Xixi Zhao

The emergence of multi-drug resistant (MDR) pathogens greatly challenges the development of new drugs. Probiotics with the ability to inhibit MDR pathogens offer advantages over chemical antibiotics and drugs due to increased safety and fewer side effects. This study reports that Lactobacillus rhamnosus SHA113 (isolated from breast milk) significantly inhibited MDR Escherichia coli both in vitro and in vivo. MDR E. coli caused more severe inflammatory effects. TNF-α and IL-6 levels increased, while the IL-10 content decreased in serum. MDR E. coli caused disturbance in the gut microbial balance, increased the total coliform, decreased lactic acid bacteria in feces, decreased Firmicutes, and increased both Bacteroidetes and Proteobacteria. At the end of the curing treatment, ampicillin (AMP) treatment significantly reduced lactic acid bacteria compared to total coliform in feces and exacerbated the increase of Proteobacteria caused by MDR E. coli. L. rhamnosus SHA113 treatment resulted in a more significant and faster decrease of total coliform in feces and a significant decrease of Proteobacteria in the gut microbiota. The increase of total coliform in feces (caused by MDR E. coli infection) was positively correlated with IL-6 and TNF-α and negatively correlated with IL-10 in serum. However, the increase of lactic acid bacteria in feces (caused by L. rhamnosus SHA113 treatment) was negatively correlated with serum TNF-α, indicating that SHA113 exerted anti-inflammatory effects. These results suggest that L. rhamnosus SHA113 has great potential for inhibiting infections by MDR E. coli and for regulating the gut flora balance.

Two-dimensional (2D) cell culture is widely used to evaluate the potential of food compounds in anticancer activity in vitro. However, 3D culture is rarely used. In this study, we compared the obtained anticancer activity and mechanisms of iturin A, a multiple functional compound produced by Bacillus subtilis, in 2D and 3D cultures of HepG2 cells. 3D culture resulted in a much higher 50% inhibitory concentration (55.26 μM) compared to 2D culture (11.91 μM). Reactive oxygen species accumulation, autophagy, apoptosis characterized by cytochrome c release, high apoptotic protein expression and caspase activation were detected in both 2D and 3D cultures. Induction of paraptosis was also detected in 2D culture and the cytoplasmic vacuoles occurred in large numbers. Compared with 2D culture, 3D culture can simulate the microenvironment in vivo and provide more accurate data. Therefore, 3D culture was recommended for the evaluation of anticancer activity of food compounds towards solid tumors.

The iturin produced by Bacillus subtilis was previously found to exhibit significant antifungal activities, showing potential for application to food to protect it from spoilage and decay. However, its safe level must be evaluated before it can be used in foods consumed by mammals. Therefore, we carried out acute toxicity (7 days) and subacute toxicity (28 days) evaluations by intragastric administration of the iturin at 5000 mg per kg (bw) and 2000 mg per kg (bw) to Kunming mice. At the end of the subacute toxicity evaluation, the blood parameters of the mice were evaluated, and the visceral organs and intestinal flora were examined. No acute toxicity was found for 5000 mg per kg (bw) iturin and no significant negative effects were found for 2000 mg per kg (bw) iturin on blood parameters or organ functions. A more important observation was that the application of the iturin at the concentration of 2000 mg per kg (bw) showed great enhancement of the abundance of probiotics in the intestinal microflora. The iturin also showed inhibitory effects on cancer cells HepG2, Caco-2, MCF-7, A549, and BIU-87, at the level of 30 μM. The results indicate that the B. subtilis iturin has the potential to be developed as a functional food additive with antitumor potential and the capability to enhance the abundance of probiotics in the intestinal microflora. This study indicates a new possible source of functional food additives.

Phomopsis sp. XP-8, an endophytic fungus from the bark of Tu-Chung ( Eucommiaulmoides Oliv), revealed the pinoresinol diglucoside (PDG) biosynthetic pathway after precursor feeding measurements and genomic annotation. To verify the pathway more accurately, [ ¹³ C ₆ ]-labeled glucose and [ ¹³ C ₆ ]-labeled phenylalanine were separately fed to the strain as sole substrates and [ ¹³ C ₆ ]-labeled products were detected by ultra-high performance liquid chromatography-quantitative time of flight mass spectrometry. As results, [ ¹³ C ₆ ]-labeled phenylalanine was found as [ ¹³ C ₆ ]-cinnamylic acid and p -coumaric acid, and [ ¹³ C ₁₂ ]-labeled pinoresinol revealed that the pinoresinol benzene ring came from phenylalanine via the phenylpropane pathway. [ ¹³ C ₆ ]-Labeled cinnamylic acid and p -coumaric acid, [ ¹³ C ₁₂ ]-labeled pinoresinol, [ ¹³ C ₁₈ ]-labeled pinoresinol monoglucoside (PMG), and [ ¹³ C ₁₈ ]-labeled PDG products were found when [ ¹³ C ₆ ]-labeled glucose was used, demonstrating that the benzene ring and glucoside of PDG originated from glucose. It was also determined that PMG was not the direct precursor of PDG in the biosynthetic pathway. The study verified the occurrence of the plant-like phenylalanine and lignan biosynthetic pathway in fungi. Importance: Verify the phenylpropanoid-pinoresinol biosynthetic pathway and its glycosides in an endophytic fungi.