In Silico Prediction of Secondary Metabolites and Biosynthetic Gene Clusters Analysis of <i>Streptomyces thinghirensis</i> HM3 Isolated from Arid Soil

Natural products produced by microorganisms are considered an important resource of bioactive secondary metabolites, such as anticancer, antifungal, antibiotic, and immunosuppressive molecules. Streptomyces are the richest source of bioactive natural products via possessing a wide number of secondary metabolite biosynthetic gene clusters (SM-BGCs). Based on rapid development in sequencing technologies with advances in genome mining, exploring the newly isolated Streptomyces species for possible new secondary metabolites is mandatory to find novel natural products. The isolated Streptomyces thinghirensis strain HM3 from arid and sandy texture soil in Qassim, SA, exerted inhibition activity against tested animal pathogenic Gram-positive bacteria and pathogenic fungal species. In this study, we report the draft genome of S. thinghirensis strain HM3, which consists of 7,139,324 base pairs (bp), with an average G+C content of 71.49%, predicting 7949 open reading frames, 12 rRNA operons (5S, 16S, 23S) and 60 tRNAs. An in silico analysis of strain HM3 genome by the antiSMASH and PRISM 4 online software for SM-BGCs predicted 16 clusters, including four terpene, one lantipeptide, one siderophore, two polyketide synthase (PKS), two non-ribosomal peptide synthetase (NRPS) cluster)/NRPS-like fragment, two RiPP/RiPP-like (ribosomally synthesised and post-translationally modified peptide product), two butyrolactone, one CDPS (tRNA-dependent cyclodipeptide synthases), and one other (cluster containing a secondary metabolite-related protein that does not fit into any other category) BGC. The presented BGCs inside the genome, along with antibacterial and antifungal activity, indicate that HM3 may represent an invaluable source for new secondary metabolites

Biodiesel Production by Single and Mixed Immobilized Lipases Using Waste Cooking Oil

Biodiesel is one of the important biofuels as an alternative to petroleum-based diesel fuels. In the current study, enzymatic transesterification reaction was carried out for the production of biodiesel from waste cooking oil (WCO) and experimental conditions were optimized, in order to reach maximum biodiesel yield. Bacillus stearothermophilus and Staphylococcus aureus lipase enzymes were individually immobilized on CaCO3 to be used as environmentally friendly catalysts for biodiesel production. The immobilized lipases exhibited better stability than free ones and were almost fully active after 60 days of storage at 4 &deg;C. A significant biodiesel yield of 97.66 &plusmn; 0.57% was achieved without any pre-treatment and at 1:6 oil/methanol molar ratio, 1% of the enzyme mixture (a 1:1 ratio mixture of both lipase), 1% water content, after 24 h at 55 &deg;C reaction temperature. The biocatalysts retained 93% of their initial activities after six cycles. The fuel and chemical properties such as the cloud point, viscosity at 40 &deg;C and density at 15 &deg;C of the produced biodiesel complied with international specifications (EN 14214) and, therefore, were comparable to those of other diesels/biodiesels. Interestingly, the resulting biodiesel revealed a linolenic methyl ester content of 0.55 &plusmn; 0.02% and an ester content of 97.7 &plusmn; 0.21% which is in good agreement with EN14214 requirements. Overall, using mixed CaCO3-immobilized lipases to obtain an environmentally friendly biodiesel from WCO is a promising and effective alternative for biodiesel production catalysis

First Report of IMI-2-Producing <i>Enterobacter bugandensis</i> and CTX-M-55-Producing <i>Escherichia coli</i> isolated from Healthy Volunteers in Tunisia

The aim of this study was to characterize the prevalence of fecal carriage of extended-spectrum beta-lactamases and carbapenemase-producing Gram-negative bacteria among healthy humans in Tunisia. Fifty-one rectal swabs of healthy volunteers were plated on MacConkey agar plates supplemented with cefotaxime or imipenem. The occurrences of resistance genes, integrons, and phylogroup typing were investigated using PCR and sequencing. The genetic relatedness of isolates was determined by pulsed-field-gel-electrophoresis (PFGE) and multilocus-sequence-typing (MLST). Whole-genome-sequencing (WGS) was performed for the carbapenem-resistant isolate. Sixteen ESBL-producing Escherichia coli isolates and one carbapenem-resistant Enterobacter bugandensis were detected out of the fifty-one fecal samples. The ESBL-producing E. coli strains contained genes encoding CTX-M-15 (n = 9), CTX-M-1 (n = 3), CTX-M-27 (n = 3), and CTX-M-55 (n = 1). Three CTX-M-1-producers were of lineages ST131, ST7366, and ST1158; two CTX-M-15-producers belonged to lineage ST925 and ST5100; one CTX-M-27-producer belonged to ST2887, and one CTX-M-15-producer belonged to ST744. Six isolates contained class 1 integrons with the following four gene cassette arrangements: dfrA5 (two isolates), dfrA12-orf-aadA2 (two isolates), dfrA17-aadA5 (one isolate), and aadA1 (one isolate). E. bugandensis belonged to ST1095, produced IMI-2 carbapenemase, and contained qnrE1 and fosA genes. A genome-sequence analysis of the E. bugandensis strain revealed new mutations in the blaACT and qnr genes. Our results reveal an alarming rate of ESBL-E. coli in healthy humans in Tunisia and the first description of IMI-2 in E. bugandensis.</i