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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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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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The Relationship between Microbial Communities in Coffee Fermentation and Aroma with Metabolite Attributes of Finished Products
(2024-08-01)
Todhanakasem, Tatsaporn
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Van Tai, Ngo
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Pornpukdeewattana, Soisuda
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Charoenrat, Theppanya
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Young, Briana M.
Coffee is a critical agricultural commodity and is used to produce premium beverages enjoyed by people worldwide. The microbiome of coffee beans has proven to be an essential tool that improves the flavor profile of coffee by creating aromatic flavor compounds through natural fermentation. This study investigated the natural microbial consortium during the wet process fermentation of coffee onsite in Thailand in order to identify the correlation between microbial diversity and biochemical characteristics including flavor, aroma, and metabolic attributes. Our study found 64 genera of bacteria and 59 genera of yeast/fungi present during the fermentation process. Group of microbes, mainly yeast and lactic acid bacteria, that predominated in the process were significantly correlated with preferable flavor and aroma compounds, including linalyl formate, linalool, cis-isoeugenol, trans-geraniol, and (-)-isopulegol. Some of the detected metabolites were found to be active compounds which could play a role in health.
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Enhancing small-scale acetification processes using adsorbed Acetobacter pasteurianus UMCC 2951 on κ-carrageenan-coated luffa sponge
(2024-01-01)
Sriphochanart, Wiramsri
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Krusong, Warawut
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Samuela, Nialmas
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Somboon, Pichayada
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Sirisomboon, Panmanas
Background. This study explored the utilization of luffa sponge (LS) in enhancing acetification processes. LS is known for having high porosity and specific surface area, and can provide a novel means of supporting the growth of acetic acid bacteria (AAB) to improve biomass yield and acetification rate, and thereby promote more efficient and sustainable vinegar production. Moreover, the promising potential of LS and luffa sponge coated with κ-carrageenan (LSK) means they may represent effective alternatives for the co-production of industrially valuable bioproducts, for example bacterial cellulose (BC) and acetic acid. Methods. LS and LSK were employed as adsorbents for Acetobacter pasteurianus UMCC 2951 in a submerged semi-continuous acetification process. Experiments were conducted under reciprocal shaking at 1 Hz and a temperature of 32 ◦C. The performance of the two systems (LS-AAB and LSK-AAB respectively) was evaluated based on cell dry weight (CDW), acetification rate, and BC biofilm formation. Results. The use of LS significantly increased the biomass yield during acetification, achieving a CDW of 3.34 mg/L versus the 0.91 mg/L obtained with planktonic cells. Coating LS with κ-carrageenan further enhanced yield, with a CDW of 4.45 mg/L. Acetification rates were also higher in the LSK-AAB system, reaching 3.33 ± 0.05 g/L d as opposed to 2.45 ± 0.05 g/L d for LS-AAB and 1.13 ± 0.05 g/L d for planktonic cells. Additionally, BC biofilm formation during the second operational cycle was more pronounced in the LSK-AAB system (37.0 ± 3.0 mg/L, as opposed to 25.0 ± 2.0 mg/L in LS-AAB). Conclusions. This study demonstrates that LS significantly improves the efficiency of the acetification process, particularly when enhanced with κ-carrageenan. The increased biomass yield, accelerated acetification, and enhanced BC biofilm formation highlight the potential of the LS-AAB system, and especially the LSK-AAB variant, in sustainable and effective vinegar production. These systems offer a promising approach for small-scale, semi-continuous acetification processes that aligns with eco-friendly practices and caters to specialized market needs. Finally, this innovative method facilitates the dual production of acetic acid and bacterial cellulose, with potential applications in biotechnological fields.

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