The effects of weightlessness on enteric microorganisms have been extensively studied, but have mainly been focused on pathogens. As a major component of the microbiome of the human intestinal tract, probiotics are important to keep the host healthy. Accordingly, understanding their changes under weightlessness conditions has substantial value. This study was carried out to investigate the characteristics of Lactobacillus acidophilus, a typical probiotic for humans, under simulated microgravity (SMG) conditions. The results revealed that SMG had no significant impact on the morphology of L. acidophilus, but markedly shortened its lag phase, enhanced its growth rate, acid tolerance ability up to pH < 2.5, and the bile resistance at the bile concentration of <0.05%. SMG also decreased the sensitivity of L. acidophilus to cefalexin, sulfur gentamicin, and sodium penicillin. No obvious effect of SMG was observed on the adhesion ability of L. acidophilus to Caco-2 cells. Moreover, after SMG treatment, both the culture of L. acidophilus and its liquid phase exhibited higher antibacterial activity against S. typhimurium and S. aureus in a time-dependent manner. The SMG treatment also increased the in vitro cholesterol-lowering ability of L. acidophilus by regulating the expression of the key cholesterol metabolism genes CYP7A1, ABCB11, LDLR, and HMGCR in the HepG2 cell line. Thus, the SMG treatment did have considerable influence on some biological activities and characteristics of L. acidophilus related to human health. These findings provided valuable information for understanding the influence of probiotics on human health under simulated microgravity conditions, at least.

•Seven Lactobacillus rhamnosus isolates were isolated from breast milk.•All selected isolates can survive under gastrointestinal conditions.•All isolates had high antimicrobial activity against three pathogenic bacteria.Breast milk is a source of lactic acid bacteria with remarkable functional and Technological properties; it is also a potential source of probiotics. In the present study, seven strains of Lactobacillus rhamnosus were isolated from breast milk and identified according to their 16S rDNA sequences. Furthermore, their probiotic potential was evaluated. The probiotic properties were tested for aspects of antibiotic susceptibility, antimicrobial activity, lysozyme tolerance, gut condition tolerance (low pH, bile salt tolerance, and 0.4% phenol resistance), hydrophobicity, antioxidant ability, aggregation ability, and adhesion to Caco-2. Most isolates were resistant to Streptomycin, Ampicillin, Gentamicin, Kanamycin, Penicillin, Cephalotoxin, and Ciprofloxacin. The isolate shows a strong ability to adhere to Caco-2 cells as well as DPPH radical scavenging activity in the range of 76%–85%. Isolates SHA113 and SHA117 showed a high survival rate under gastrointestinal tract conditions (>80%), indicating excellent potential for application as probiotics. The results of these tests indicate that the lactic acid bacteria isolated from human milk have excellent potential for use as probiotics in various products.

A substantial amount of emerging research is indicating that the gut microbiota has a significant impact on human health. Alterations of gut microbiota have clear consequences on intestinal homeostasis, physiology, gut microbiome, immune system and host metabolic pathways. Diet composition plays an important role in the control of gut microbial populations and, thus, in the prevention, management and treatment of certain diseases such as cancer, diabetes. A comprehensive analysis of previously reported results revealed that the gut microbiota can be modulated by diet and the composition of gut microbiota can be influenced by various diet components. The symbiotic relationship between different gut microbial communities regulates the immune system and, therefore, any dysbiosis can dysregulate the immune system. Further research is needed to fully understand the mechanisms involved in the interactions between diet composition, gut microbiota and associated diseases.

Lactic acid bacteria are associated with the human gastrointestinal tract. They are important for maintaining the balance of microflora in the human gut. An increasing number of published research reports in recent years have denoted the importance of producing interferon-gamma and IgA for treatment of disease. These agents can enhance the specific and nonspecific immune systems that are dependent on specific bacterial strains. The mechanisms of these effects were revealed in this investigation, where the cell walls of these bacteria were modulated by the cytokine pathways, while the whole bacterial cell mediated the host cell immune system and regulated the production of tumor necrosis factors and interleukins. A supplement of highly active lactic acid bacteria strains provided significant potential to enhance host’s immunity, offering prevention from many diseases including some cancers. This review summarizes the current understanding of the function of lactic acid bacteria immunity enhancement and cancer prevention.

In this work, cellulase was used to treat with oat bran, and its effect on the total polyphenol content and phenolic profiles were investigated, with heating-only treatment as the control. Antioxidant capacity of the phenolic extracts from oat bran was assessed by scavenging of 2,2′-azinobis (3-ethylbenzothiazoline-6- sulphonic acid), 2, 2-diphenyl-1-picrylhydrazyl radical cation, the ferric reducing antioxidant power, and protein oxidative damage protection assays. As a result, cellulase treatment significantly increased the total phenolic content, total antioxidant capacity, and the ability on the protection of protein from oxidative damage of the oat bran compared with heating-only treatment. Furthermore, cellulase treatment significantly increased availability of most phenolic compounds, except of gallic acid, such as caffeic acid by 97 % (5.33 vs. 10.51 μg g−1), vanillin by 28 % (3.32 vs. 4.24 μg g−1), p-coumaric acid by 105 % (5.55 vs. 11.35 μg g−1), and ferulic acid by 914 % (12.33 vs. 124.03 μg g−1). However, heating-only treatment had no significant influence on the five detected phenolic compounds. Therefore, the study revealed that cellulase treatment would produce polyphenol-rich oat products with increased antioxidant activity.

Trans-resveratrol (trans-3,5,4′-trihydroxystilbene) is one of the most promising stilbenes, a type of natural phenol that is produced naturally by some plant species in response to stress. Resveratrol exhibits multiple bioactivities and is used in the agriculture, medical, food, and cosmetic industries due to its antitumor, anti-inflammatory, cardioprotective, and antioxidant properties. Due to the increasing demand, an active area of investigation is the use of plant cell culture and metabolic engineering techniques to produce large quantities of active resveratrol. However, most recent studies have focused on the efficiency of synthesizing resveratrol in vitro, but have not investigated the contributions of the transcriptional activities of the genes encoding the related enzymes in the biosynthesis pathway. This article reviews recently developed methods for the biosynthesis of resveratrol and comprehensively reviews the current state of knowledge of the function of the key pathway enzymes in resveratrol synthesis. Approaches for enhancing resveratrol production, such as introducing non-pathway genes and co-localizing enzymes are described in detail.

As the unavoidable byproducts of alcoholic fermentation, higher alcohols are unhealthy compounds widespread in alcoholic drinks. To investigate the activity of apple crude enzymes toward higher alcohols in liquors, five kinds of apple peels, namely, Fuji, Gala, Golden Delicious, Red Star, and Jonagold, were chosen to prepare enzymes, and three kinds of Chinese liquors, namely, Xifeng (containing 45% ethanol), Taibai (containing 50% ethanol), and Erguotou (containing 56% ethanol), were tested. Enzymes were prepared in the forms of liquid solution, powder, and immobilized enzymes using sodium alginate (SA) and chitosan. The treatment was carried out at 37 °C for 1 h. The relative amounts of different alcohols (including ethanol, 1-propanol, isobutanol, 1-butanol, isoamylol, and 1-hexanol) were measured using gas chromatography (GC). Conditions for preparing SA-immobilized Fuji enzymes (SA-IEP) were optimized, and the obtained SA-IEP (containing 0.3 g of enzyme) was continuously used to treat Xifeng liquor eight times, 20 mL per time. Significant degradation rates (DRs) of higher alcohols were observed at different degrees, and it also showed enzyme specificity according to the apple varieties and enzyme preparations. After five repeated treatments, the DRs of the optimized Fuji SA-IEP remained 70% for 1-hexanol and >15% for other higher alcohols.