Bifidobacterium pseudocatenulatum ATCC 27919 exopolysaccharides induced autophagy and apoptosis against endoplasmic reticulum stress in Caco-2 cells

Aims@#This study aimed to investigate the effect of exopolysaccharide (EPS) from Bifidobacterium pseudocatenulatum ATCC 27919 in Caco-2 cells on apoptotic and autophagic pathways.@*Methodology and results@#Cell viability was examined by MTS assay and it showed a significant decrease in Caco-2 cells after exposure to EPS. Microscopy imaging and morphological analyses demonstrated that EPS-exposed Caco-2 cells exhibited the main morphological characteristics of apoptosis. EPS-exposed cells showed early apoptosis and cell cycle arrest at the G2/M phase in the cell cycle and dead cell assays. qPCR suggested that mRNA expression of substantial apoptotic markers such as cleaved Caspase-3, BAX and PARP-1 were significantly increased in EPS-exposed cells. The autophagy event was demonstrated in EPS-exposed cells by the contrary mRNA expression of Beclin-1 and Bcl-2 and the detection of autophagic LC3-II protein at 24 h exposure. GRP78 mRNA expression was also increased in EPS-exposed cells, indicating the occurrence of endoplasmic reticulum (ER) stress. @*Conclusion, significance and impact of study @#Autophagy activity in EPS-exposed Caco-2 cells preceded apoptosis, suggesting it was a cytoprotective response against ER stress. Research findings set the foundation for therapeutic CRC treatments and provide insight into its regulatory processes.

Optimization of Bifidobacterium pseudocatenulatum KAKii cultivation conditions for exopolysaccharide production by using response surface methodology

Aims@#Bifidobacteria is a non-motile, Gram-positive, strictly anaerobic and non-spore-forming bacteria that can produce exopolysaccharide (EPS). EPS is a polymer of sugars, long chained polysaccharide which have been shown to give benefit towards human health. The optimum conditions for EPS production by Bifidobacterium are still scarce. Therefore, a study was conducted to optimize the growth conditions (pH, temperature and cultivation time) for a better improvement of EPS production. @*Methodology and results@#Three Bifidobacterium strains were cultured and the highest EPS producing strain was selected for optimization. Response Surface Methodology (RSM) was used to optimize the growth conditions for a maximum EPS production. Subsequently, EPS was characterized by using FT-IR and GC-MS. Based on the result obtained, B. pseudocatenulatum KAKii had the highest EPS production compared to the other two strains namely B. pseudocatenulatum ATCC 27919 and B. animalis. Meanwhile, the optimization of the three factors towards selected strain found that EPS produced crucially depends on time of cultivation (23.59 h) other than pH (5.0) and temperature (34.75 °C). The validation showed that the predicted and experimental values were not significantly different (P > 0.05), indicating that the developed model is fitted well for the optimization. Meanwhile, FT-IR and GC-MS results showed that the EPS was composed of D-glucose, mannose, galactose, maltose and acetic acid as by-product. @*Conclusion, significance and impact of study@#This result showed that the EPS produced by B. pseudocatenulatum KAKii is from hetero-exopolysaccharide group with acetic acid as by-product made them a possible anticancer agent in future.

Isolation and identification of lactic acid bacteria from different stages of traditional Malaysian tempeh production

Aims: There are many methods of soybean tempeh production as they vary according to the producers. Isolation of lactic acid bacteria (LAB) from tempeh was carried out at different stages of the tempeh production to examine the occurrence of LAB and to identify the isolates. Methodology and results: Morphological, physiological and chemical characteristics with the use of API 20 Strep, API 50 CHL kit and 16S rRNA gene sequences were employed to identify LAB. By using API 20 Strep and API 50 CHL kit, fourteen LAB were obtained and twelve isolates have been successfully identified: seven coccus LAB isolates as Enterococcus faecium, four cocci-bacilli as Leuconostoc mesenteroides ssp. mesenteroides, one bacilli as Lactobacillus delbrueckii ssp. delbrueckii. Meanwhile, two bacilli isolates were categorised as unidentified strain. On the other hand, molecular identification using 27f and 1429r primer had revealed that L. mesenteroides and L. delbrueckii were identified as Leuconostoc lactis and Leuconostoc sp. respectively. Whereas, two previously unidentified bacilli isolates were identified as Alicyclobacillus sp. Conclusion, significance, and impact of study: This result shows that various types of LAB was detected at every stages of tempeh production and had been identified by using two different techniques. The unique characteristics of LAB offer their potential towards food and pharmaceutical industry.