kongsinkaew, Chatchol
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Hongphankul, Kant
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Soontornkitlert, Thanakorn
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Surarit, Worawat
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Sutheerawattananonda, Manote
This study investigates the feasibility of using soy milk as a substrate for cultivating Lactobacillus casei and its subsequent conversion into paraprobiotics. The research focuses on optimizing the fermentation process from shake flasks to bioreactor scale and assessing the antioxidant properties and proximate compositions of the resulting paraprobiotic soy milk beverage. The study highlights a dual-step large-scale fermentation process comprising an anaerobic fermentation step followed by a thermal inactivation step using the in situ temperature control system of the bioreactor. Results indicated that soy milk enriched with 10 g/L glucose and fermented at 37 °C for 24 h on flask scale provided optimal conditions for L. casei growth, achieving a bacterial count increase of 8.80 ± 0.11 log CFU/mL and a titratable acidity of 0.89 ± 0.03 %. These optimal conditions were employed for bioreactor scale fermentation, attaining a bacterial count of 10.02 ± 0.06 log CFU/mL and a titratable acidity of 1.07 ± 0.04 % at 24 h. The thermal inactivation step at 90 °C for 30 min successfully converted the probiotic soy milk into a paraprobiotic form, maintaining its antioxidant activity at 62.12 ± 2.58 % radical scavenging activity. The final paraprobiotic product met the Food and Drug Administration (FDA) specifications for titratable acidity, presenting a viable alternative for soy-based functional beverages.
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Shelf-life extension of Thai green papaya salad dressing by hurdle technology
(2024-09-01)
Sriphochanart, Wiramsri
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Krusong, Warawut
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Pornchaloempong, Pimpen
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Chotigavin, Natthaporn
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Srisawat, Kraisuwit
Green papaya salad or Som Tum is the most popular spicy mixed salads in Thailand due to its unique rich flavor. Green papaya salad dressing (GPSD) is made from various ingredients such as fresh chili pepper, fresh garlic, rind tamarind, fish sauce and lime oil, including the limitation in controlling the taste and flavor of salad dressing and its poor shelf-life. In this study, a convenient ready-to-eat GPSD was developed. Hurdle technology was applied to extend shelf-life of the GPSD based on monitoring of microbial contamination and food pathogens throughout the process. Hurdle technology able to decrease total plate count (TPC) from 5.6 ± 0.2 to 1 ± 0.3 log CFU/g and yeast and mold (Y&M) from 4.2 ± 0.3 to <1 log CFU/g. After 12 weeks of storage at 5 ± 2 °C, slightly increase of TPC was detected as 1.5 ± 0.2 log CFU/g and no changes were found for Y&M and other pathogens. At week 12, GPSD stored at 32 ± 2 °C was found to have higher TPC and Y&M (3.7 ± 0.3 and 2.4 ± 0.3 log CFU/g, respectively). Therefore, a combination of hurdles that combines low a<inf>w</inf>, low pH, heat treatment, low temperature after hot filling, and chilled storage could extend the shelf-life of GPSD with satisfy sensorial test result and be suitable for minimally processed salad dressing.
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Physicochemical, Nutritional, and Antioxidant Properties of Traditionally Fermented Thai Vegetables: A Promising Functional Plant-Based Food
(2024-09-01)
Pan-utai, Wanida
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Settachaimongkon, Sarn
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La-ongkham, Orawan
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Pornpukdeewattana, Soisuda
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Hamwane, Marisa
Fermented plant-based products were gathered from various regions in Thailand and categorized into 10 types of traditional commercial vegetables. Different vegetable materials and natural fermentation methods influence the diverse physical, chemical, nutritional, and functional attributes of the products. All the traditionally fermented Thai vegetable samples collected showed physicochemical properties associated with the fermentation process, contributing to the nutritional and functional quality of the final products. Achieving consistent research results is challenging due to the intricate nature of food matrices and biochemical processes during fermentation. The roles of microorganisms, especially probiotics, are crucial in delivering health benefits through fermented foods. Traditionally fermented Thai vegetable foods contain high levels of total soluble solids, titratable acidity, and salinity in pickled shallot and ginger as a result of the natural fermentation process and the ingredients used. The research findings were confirmed using a hierarchical cluster analysis (HCA)-derived dendrogram pattern. The nutritional compositions, total phenolic contents, and antioxidant activities varied among the different types of vegetables. The correlations among lipid, protein, fiber, total soluble solid (TSSs), total titratable acidity (TTA), and salinity as potential biomarkers in fermented vegetable products were examined. The results suggest that traditionally fermented Thai vegetable products significantly impacted food research by enhancing the quality and preserving the authenticity of traditionally fermented Thai vegetables.

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