Qi Li

Bio: Qi Li is an academic researcher from Northwestern Polytechnical University. The author has contributed to research in topics: Interleukin 21 & Interleukin 12. The author has an hindex of 17, co-authored 39 publications receiving 779 citations. Previous affiliations of Qi Li include Northwestern Polytechnic University.

Biological activity of lipopeptides from Bacillus

Abstract: The lipopeptides of Bacillus are small metabolites that contain a cyclic structure formed by 7-10 amino acids (including 2-4 D-amino acids) and a beta-hydroxy fatty acid with 13-19 C atoms. These lipopeptides exhibit a variety of biological activities, including interactions with biofilms, and anti-fungal, anti-inflammatory, anti-tumor, anti-virus, and anti-platelet properties. The multiple activities of lipopeptides have stimulated significant interest in the exploitation of these lipopeptides for use as antibiotics, feed additives, anti-tumor agents, urgent thrombolytic therapeutic agents, and drug delivery systems. Understanding the natural function of these structurally diverse lipopeptides in Bacillus provides insight into microbial regulatory programs and is required for efficient development of more effective products. Currently, there is still insufficient knowledge of the direct target of these lipopeptides, and continued efforts are needed to enhance their biosynthesis efficiency for industrial applications.

Functional characterization and biotechnological potential of exopolysaccharide produced by Lactobacillus rhamnosus strains isolated from human breast milk

Abstract: Microbial exopolysaccharide (EPS) is currently developed as a potential biopolymer due to its unique characteristics, biological activity and safety. EPS of lactic acid bacteria that have been isolated from human breast milk were assumed to possess novel functions due to their uniqueness; however, they have not been extensively characterized before. In order to verify this hypothesis, the functional characterizations and biotechnological potential were conducted on EPSs produced by six Lactobacillus rhamnosus strains from human breast milk. After isolation and purification, the EPS from each strain was separately characterized in production and functional activities in vitro, including flocculating, emulsifying, solubility, antioxidant, antibacterial, and antitumor activities. As a result, the six strains yielded high EPS production (461–737 mg/l) after 48 h of incubation. The EPSs showed flocculating activity of 66–88% and an emulsifying activity of 23–45%. The EPSs varied in characteristics of solubility in water, oil binding, and water holding capacities. The EPSs showed potent antioxidant activity in analyses of hydroxyl radical (50–82%), DPPH radical (40–63%), superoxide anion radical (6–29%), and metal chelating activity (54–73%). Furthermore, the EPSs exhibited antitumor activity against Caco-2 cells (36–54%) at 600 μg/ml and strong antibacterial activities against E. coli (12–14.3 mm) and Salmonella typhimurium (10–13 mm), corresponding to excellent biofilm inhibition activity against S. typhimurium (58–71%) in vitro. The results indicated that the EPSs from Lactobacillus rhamnosus strains isolated from human breast milk have novel functions better than other reported ones, and thus have great potential in food, biomedicine, and pharmaceutics industries.

Anticancer potential against cervix cancer (HeLa) cell line of probiotic Lactobacillus casei and Lactobacillus paracasei strains isolated from human breast milk

Abstract: Lactic acid bacteria have been categorized as probiotics and play a crucial role in human health by stimulating the supply of nutrients, shaping the immune system, and preventing the colonization of pathogenic microbes. This study investigated the mechanisms for the action of three potential probiotic Lactobacillus strains: Lactobacillus casei SR1, Lactobacillus casei SR2, and Lactobacillus paracasei SR4 isolated from human breast milk. These Lactobacillus strains were identified via 16S DNA sequencing and characterized via biochemical assays including acid resistance, bile resistance, antioxidant activity, and antibiotic susceptibility. The bioactivity of the cell-free culture supernatant (CFCS) secreted by these strains on the cervix cancer (HeLa) cell line was also evaluated via cytotoxicity assay and apoptosis analysis. The mechanism of anticancer activity was also investigated via RT-qPCR and western blotting. The results demonstrated that these newly isolated Lactobacillus strains from human milk displayed noticeable probiotic characteristics such as excellent antibiotic susceptibility, outstanding antioxidant activity, and promising resistance to low pH and high concentration of bile salts. The results of the conducted bioactivity assays verified that the CFCSs had acceptable anticancer effects on cervix cancer (HeLa) cells by upregulating the expression of apoptotic genes BAX, BAD, caspase3, caspase8, and caspase9 and by downregulating the expression of the BCl-2 gene. Overall, these results indicate that the Lactobacillus strains isolated from human breast milk could be considered as a topical medication with a potential therapeutic index due to their efficacy against cervix cancer cells.

Biofilms in the Food Industry: Health Aspects and Control Methods

Abstract: Diverse microorganisms are able to grow on food matrixes and along food industry infrastructures. This growth may give rise to biofilms. This review summarizes, on the one hand, the current knowledge regarding the main bacterial species responsible for initial colonization, maturation and dispersal of food industry biofilms, as well as their associated health issues in dairy products, ready-to-eat foods and other food matrixes. These human pathogens include Bacillus cereus (which secretes toxins that can cause diarrhea and vomiting symptoms), Escherichia coli (which may include enterotoxigenic and even enterohemorrhagic strains), Listeria monocytogenes (a ubiquitous species in soil and water that can lead to abortion in pregnant women and other serious complications in children and the elderly), Salmonella enterica (which, when contaminating a food pipeline biofilm, may induce massive outbreaks and even death in children and elderly), and Staphylococcus aureus (known for its numerous enteric toxins). On the other hand, this review describes the currently available biofilm prevention and disruption methods in food factories, including steel surface modifications (such as nanoparticles with different metal oxides, nanocomposites, antimicrobial polymers, hydrogels or liposomes), cell-signaling inhibition strategies (such as lactic and citric acids), chemical treatments (such as ozone, quaternary ammonium compounds, NaOCl and other sanitizers), enzymatic disruption strategies (such as cellulases, proteases, glycosidases and DNAses), non-thermal plasma treatments, the use of bacteriophages (such as P100), bacteriocins (such us nisin), biosurfactants (such as lichenysin or surfactin) and plant essential oils (such as citral- or carvacrol-containing oils).

Carotenoids: biochemistry, pharmacology and treatment

Abstract: Carotenoids and retinoids have several similar biological activities such as antioxidant properties, the inhibition of malignant tumour growth and the induction of apoptosis. Supplementation with carotenoids can affect cell growth and modulate gene expression and immune responses. Epidemiological studies have shown a correlation between a high carotenoid intake in the diet with a reduced risk of breast, cervical, ovarian, colorectal cancers, and cardiovascular and eye diseases. Cancer chemoprevention by dietary carotenoids involves several mechanisms, including effects on gap junctional intercellular communication, growth factor signalling, cell cycle progression, differentiation‐related proteins, retinoid‐like receptors, antioxidant response element, nuclear receptors, AP‐1 transcriptional complex, the Wnt/β‐catenin pathway and inflammatory cytokines. Moreover, carotenoids can stimulate the proliferation of B‐ and T‐lymphocytes, the activity of macrophages and cytotoxic T‐cells, effector T‐cell function and the production of cytokines. Recently, the beneficial effects of carotenoid‐rich vegetables and fruits in health and in decreasing the risk of certain diseases has been attributed to the major carotenoids, β‐carotene, lycopene, lutein, zeaxanthin, crocin (/crocetin) and curcumin, due to their antioxidant effects. It is thought that carotenoids act in a time‐ and dose‐dependent manner. In this review, we briefly describe the biological and immunological activities of the main carotenoids used for the treatment of various diseases and their possible mechanisms of action.

Influence of Resveratrol on the Immune Response

Abstract: Resveratrol is the most well-known polyphenolic stilbenoid, present in grapes, mulberries, peanuts, rhubarb, and in several other plants. Resveratrol can play a beneficial role in the prevention and in the progression of chronic diseases related to inflammation such as diabetes, obesity, cardiovascular diseases, neurodegeneration, and cancers among other conditions. Moreover, resveratrol regulates immunity by interfering with immune cell regulation, proinflammatory cytokines’ synthesis, and gene expression. At the molecular level, it targets sirtuin, adenosine monophosphate kinase, nuclear factor-κB, inflammatory cytokines, anti-oxidant enzymes along with cellular processes such as gluconeogenesis, lipid metabolism, mitochondrial biogenesis, angiogenesis, and apoptosis. Resveratrol can suppress the toll-like receptor (TLR) and pro-inflammatory genes’ expression. The antioxidant activity of resveratrol and the ability to inhibit enzymes involved in the production of eicosanoids contribute to its anti-inflammation properties. The effects of this biologically active compound on the immune system are associated with widespread health benefits for different autoimmune and chronic inflammatory diseases. This review offers a systematic understanding of how resveratrol targets multiple inflammatory components and exerts immune-regulatory effects on immune cells.

Postbiotics-parabiotics: the new horizons in microbial biotherapy and functional foods

Abstract: Probiotics have several health benefits by modulating gut microbiome; however, techno-functional limitations such as viability controls have hampered their full potential applications in the food and pharmaceutical sectors. Therefore, the focus is gradually shifting from viable probiotic bacteria towards non-viable paraprobiotics and/or probiotics derived biomolecules, so-called postbiotics. Paraprobiotics and postbiotics are the emerging concepts in the functional foods field because they impart an array of health-promoting properties. Although, these terms are not well defined, however, for time being these terms have been defined as here. The postbiotics are the complex mixture of metabolic products secreted by probiotics in cell-free supernatants such as enzymes, secreted proteins, short chain fatty acids, vitamins, secreted biosurfactants, amino acids, peptides, organic acids, etc. While, the paraprobiotics are the inactivated microbial cells of probiotics (intact or ruptured containing cell components such as peptidoglycans, teichoic acids, surface proteins, etc.) or crude cell extracts (i.e. with complex chemical composition)”. However, in many instances postbiotics have been used for whole category of postbiotics and parabiotics. These elicit several advantages over probiotics like; (i) availability in their pure form, (ii) ease in production and storage, (iii) availability of production process for industrial-scale-up, (iv) specific mechanism of action, (v) better accessibility of Microbes Associated Molecular Pattern (MAMP) during recognition and interaction with Pattern Recognition Receptors (PRR) and (vi) more likely to trigger only the targeted responses by specific ligand-receptor interactions. The current review comprehensively summarizes and discussed various methodologies implied to extract, purify, and identification of paraprobiotic and postbiotic compounds and their potential health benefits.