Antimycotic effect of 3-phenyllactic acid produced by probiotic bacterial isolates against Covid-19 associated mucormycosis causing fungi.

The Covid-19 associated mucormycosis (CAM) is an emerging disease affecting immunocompromised patients. Prevention of such infections using probiotics and their metabolites persist as effective therapeutic agents. Therefore, the present study emphasizes on assessment of their efficacy and safety. Samples from different sources like human milk, honey bee intestine, toddy, and dairy milk were collected, screened and characterized for potential probiotic lactic acid bacteria (LAB) and their metabolites to be used as effective antimicrobial agents to curtail CAM. Three isolates were selected based on probiotic properties and characterized as Lactobacillus pentosus BMOBR013, Lactobacillus pentosus BMOBR061 and Pediococcus acidilactici BMOBR041 by 16S rRNA sequencing and MALDI TOF-MS. The antimicrobial activity against standard bacterial pathogens showed ˃9 mm zone of inhibition. Furthermore, the antifungal activity of three isolates was tested against Aspergillus flavus MTCC 2788, Fusarium oxysporum, Candida albicans and Candida tropicalis where the results showed significant inhibition of each fungal strain. Further studies were carried out on lethal fungal pathogens like Rhizopus sp. and two Mucor sp. which are associated with post Covid-19 infection in immunosuppressed diabetic patients. Our studies on CAM inhibitory effect of LAB revealed the efficient inhibition against Rhizopus sp. and two Mucor sp. The cell free supernatants of three LAB showed varied inhibitory activity against these fungi. Following the antimicrobial activity, the antagonistic metabolite 3-Phenyllactic acid (PLA) in culture supernatant was quantified and characterized by HPLC and LC-MS using standard PLA (Sigma Aldrich). The isolate L. pentosus BMOBR013 produced highest PLA (0.441 g/L), followed by P. acidilactici BMOBR041 (0.294 g/L) and L. pentosus BMOBR061 (0.165 g/L). The minimum inhibitory concentration of HPLC eluted PLA on the Rhizopus sp. and two Mucor sp. was found to be 180 mg/ml which was further confirmed by inhibition of total mycelia under live cell imaging microscope.

Oral administration of Lactic acid bacteria inhibits PEDV infection in young piglets.

Since the emergence of the highly pathogenic porcine epidemic diarrhea virus (PEDV) strain in 2010, the prevention of porcine epidemic diarrhea (PED) in pig farms remains problematic. To find the reasons behind the high mortality in young piglets, the relative mRNA expression of inflammation-related factors in infected pigs of different ages as well as uninfected pigs were detected by RT-qPCR. The results showed that the mRNA expression of these factors including IL-6 and TNF-α was more increased in infected younger piglets than infected older pigs. To clarify the relationship between these inflammation related factors, the pairwise linear correlation between the relative expression of these factors were analyzed and showed as network mapping with different correlation coefficients. A strong positive correlation was observed between the expression of various factors in 1-week-old piglets. Combined with the difference in mortality of PEDV infection in pigs of different ages, we hypothesized that lactic acid bacteria (LAB) could inhibit PEDV infection in newborn piglets, and an in vivo experiment was carried out. The results of survival rate and wet/dry ratio showed that LAB alleviated PEDV indued mortality and diarrhea. The detection of viral copies and tissue section staining showed less observed viruses in LAB treated pig. RT-qPCR results of gene expression in intestines showed that LAB modulated the gene expression of various host barrier genes, indicating that LAB is potential to inhibit PEDV infection by regulating the host intestinal barrier. However, to use LAB as therapy, how to improve the efficiency on inhibiting PEDV infection needs further studies.

The Role of Mucosal Immunity and Recombinant Probiotics in SARS-CoV2 Vaccine Development.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), causing the 2019 novel coronavirus disease (COVID-19), was introduced by WHO (World Health Organization) as "pandemic" in March 2020. According to WHO, thus far (23 November 2020) 58,425,681 infected cases including 1,385,218 deaths have been reported worldwide. In order to reduce transmission and spread of this lethal virus, attempts are globally being made to develop an appropriate vaccine. Intending to neutralize pathogens at their initial entrance site, protective mucosal immunity is inevitably required. In SARS-CoV2 infection and transmission, respiratory mucosa plays a key role; hence, apparently mucosal vaccination could be a superior approach to elicit mucosal and systemic immune responses simultaneously. In this review, the advantages of mucosal vaccination to control COVID-19 infection, limitations, and outcomes of mucosal vaccines have been highlighted. Considering the gut microbiota dysregulation in COVID-19, we further provide evidences on utilization of recombinant probiotics, particularly lactic acid bacteria (LAB) as vaccine carrier. Their intrinsic immunomodulatory features, natural adjuvanticity, and feasible expression of relevant antigen in the mucosal surface make them more appealing as live cell factory. Among all available platforms, bioengineered probiotics are considered as the most affordable, most practical, and safest vaccination approach to halt this emerging virus.

Naturally occurring melatonin: Sources and possible ways of its biosynthesis.

According to recent reports, the global market for melatonin is worth 700 million USD in 2018 and would reach 2,790 million USD by 2025, growing at a CAGR of 18.9% during 2019 to 2025. Having regard to the prevalence of sleep and circadian rhythm disorders and a clear tendency to increase the demand for melatonin, and the current lack of alternative green and cost-efficient technologies of its synthesis, the supply of this remedy will not be enough to guarantee melatonin supply and affordability on a global scale. The emergence of naturally occurring melatonin and its isomers in fermented foods has opened an exciting new research area; there are still, however, some obscure points in the efficient microbiological biosynthesis of melatonin. This review summarizes the research progress and recent evidence related to melatonin and its isomers in various foodstuffs. Additionally, one possible way to synthesize melatonin is also discussed. The evidence pointed out that the presence of melatonin and its isomers is not exclusive for grapes and grape-derived products, because it can be also found in sweet and sour cherries. However, different species of both Saccharomyces and non-Saccharomyces yeasts could be used to obtain melatonin and melatonin isomers in the process of alcoholic fermentation biotechnologically. The availability of L-tryptophan has been a key factor in determining the concentration of indolic compounds produced, and the utilization of probiotic lactic acid bacteria could help in the formation of melatonin isomers during malolactic fermentation. These approaches are environmentally friendly alternatives with a safer profile than conventional ones and could represent the future for sustainable industrial-scale melatonin production.

Cabbage and fermented vegetables: From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19.

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT1 R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT1 R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.