Outdoor biohydrogen production by thermotolerant Rhodopseudomonas pentothenatexigens KKU-SN1/1 in a cluster of ten bioreactors system.

In tropical regions, the viability of outdoor photo-fermentative biohydrogen production faces challenges arising from elevated temperatures and varying light intensity. This research aimed to explore how high temperatures and outdoor environments impact both biohydrogen production and the growth of purple non-sulfur bacteria. Our findings revealed the potential of Rhodopseudomonas spp. as a robust outdoor hydrogen-producing bacteria, demonstrating its capacity to thrive and generate biohydrogen even at 40 °C and under fluctuating outdoor conditions. Rhodopseudomonas harwoodiae NM3/1-2 produced the highest cumulative biohydrogen of 223 mL/L under anaerobic light conditions at 40 °C, while Rhodopseudomonas harwoodiae 2M had the highest dry cell weight of 2.93 g/L. However, R. harwoodiae NM3/1-2 demonstrated the highest dry cell weight of 3.99 g/L and Rhodopseudomonas pentothenatexigens KKU-SN1/1 exhibited the highest cumulative biohydrogen production of 400 mL/L when grown outdoors. In addition, the outdoor enhancement of biohydrogen production was achieved through the utilization of a cluster of ten bioreactors system. The outcomes demonstrated a notable improvement in biohydrogen production efficiency, marked by the highest daily biohydrogen production of 493 mL/L d by R. pentothenatexigens KKU-SN1/1. Significantly, the highest biohydrogen production rate was noted to be 17 times greater than that observed in conventional batch production methods. This study is the first to utilize R. pentothenatexigens and R. harwoodiae for sustained biohydrogen production at high temperatures and in outdoor conditions over an extended operational period. The successful utilization of a clustered system of ten bioreactors demonstrates potential to scale-up for industrial biohydrogen production.

Alkaline Protease Production from Bacillus gibsonii 6BS15-4 Using Dairy Effluent and Its Characterization as a Laundry Detergent Additive.

Protease is a widely used enzyme particularly in the detergent industry. In this research, we aimed to isolate alkaline protease-producing bacteria for characterization as a laundry detergent additive. The screening of alkaline protease production was investigated on basal medium agar plus 1% skim milk at pH 11, with incubation at 30°C. The highest alkaline protease-producing bacterium was 6BS15-4 strain, identified as Bacillus gibsonii by 16S rRNA gene sequencing. While the optimum pH was 12.0, the strain was stable at pH range 7.0-12.0 when incubated at 45°C for 60 min. The alkaline protease produced by B. gibsonii 6BS15-4 using dairy effluent was characterized. The optimum temperature was 60°C and the enzyme was stable at 55°C when incubated at pH 11.0 for 60 min. Metal ions K+, Mg2+, Cu2+, Na+, and Zn2+ exhibited a slightly stimulatory effect on enzyme activity. The enzyme retained over 80% of its activity in the presence of Ca2+, Ba2+, and Mn2+. Thiol reagent and ethylenediaminetetraacetic acid did not inhibit the enzyme activity, whereas phenylmethylsulfonyl fluoride significantly inhibited the protease activity. The alkaline protease from B. gibsonii 6BS15-4 demonstrated efficiency in blood stain removal and could therefore be used as a detergent additive, with potential for various other industrial applications.

Diversity of fermentative yeasts with probiotic potential isolated from Thai fermented food products.

This research aimed to evaluate the diversity of yeasts recovered from fermented foods gathered from some areas of Northeastern Thailand. The fermented food items included Pla-som, Nham-pla, Kem-buknud, Isan-sausage, Pla-ra, Mhum-neu, Mhum-Khai-pla, Nham-neu, Nham-mu, Kung-joom, Som-pla-noi, and Poo-dong. Their probiotic characteristics were also investigated. A total of 103 yeast isolates of nine genera were identified using 28S rDNA sequencing. The yeast genera were Candida (20.3%), Diutina (2.9%), Filobasidium (1.0%), Kazachstania (33.0%), Pichia (3.9%), Saccharomyces (1.0%), Starmerella (28.2%), Torulaspora (2.9%), and Yarrowia (6.8%). Based on probiotic characteristic analysis of ten selected yeast strains, Kazachstania bulderi KKKS4-1 showed the strongest probiotic characteristics in terms of hemolytic activity, antimicrobial activity against pathogenic bacteria, tolerance to low pH and bile salt and hydrophobicity. Isolated yeasts with probiotic characteristics may be useful in fermented food and animal feed production to improve their nutritional values.

Candida konsanensis sp. nov., a new yeast species isolated from Jasminum adenophyllum in Thailand with potentially carboxymethyl cellulase-producing capability.

A new yeast species (KKU-FW10) belonging to the Candida genus was isolated from Jasminum adenophyllum in the Plant Genetic Conservation Project under The Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn area, Chulabhorn Dam, Konsan district within Chaiyaphum province in Thailand. The strain was identified via analysis of nucleotide sequences from the D1/D2 domain of 26S ribosomal DNA and based on its morphological, physiological and biochemical characteristics. The sequence obtained from yeast isolate KKU-FW10 was 97 percent identical to that of Candida chanthaburiensis (GenBank accession number AB500861.1), with 506/517 (nucleotides identity/total nucleotides) matching nucleotides, nine substitutions and two gaps being detected. This species belonged to the Candida clade. Regarding morphological characteristics, isolate KKU-FW10 presents cream-colored butyrous colonies, vegetative reproduction through budding and, round cells without filaments or ascospores. The major ubiquinone detected was Q-9. The above results suggest that isolate KKU-FW10 is a new member of the genus Candida, and the name Candida konsanensis is proposed for this yeast. The type strain of the new species is KKU-FW10(T) (= BCC 52588(T), = NBRC 109082(T), = CBS 12666(T)). In addition, this KKU-FW10 could potentially produce 58.24 Units/ml of carboxymethyl cellulase when it was cultured in YP broth containing 1.0 % carboxymethyl cellulose for 24 h.