Smear-ripened cheeses host complex microbial communities that play a crucial role in the ripening process. Although bacteriophages have been frequently isolated from dairy products, their diversity and ecological role in such type of cheese remain underexplored. In order to fill this gap, the main objective of this study was to isolate and characterize bacteriophages from the rind of a smear-ripened cheese. Thus, viral particles extracted from cheese rind were tested against a collection of bacterial isolates through a spot assay. In total, five virulent bacteriophages infecting Brevibacterium aurantiacum, Glutamicibacter arilaitensis, Leuconostoc falkenbergense and Psychrobacter aquimaris species were obtained. All exhibit a narrow host range, being only able to infect a few cheese-rind isolates within the same species. The complete genome of each phage was sequenced using both Nanopore and Illumina technologies, assembled and annotated. Sequence comparison with known phages revealed that four of them may represent at least new genera. The distribution of the five virulent phages into the dairy-plant environment was also investigated by PCR and three potential reservoirs were identified. This work provides new knowledge on the cheese rind viral community and an overview of the distribution of phages within a cheese factory.

Leptospirosis remains an important worldwide zoonotic disease caused by Leptospira spp affecting human and animals. This research aims to study the virulent-associated secreted proteins (protein secretome) of pathogenic Leptospira interrogans serovar Icterohemorrhagiae strain RGA (Leptospira RGA) transition from the environment to mammalian physiological osmolarity, temperature (37 °C) and carbon dioxide concentration (5% CO2) conditions for 24 h. Mass Spectrometry and bioinformatics approaches, we identified 69 potential secreted proteins from the culture supernatant of the Leptospira RGA isolate. We discovered transporters and porins such as phosphate porin, outer membrane efflux, ompA family protein, and polymer-forming cytoskeletal family protein under hyperosmotic condition. Under heat stress, degradation enzymes included zinc metallopeptidase, M23 family (LA3456, LA0709), Rhs family protein (LA1765), thermolysin metallopeptidase; / hydrolase family (LA1345, LA2501). Oxidative stress response proteins induced by osmolarity and temperature shifts included chaperon GrpE, DnaK (LA3705), antioxidants, i.e., thiol-specific redoxin, and peroxiredoxin (LA2809). In response to the in vivo transition, metabolic and other enzymes involved in energy production (COG:C), amino acid metabolism and transport (COG:E), and lipid metabolism and transport (COG:I), as well as moonlighting proteins functionally binding to plasminogen and fibronectin and regulating transcription, were also discovered. An overview of secreted proteins will supplement our understanding of Leptospira biology and pathogenesis during infection and also in response to environmental stimuli and their potential virulent determinants have the potential for developing leptospirosis vaccines and diagnosis.

Escherichia coli causes several infections like intestinal diarrhea, urinary tract infections, and pneumonia, which are difficult to treat due to the emergence of antimicrobial resistance. The World Health Organisation (WHO) declared carbapenem-resistant E. coli a critical pathogen and called for the development of new antimicrobial agents. Phage therapy, a century-old technique, has been revitalised recently with many successful applications against multi-drug resistant infections. As such, phage therapy is considered one of the most effective alternatives or adjuvants to antibiotics and is also effective in treating multidrug-resistant (MDR) bacterial infections. However, few phages that can kill pathogenic E. coli strains from Southeast Asia have been studied at a molecular level, although the burden of MDR, particularly carbapenem resistance, is high in this region. In this study, three closely related obligately virulent Escherichia phages (øEc_Makalu_001, øEc_Makalu_002, and øEc_Makalu_003) that could infect uropathogenic E. coli were isolated from sewage samples and characterized using morphological as well as sequence-based analysis. Further, a comparative genomic and phylogenetic analysis was done to predict the functional genes and evolutionary relationships. Electron microscopy and genome-based classification revealed that all three phages belonged Krischvirus genus of Straboviridae family. One-step growth curve showed that the latent period of the phages ranged from 15-20 min, the outbreak period was about 50 min, and the burst size ranged between 74-127 PFU/bacterium. Moreover, the phages could tolerate a pH range of 6 to 9 and a temperature range of 25-37°C for up to 180 minutes without significant loss of phage viability. Spotting the purified phages in different clinical isolates showed a broad host-range of isolated Escherichia phages and could lyse up to 30% of the tested pathogenic clinical isolates, including an intra-genus isolate of Klebsiella pneumoniae. The genome organization of all three phages was almost identical and similar to T4-like phage with a full-length genome of ~163 kb. Around 284 coding sequences (CDS) were predicted in each phage, of which only 40% were functional with an average gene length of 951 bp. The coding density in all phages was approximately 95%, while the gene density was 1.73 gene/kbp. Putative lysin, holin, endolysin, and spanin genes were found in the genomes of all three phages, resembling that of T4-like phages implying their phylogenetic relatedness. Furthermore, various in silico sequence analysis tools confirmed that all three phages were strictly virulent with functional lysis modules but devoid of any known virulence or toxin genes, integron-associated genes and antimicrobial-resistance (AMR) genes. In summary, pre-clinical experimental analysis and exploration of genomic features suggest that all three phages may be suitable candidates for therapeutic applications against uropathogenic E. coli.