Preliminary study on the active substances and cellular pathways of lactic acid bacteria for colorectal cancer treatment.

Colorectal cancer (CRC) is a common malignant tumor and is one of the three most common cancers worldwide. Traditional surgical treatment, supplemented by chemotherapy and radiotherapy, has obvious side effects on patients. Immunotherapy may lead to some unpredictable complications. Low introduction rate and high cost are some of the problems of gene therapy, so finding a safe, reliable and least toxic treatment method became the main research direction for this study. Lactic acid bacteria and their metabolites are widely used in functional foods or as adjuvant therapies for various diseases because they are safe to eat and have no adverse reactions. Research has shown that lactic acid bacteria and their metabolites play an auxiliary therapeutic role in colorectal cancer mainly by improving the intestinal flora composition, inhibiting the growth of pathogenic bacteria and inhibiting the proliferation of cancer cells. It is now widely believed that the substances that probiotics such as lactic acid bacteria exert anti-cancer effects are mainly secondary metabolites such as butyric acid. Lb. plantarum AY01 isolated from fermented food has good anti-cancer ability, and its main anti-cancer substance is 2'-deoxyinosine. Through flow cytometry detection, it was found that Lb. plantarum AY01 can block cell proliferation in the S phase. In addition, Lb. plantarum AY01 culture reduces the sensitivity of mice to colitis-associated CRC induced by azoxymethane (AOM)/dextran sulfate sodium salt (DSS) and exhibits the occurrence and promotion of tumors. According to transcriptome analysis, Lb. plantarum AY01 may induce apoptosis of colorectal cancer cells by activating the p38 MAPK pathway. This experiment provided possibilities for the treatment of CRC.

Mechanical properties and wound healing potential of bacterial cellulose-xyloglucan-dextran hydrogels.

Bacterial cellulose (BC) is a promising material for use as an artificial skin in wound healing application, however, its applications are limited due to its poor malleability. Incorporating non-cellulosic polysaccharides such as dextran and xyloglucan (XG) may enhance its respective wound healing and malleability. This study presents a novel in situ biopreparation method to produce BC-based hybrid hydrogels containing dextran (BC-D) and xyloglucan-dextran (BC-XG-D) with unique mechanical and rheological properties. Structural analysis revealed that dextran of different sizes (10 k, 70 k and 2 M of Mw) form micron-sized particles by loosely binding to cellulosic fibres. The addition of xyloglucan resulted acts as a lubricant in mechanical testing. The BC-XG-D hybrid hydrogels showed a reduced Young's modulus of 4 MPa and a higher maximum tensile strain of 53 % compared to native BC. Moreover, they displayed less plastic but more viscous behaviour under large shear strain deformation. The wound healing animal model experiments demonstrated that the BC-XG-D hybrid hydrogels promoted wound healing process and skin maturation. Overall, these findings contribute to the development of functional BC-based medical materials with desired mechanical and rheological properties that have the potential to accelerate wound healing.

The comparison of microbial communities in thyroid tissues from thyroid carcinoma patients.

Thyroid carcinoma is a common endocrine organ cancer associated with abnormal hormone secretion, leading to the disorder of metabolism. The intestinal microbiota is vital to maintain digestive and immunologic homeostasis. The relevant information of the microbial community in the gut and thyroid, including composition, structure, and relationship, is unclear in thyroid carcinoma patients. A total of 93 samples from 25 patients were included in this study. The results showed that microbial communities existed in thyroid tissue; gut and thyroid had high abundance of facultative anaerobes from the Proteobacteria phyla. The microbial metabolism from the thyroid and gut may be affected by the thyroid carcinoma cells. The cooccurrence network showed that the margins of different thyroid tissues were unique areas with more competition; the stabilization of microcommunities from tissue and stool may be maintained by several clusters of species that may execute different vital metabolism processes dominantly that are attributed to the microenvironment of cancer.

The influence of alkaline treatment on the mechanical and structural properties of bacterial cellulose.

The unique mechanical properties of hydrated bacterial cellulose make it suitable for biomedical applications. This study evaluates the effect of concentrated sodium hydroxide treatment on the structural and mechanical properties of bacterial cellulose hydrogels using rheological, tensile, and compression tests combined with mathematical modelling. Bacterial cellulose hydrogels show a concentration-dependent and irreversible reduction in shear moduli, compression, and tensile strength after alkaline treatment. Applying a poroelastic biphasic model to through-thickness compressive stress-relaxation tests showed the alkaline treatment to induce no significant change in axial compression, an effect was observed in the radial direction, potentially due to the escape of water from within the hydrogel. Scanning electron microscopy showed a more porous structure of bacterial cellulose. These results show how concentration-dependent alkaline treatment induces selective weakening of intramolecular interactions between cellulose fibres, allowing the opportunity to precisely tune the mechanical properties for specific biomedical application, e.g., faster-degradable materials.

Effect of pH Buffer and Carbon Metabolism on the Yield and Mechanical Properties of Bacterial Cellulose Produced by Komagataeibacter hansenii ATCC 53582.

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.

Effect of lyophilization on the bacterial cellulose produced by different Komagataeibacter strains to adsorb epicatechin.

Bacterial cellulose (BC) has been widely used as a model system to investigate the interaction of polyphenols with the polysaccharides of cell walls. In this study, the water absorption ability and the adsorption ability of epicatechin of the never-dried and freeze-dried BC produced by a high-yield Komagataeibacter hansenii strain ATCC 53582 was compared with two normal-yield strains. The structural characteristics of BC were investigated via microscopy observation and mechanical/rheological tests. The 1-butyl-3-methylimidazolium acetate/dimethyl sulfoxide ([BMIM]Ac/DMSO) co-solvent was used to dissolve BC to calculate the degree of polymerization (DP). Results showed that compared with the other two strain, the BC synthesised by ATCC 53582 had a higher cellulose concentration (1.2 wt%) but lower epicatechin adsorption (29 µg/mg under 4 mM, pH 7). Its fibril network collapsed and led to a reduced recovery ratio (86 %) in the compression-relaxation test, which may be due to large DP (2856).