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Bacillus clausii has been used as probiotic bacteria in dietary supplements because of its prominent probiotic activities including its multi-antibiotic resistance, digestive enzyme production, vitamin synthesis, and immunomodulatory effects. In this study, heat and acid-stability, acute and sub-acute toxicity were conducted to evaluate the stability and safety of liquid-suspension probiotics (LiveSpo® Clausy, LiveSpo Pharma) containing ≥ 2 billion spores/5 mL of Bacillus clausii ANA39 strain. The result showed that the B. clausii ANA39 spores were heat- and acid pH-stable with the remaining survival rate of 60% and 40% at treatment conditions of 80oC and pH 2.0 for 20 min, respectively. Acute toxicity data in mice indicated LD50 was not detectable, even at extremely high dosage of 2.4 x 1010 CFU/kg, indicating LiveSpo® Clausy was in unclassified category. The sub-acute toxicity results showed that the rabbits administrated with B. clausii ANA39 at the dosages of 0.93 mL/kg rabbit/day (equivalent to 0.37 x 109 CFU ANA39 spores/kg rabbit/day) and 2.80 mL/kg rabbit/day (equivalent to 1.12 x 109 CFU of B. clausii ANA39 spores/kg rabbit/day) were healthy and steadily gained weight without any abnormal physiology and anatomy. Thus, LiveSpo® Clausy is resistant to high temperatures and low pH acids, stable for at least 24 months at room temperature, and safe for use as food supplements.

Rice bran is a subsidised product of rice processing. It is rich in carbohydrate, especially xylan therefore, has being used for production of soluble fiber oligosaccharide including xylooligosaccharides (XOS). XOS is an oligomer of 2-7 xylose residues and has been proven to be fermented by beneficial bacteria Bifidobacterium and Lactobacillus in colon. The market for XOS is increasing rapidly due to its advantages in biological and technological properties, compared to other common oligosaccharides, such as fructooligosaccharide or galactooligosaccharide. XOS can be produced from rice bran using either chemical or enzymatic hydrolysation technologies. The hydrolyzation using β-1,4-xylanase is commonly used to produce XOS from rice bran. However, an appropriate technology for XOS production from rice bran with high purity and food safety in Vietnam is not available yet. This paper presents new data on optimisation of rice bran hydrolyzation by xylanase to produce XOS using the quadratic model of Box-Behnken. The theoretically optimized conditions for the hydrolyzation are 0.25% enzyme at pH 5.5, temperature of 50°C for 18 hours. Experimental data confirmed the selected condition. The XOS product contains mainly xylobiose, xylotriose and xylotetraose.

Pigmented spore-forming bacterial strains were isolated from the gastrointestinal tracts of chickens for screening for heat-stable carotenoid-producing strains that could be applied as feed supplements. Of the seven heat-stable pigmented isolates screened, only two, yellow Sporosarcina saromensis CH1 and red-orange Bacillus aquimaris CH9, produced pigments with typical carotenoid absorbance peaks (400–500 nm). The CH9 carotenoids exhibited higher scavenging activity (73.2%) of DPPH free radicals than the CH1 carotenoids (35.9%) and carotenoids of the reference B. indicus HU36 strain (78.4%), in comparison to 100% activity of acid ascorbic at 18.75 M as the standard. The CH9 strain produced high levels of carotenoids (439 g [g DW]-1) and formed nearly 100% spores, whereas the CH1 strain produced low levels of carotenoids (92 g [g DW]-1) and only achieved 30% sporulation. Chromatographic and spectral profiles of the carotenoids found in CH9 indicated the presence of as many as 11 different carotenoid types closely related to 1-HO-demethylspheroidene and keto/hydroxyl derivatives of  carotene. We successfully produced concentrated orange CH9 spore powder at a high concentration of 6.1 × 1011 CFU g-1; these spores were much more heat-stable (66% survival at 80°C for 20 min) than the reference B. indicus HU36 spores (9% survival at 50°C for 20 min). In conclusion, B. aquimaris CH9 is a promising probiotic carotenoid-producing strain, with heat-stable spores that should withstand the heat-treatment processing required for feed and food supplement production.