Microorganisms

COVID-19 can cause long-term symptoms, such as a post-infection syndrome, known as Long-COVID. Among the symptoms present during this period, the most reported are gastrointestinal symptoms. This study discusses the effects of changes in the gut microbiota of post-COVID-19 patients. SARS-CoV-2 infection is associated with significant alterations in gut microbial composition, disturbing its homeostasis and promoting a reduction in the abundance of beneficial symbiotic bacteria and an increase in the abundance of opportunistic pathogens. Furthermore, the composition of the gut microbiota may play a role in the prognosis of patients with post-COVID-19 infection. The microbiota of the intestinal tract and the respiratory tract influence each other; therefore, the gut–lung axis has attracted increasing interest in understanding COVID-19. Moreover, the brain–gut axis has been studied, since there have been reports of anxiety and depression along with post-COVID-19 gastrointestinal symptoms. Treatments options for intestinal dysbiosis in Long-COVID patients include probiotics, prebiotics, and fecal microbiota transplantation. These treatments may serve as an approach to improve gastrointestinal symptoms during Long-COVID, increasing microbiome diversity, strengthening the integrity of intestinal barrier functions, and consequently influencing the treatment of COVID-19.

Terpenes are the largest category of specialised metabolites. Aerobic endospore-forming bacteria (AEFB), a diverse group of microorganisms, can thrive in various habitats and produce specialised metabolites, including terpenes. This study investigates the potential for terpene biosynthesis in 10 AEFB strain whole-genome sequences by performing a bioinformatics analyses to identify genes associated with these isoprene biosynthesis pathways. Specifically, we focused on the sequences coding for enzymes in the methylerythritol-phosphate (MEP) pathway and the polyprenyl synthase family, which play crucial roles in synthesising terpene precursors together with terpene synthases. A comparative analysis revealed the unique genetic architecture of these biosynthetic gene clusters (BGCs). Our results indicated that some strains possessed the complete genetic machinery required to produce terpenes such as squalene, hopanoids, and carotenoids. We also reconstructed phylogenetic trees based on the amino acid sequences of terpene synthases, which aligned with the phylogenetic relationships inferred from the whole-genome sequences, suggesting that the production of terpenes is an ancestor property in AEFB. Our findings highlight the importance of genome mining as a powerful tool for discovering new biological activities. Furthermore, this research lays the groundwork for future investigations to enhance our understanding of terpene biosynthesis in AEFB and the potential applications of these Brazilian environmental strains.

Cryptosporidium is a waterborne gastrointestinal parasite that causes diarrheal disease worldwide. Currently, there are no effective therapeutics to treat cryptosporidiosis. Since natural products are a known source of anti-parasitic compounds, we screened a library of extracts and pure compounds isolated from bacteria and fungi collected from subterranean environments for anti-Cryptosporidium activity. Seven norditerpene lactones isolated from the fungus Oidiodendron truncatum collected from the Soudan Iron mine in Minnesota showed potent activity and were further tested to identify the most active compounds. The availability of a diverse suite of natural structural analogs with varying activities allowed us to determine some structure–activity relationships for both anti-parasitic activity and cytotoxicity. The two most potent compounds, oidiolactones A and B, had EC₅₀s against C. parvum of 530 and 240 nM, respectively, without cytotoxicity to host cells. Both compounds also inhibited the related parasite Toxoplasma gondii. Oidiolactone A was active against asexual, but not sexual, stages of C. parvum, and killed parasites within 8 h of treatment. This compound reduced C. parvum infection by 70% in IFNγ−/− mice, with no signs of toxicity. The high potency, low cytotoxicity, and in vivo activity combined with high production and synthetic accessibility make these oidiolactones attractive scaffolds for the development of new anti-Cryptosporidium therapeutics.