Potential Of Cell-free Supernatants Research Articles

Anti-biofilm and anti-virulence potential of cell free supernatant of Akkermansia muciniphila against Salmonella

Anti-biofilm and anti-virulence potential of cell free supernatant of <em>Akkermansia muciniphila</em> against <em>Salmonella</em>

Assessment of therapeutic potential of Cell free supernatant of Pediococcus acidilactici NCDC 252: a novel potential probiotic of dairy origin

Health promoting activities of probiotics are attributed to probiotic-derived probioceuticals. These are biologically active metabolites that enhance human health either by augmenting human immunity or by inhibiting/neutralizing pathogens. Antimicrobial, antimalarial and anticancer potential of cell free supernatant (CFS) of NCDC 252 was studied using standard assays, CFS exhibited strong antimicrobial activity against studied pathogenic microbes. Neutralization studies confirmed the presence of organic acids in CFS. Enzymatic treatment of CFS revealed ITS proteinous nature. CFS also prevented biofilm formation by pathogens, exhibited antiplasmodial activity and revealed cytotoxicity against colon cancer cells. All these activities suggest a spectrum of beneficial effects of NCDC 252 mediated through CFS. Isolation of active principle will help in selective therapeutic use of NCDC 252.

Potential of Cell-Free Supernatant from Lactobacillus plantarum NIBR97, Including Novel Bacteriocins, as a Natural Alternative to Chemical Disinfectants.

The recent pandemic of coronavirus disease 2019 (COVID-19) has increased demand for chemical disinfectants, which can be potentially hazardous to users. Here, we suggest that the cell-free supernatant from Lactobacillus plantarum NIBR97, including novel bacteriocins, has potential as a natural alternative to chemical disinfectants. It exhibits significant antibacterial activities against a broad range of pathogens, and was observed by scanning electron microscopy (SEM) to cause cellular lysis through pore formation in bacterial membranes, implying that its antibacterial activity may be mediated by peptides or proteins and supported by proteinase K treatment. It also showed significant antiviral activities against HIV-based lentivirus and influenza A/H3N2, causing lentiviral lysis through envelope collapse. Furthermore, whole-genome sequencing revealed that NIBR97 has diverse antimicrobial peptides, and among them are five novel bacteriocins, designated as plantaricin 1 to 5. Plantaricin 3 and 5 in particular showed both antibacterial and antiviral activities. SEM revealed that plantaricin 3 causes direct damage to both bacterial membranes and viral envelopes, while plantaricin 5 damaged only bacterial membranes, implying different antiviral mechanisms. Our data suggest that the cell-free supernatant from L. plantarum NIBR97, including novel bacteriocins, is potentially useful as a natural alternative to chemical disinfectants.

Associations between the vaginal microbiome and Candida colonization in women of reproductive age

The composition of bacteria within the vaginal microbiome has garnered a lot of recent attention and has been associated with reproductive health and disease. Despite the common occurrence of yeast (primarily Candida) within the vaginal microbiome, there is still an incomplete picture of relationships between yeast and bacteria (especially lactobacilli), as well as how such associations are governed. Such relationships could be important to a more holistic understanding of the vaginal microbiome and its connection to reproductive health. The objective of the study was to perform molecular characterization of clinical specimens to define associations between vaginal bacteria (especially Lactobacillus species) and Candida colonization. Invitro studies were conducted to test the 2 most common dominant Lactobacillus species (Lactobacillus crispatus and Lactobacillus iners) in their ability to inhibit Candida growth and to examine the basis for such inhibition. A nested cross-sectional study of reproductive-age women from the Contraceptive CHOICE Project was conducted. Vaginal swabs from 299 women were selected to balance race and bacterial vaginosis status, resulting in a similar representation of black and white women in each of the 3 Nugent score categories (normal [0-3], intermediate [4-6], and bacterial vaginosis [7-10]). Sequencing of the 16S ribosomal gene (V4 region) was used to determine the dominant Lactobacillus species present (primarily Lactobacillus iners and Lactobacillus crispatus), defined as >50% of the community. Subjects without dominance by a single Lactobacillus species were classified as Diverse. A Candida-specific quantitative polymerase chain reaction targeting the internally transcribed spacer 1 was validated using vaginal samples collected from a second cohort of women and used to assess Candida colonization. Two hundred fifty-five nonpregnant women with sufficient bacterial biomass for analysis were included in the final analysis. Generalized linear models were used to evaluate associations between Lactobacillus dominance, sociodemographic and risk characteristics, and vaginal Candida colonization. In separate invitro studies, the potential of cell-free supernatants from Lactobacillus crispatus and Lactobacillus iners cultures to inhibit Candida growth was evaluated. Forty-two women (16%) were vaginally colonized with Candida. Microbiomes characterized as Diverse (38%), Lactobacillus iners-dominant (39%), and Lactobacillus crispatus-dominant (20%) were the most common. The microbiome, race, and Candida colonization co-varied with a higher prevalence of Candida among black women and Lactobacillus iners-dominant communities compared with white womenand Lactobacillus crispatus-dominant communities. Lactobacillus iners-dominant communities were more likely to harbor Candida than Lactobacillus crispatus-dominant communities (odds ratio, 2.85, 95%confidence interval, 1.03-7.21; Fisher exact test, P= .048). Invitro,Lactobacillus crispatus produced greater concentrations of lactic acid and exhibited significantly more pH-dependent growth inhibition of Candida albicans, suggesting a potential mechanism for the clinical observations. In nonpregnant women, Lactobacillus iners-dominant communities were significantly more likely to harbor Candida than Lactobacillus crispatus-dominant communities, suggesting that Lactobacillus species have different relationships with Candida. Invitro experiments indicate that Lactobacillus crispatus may impede Candida colonization more effectively than Lactobacillus iners through a greater production of lactic acid.

Potential of cell-free supernatants from cultures of selected lactic acid bacteria and yeast obtained from local fermented foods as inhibitors of Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus.

BackgroundFood-borne infections cause huge economic and human life losses worldwide. The most common contaminants of foods include Listeria monocytogenes Salmonellae and Staphylococcus aureus. L. monocytogenes is most notorious due to its tolerance to common food preservation methods and the risks it poses, including higher fatality rates. Safer, more efficacious control methods are thus needed. Along with food-borne pathogens, lactic acid bacteria (LAB) can also be found in foods. Some LAB isolates inhibit pathogenic bacteria by various mechanisms, including by production of antimicrobial metabolites.MethodsThe potential of cell-free culture supernatants (CFS) derived from broth cultures of selected local LAB and yeast isolates, some of which were subjected to various treatments, were tested for inhibition of L. monocytogenes, Salmonella spp. and S. aureus in in vitro culture by incorporating various proportions of the CFSs into the growth medium concurrently with inoculation (co-cultures) or following limited proliferation after inoculation of the pathogens (delayed cultures). The effects of the CFSs on various growth parameters were assessed.ResultsCFS from the LAB isolates were strongly inhibitory when co-cultured. The inhibitory activities were stable following heat or protease treatment of the CFSs. Inhibitory activity was dependent primarily on active substance(s) secreted into the supernatant. In all co-cultures, CFS proportion-dependent progressive decrease in the number of colonies was observed and both growth rates and number of generations were reduced with significantly fewer numbers of colony forming units, whereas generation times were significantly increased compared to those of controls. Transfer from co-cultures to fresh broth showed inhibited cultures contained bacteria that can re-grow, indicating the presence of viable bacteria that are undetectable by culture. Growth rates in CFS-treated delayed cultures were also reduced to varying degrees with the number of colonies in some cultures being significantly less than the corresponding control values. CFSs were active against both Gram-positive and –negative bacteria.ConclusionsActive metabolites produced and secreted by LAB into the growth medium were effective in inhibiting the tested pathogens. Early addition of the CFSs was necessary for significant inhibition to occur. Further studies will help make these findings applicable to food safety.