Phenotypic Characterization and Genotypic Subtyping of Salmonella enterica Serovars Enteritidis and Gallinarum Isolated from Human and Poultry-Related Samples

Genomic Insights and Antimicrobial Potential of Newly Streptomyces cavourensis Isolated from a Ramsar Wetland Ecosystem

The growing threat of antimicrobial resistance underscores the urgent need to identify new bioactive compounds. In this study, a Streptomyces strain, ACT158, was isolated from a Ramsar wetland ecosystem and found to exhibit broad-spectrum effects against Gram-positive and Gram-negative bacteria, as well as fungal pathogens. The active strain was characterized as S. cavourensis according to its morphology, phylogenetic analysis, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH). Whole-genome sequencing (WGS) and annotation revealed a genome size of 6.86 Mb with 5122 coding sequences linked to carbohydrate metabolism, secondary metabolite biosynthesis, and stress responses. Genome mining through antiSMASH revealed 32 biosynthetic gene clusters (BGCs), including those encoding polyketides, nonribosomal peptides, and terpenes, many of which showed low similarity to known clusters. Comparative genomic analysis, showing high genomic synteny with closely related strains. Unique genomic features of ACT158 included additional BGCs and distinct genes associated with biosynthesis pathways and stress adaptation. These findings highlight the strain's potential as a rich source of bioactive compounds and provide insights into its genomic basis for antimicrobial production and its ecological and biotechnological significance.

Unraveling the enzymatic and antibacterial potential of rare halophilic actinomycetes from Algerian hypersaline wetland ecosystems

The study aimed to isolate rare halophilic actinomycetes from hypersaline soils of Algerian inland Wetland Ecosystems "Sebkhas-Chotts" located in arid and hot hyperarid lands with international importance under the Ramsar Convention and to explore their enzyme-producing and antibacterial abilities. The halophilic actinomycetes were selectively isolated using agar-rich media supplemented with 5, 10, and 15% (W/V) of total salts. Thirty-one isolates were obtained and 16S rRNA gene sequencing analysis revealed the presence of members affiliated to rare halophilic actinobacterial genera (Actinopolyspora and Nocardiopsis) accounting for 74.19% (23 isolates out of 31) and 25.8% (8 isolates), respectively. Both phylotypes are alkalitolerant and halophilic thermotolerant actinomycetes displaying significant hydrolytic activities relative to (amylase, asparaginase, cellulase, esterase, glutaminase, inulinase, protease, pectinase, xylanase), and over 96% of tested isolates exhibited all common enzymes, mainly active at 10% of growing salt. In addition, high antibacterial activity was observed against Bacillus cereus, Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus. The findings showed that saline wetlands ecosystems represent a rich reservoir for the isolation of significant rare halophilic actinomycetes with potential adaptive features and valuable sources for novel bioactive metabolites and biocatalysts of biotechnological interest.

Rapid screening and characterization of bacteria associated with hospital cockroaches (Blattella germanica L.) using MALDI-TOF mass spectrometry

AIMS

The study aimed to explore the diversity of culturable microbiota colonizing the alimentary tract and outer surfaces of German cockroaches (Blattella germanica) captured in a health care facility.

METHODS AND RESULTS

Microbial identification was conducted using Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) Biotyper and 16S rRNA sequencing. A total of 181 bacteria strains were isolated from 25 cockroach specimens and the MALDI-TOF MS-based assay yielded direct identification of 96·5% (175 out of 181) of the strains at the species level. The proteomic fingerprinting mainly revealed strains belonged to Gram-negative Enterobacteria (103) with six different genera that were characterized including Citrobacter, Klebsiella, Kluyevera, Leclercia, Morganella and Serratia. In addition, Pseudomonas sp. strains ranked in second with 29·8% (54 strains) followed by Staphylococcus sp. (6·62%) and Enterococcus sp. (1·65%). A large number of these bacteria (n = 90, 49·72%) was found in cockroaches captured in the maternity ward, whereas 45 strains (24·8%) were recovered in the paediatric ward. Altogether, 24 bacterial species were identified from both the external surface and digestive tract of the insect, of which Serratia marcescens presented the major group (n = 80, 44·19%) followed by Pseudomonas aeruginosa (n = 53, 29·28%) and Klebsiella oxytoca (n = 9, 4·94%).

CONCLUSION

The findings showed a high prevalence of bacterial pathogens harboured in the body and alimentary tract of B. germanica captured in a health care facility.

SIGNIFICANCE AND IMPACT OF THE STUDY

This investigation shows the possible role of German cockroaches as a source for bacterial pathogens, increasing the likelihood of direct transmission of healthcare associated infections, and thereby representing a public health risk. In addition, the present study revealed a high discriminatory power of the mass spectra investigation and a competent bacterial typing tool that extends phenotypic and genotypic approaches, which allows new possibilities for fast and accurate diagnosis in medical entomology.