The COVID-19 is an acute and contagious disease characterized by pneumonia and ARDS. The disease is caused by SARS-CoV-2, which belongs to the family of Coronaviridae along with MERS-CoV and SARS-CoV-1. The virus has the positive-sense RNA as its genome encoding for ∼26 proteins that work together for the virus survival, replication, and spread in the host. The virus gets transmitted through the contact of aerosol droplets from infected persons. The pathogenesis of COVID-19 is highly complex and involves suppression of host antiviral and innate immune response, induction of oxidative stress followed by hyper inflammation described as the "cytokine storm," causing the acute lung injury, tissue fibrosis, and pneumonia. Currently, several vaccines and drugs are being evaluated for their efficacy, safety, and for determination of doses for COVID-19 and this requires considerable time for their validation. Therefore, exploring the repurposing of natural compounds may provide alternatives against COVID-19. Several nutraceuticals have a proven ability of immune-boosting, antiviral, antioxidant, anti-inflammatory effects. These include Zn, vitamin D, vitamin C, curcumin, cinnamaldehyde, probiotics, selenium, lactoferrin, quercetin, etc. Grouping some of these phytonutrients in the right combination in the form of a food supplement may help to boost the immune system, prevent virus spread, preclude the disease progression to severe stage, and further suppress the hyper inflammation providing both prophylactic and therapeutic support against COVID-19.

Interspecies transmissions of viruses between animals and humans may result in unpredictable pathogenic potential and new transmissible diseases. This mechanism has recently been exemplified by the discovery of new pathogenic viruses, such as the novel severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) pandemic, Middle-East respiratory syndromecoronavirus epidemic in Saudi Arabia, and the deadly outbreak of Ebola in West Africa. The. SARS-CoV-2 causes coronavirus disease-19 (COVID-19), which is having a massive global impact in terms of economic disruption, and, above all, human health. The disease is characterized by dry cough, fever, fatigue, myalgia, and dyspnea. Other symptoms include headache, sore throat, rhinorrhea, and gastrointestinal disorders. Pneumonia appears to be the most common and severe manifestation of the infection. Currently, there is no vaccine or specific drug for COVID-19. Further, the development of new antiviral requires a considerable length of time and effort for drug design and validation. Therefore, repurposing the use of natural compounds can provide alternatives and can support therapy against COVID-19. In this review, we comprehensively discuss the prophylactic and supportive therapeutic role of probiotics for the management of COVID-19. In addition, the unique role of probiotics to modulate the gut microbe and assert gut homeostasis and production of interferon as an antiviral mechanism is described. Further, the regulatory role of probiotics on gut-lung axis and mucosal immune system for the potential antiviral mechanisms is reviewed and discussed. Key points • Gut microbiota role in antiviral diseases • Factors influencing the antiviral mechanism • Probiotics and Covid-19

A bacterial strain that produces amylase and polyhydroxyalkanoate (PHA) was isolated, identified, and classified under the Bacillus cereus group based on 16S rRNA gene sequences and specific reaction in poly-myxin egg yolk Mannitol bromothymol blue agar (PEMBA) medium and in combination with microbiological and biochemical tests. The complete ORF of phaC gene was cloned by PCR technique and nucleotide sequences were determined. Results indicated that the phaC gene had 99% homology with phaC of B. cereus (AE016877.1), 98% with B. thuringiensis (AY331151.1), and 94% with several strains of B. anthracis and B. cereus group including Bacillus sp. INT005. However, only 90% sequence homology with phaC of B. megaterium (AF109909.2) was observed. The PHA production using different fermentable sugars was tested and it was found that the CFR06 was able to accumulate 36-60% of PHA in cell dry weight (CDW). Zymogram of amylase indicated that native strain produces an extracellular enzyme of *80 kDa. The potency of the organism to hydrolyze starch due to the intrinsic amylase activity was considered, and starch was used as the sole carbon source for growth and PHA production. GC, FTIR, and 1 H NMR analysis of the polymer indicated that the strain was a potent polyhydroxybutyrate (PHB) producer. The bacterium accumulated about 48% PHA in CDW in a starch containing medium.

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