Noureddine Bouras

A novel halophilic actinobacterium, designated H202 ^T , was isolated from a Saharan soil in the Ahbès region (Béni-Isguen, Ghardaïa province, South Algeria), and its taxonomic position was determined by a genome-based polyphasic approach. Phylogenetic analysis of the 16S rRNA gene sequence revealed that the strain H202 ^T belonged to the genus Actinopolyspora and showed the highest sequence similarity to Actinopolyspora mzabensis DSM 45460 ^T (99.46%). Comparative genomic analysis based on digital DNA–DNA hybridization (dDDH), average nucleotide identity (ANI) and average amino acid identity (AAI) showed values below the recommended species cut-off thresholds of 70% (dDDH) and 95–96% (ANI and AAI), suggesting that the strain H202 ^T represents a novel species. This strain exhibits the typical characteristics of the genus Actinopolyspora . The cell-wall hydrolysates contained meso -diaminopimelic acid, and the diagnostic whole-cell sugars were arabinose and galactose. Phosphatidylcholine was identified as the diagnostic phospholipid, and the predominant menaquinones were MK-9(H ₄ ) and MK-10(H ₄ ). The major fatty acids (≥10%) were anteiso -C _17:0 , iso -C _15:0 , iso -C _16:0 and anteiso -C _15:0 . The genome size of strain H202 ^T was estimated to be 5.2 Mbp, with a G+C content of 67.5%. Based on these findings, strain H202 ^T is proposed as a representative of a novel species within the genus Actinopolyspora , named Actinopolyspora sabaoui sp. nov. The type strain is H202 ^T (=DSM 46671 ^T =CECT 31287 ^T ).

Due to their technological and functional properties, lactic acid bacteria (LAB) contribute to improving the nutritional value and extending the shelf life of food products. However, the heterogeneity, biodiversity, and complex metabolic pathways of LAB species have required significant scientific efforts to isolate, characterize, and optimize their applications in food technology. Furthermore, variations in prevalence and composition across regions and countries pose additional challenges, driven by the intrinsic capacity of these bacteria to evolve into mutant strains in response to environmental conditions. Within this intricate framework, this study provides an in‐depth overview of LAB prevalence and biodiversity in Maghrebian countries, highlighting recent findings on their metabolic pathways. In addition, the molecular and physiological features of newly isolated LAB species originating from the Maghreb are assessed. This review is of particular significance as it provides an updated and region‐focused synthesis of recent biotechnological advances in LAB in Maghrebian countries. It highlights their broader implications for sustainable food systems, functional food innovation, and the valorization of local microbial resources.

An in silico genomic analysis was performed on Stenotrophomonas sp. strain 1800 to clarify its taxonomic position and functional potential. The 16S rRNA gene sequence showed 100% similarity to S. geniculata ATCC 19374T, and both strains shared identical genome size (4.8 Mb) and G+C content (66.2%). Genome-based comparisons revealed low relatedness between strain 1800 and S. maltophilia NBRC 14161ᵀ (dDDH 47.8%, ANI 92.4%), whereas high dDDH (86.9%) and ANI (98.5%) values with S. geniculata ATCC 19374T unambiguously support the reclassification of strain 1800 as S. geniculata. Functional annotation showed that core metabolic pathways dominate the genome, with 1568 genes assigned to subsystems, mainly involved in amino acid and protein metabolism. The CAZome represents 1.81% of predicted coding sequences, indicating notable carbohydrate-transforming capacity. Additionally, the genome encodes diverse virulence-, persistence-, and antimicrobial resistance-associated determinants, as well as genes involved in xenobiotic degradation and heavy metal resistance, suggesting both the clinical relevance and bioremediation potential of this strain.

Actinobacteria from extreme environments represent a valuable source of novel bioactive secondary metabolites with potential antimicrobial applications. The aim of this study was to isolate, identify, and evaluate the antimicrobial potential of a newly isolated strain of actinobacteria. AHA8 strain, was isolated from an Algerian desert soil sample in the Ahaggar region (Tamanrasset) by the dilution-agar plating method using a chitin-vitamins B medium supplemented with nalidixic acid and actidione. Morphological characterization indicated that this strain belonged to the genus Streptomyces. Phylogenetic analysis based on the 16S rRNA gene showed that the strain is closely related to Streptomyces djakartensis NBRC 15409T (99.57% sequence similarity). Strain AHA8 showed very strong activity against pathogenic staphylococci, including Staphylococcus aureus (MRSA 639c), as well as against other Gram-positive bacteria: Bacillus subtilis (ATCC 663) and Listeria monocytogenes (ATCC 13932). Additionally, the strain exhibited a moderate activity against mycotoxigenic and phytopathogenic fungi, including Aspergillus carbonarius (M333), A. westerdijkiae (ATCC 3174), Fusarium culmorum (Fc), and Umbelopsis ramanniana (NRRL 1829). Almost the same results were observed for Gram-negative bacteria and the pathogenic yeast Candida albicans (M3). Therefore, four solvents (n-hexane, dichloromethane, ethyl acetate, and n-butanol) were used to extract the bioactive secondary metabolites produced by the AHA8 culture on a synthetic starch medium. The highest antibacterial activity was obtained with the butanolic and ethyl acetate extracts. These findings demonstrate that the desert-derived strain AHA8 represents a promising source of antimicrobial secondary metabolites and supports further studies aimed at the purification and characterization of its bioactive compounds.

The Fragrant plants hold significant value in various fields, including health, food, pharmacy, cosmetics, and phytopharmacy. The objective of this study is to examine the diversity and importance of fragrant plants in the hydrographic network of the Mzab region (Northern Algerian Sahara). For this purpose, following a subjective sampling method, we conducted 20 phytoecological surveys in four representative sites. To study diversity, we used ecological indices, functional traits and chorology. The results revealed the presence of 28 species belonging to 26 genera and 20 botanical families, with the most important being Apiaceae, Poaceae and Brassicaceae, accounting for 32.46%, 20.52% and 20.05%, respectively. Morphological and biological spectra showed the dominance of perennial species (81.44%) and chamaephytes (60.82%). The chorological spectrum revealed the dominance of Mediterranean-Saharo-Arabian species, followed by Saharo-Arabian elements, with 51.31% and 28.30%, respectively. Fragrant plants (56.25%) overwhelmingly dominate the studied vegetation cover compared to non-fragrant plants (43.75%). These multi-use plants constitute a raw material for the development of a bio-industry in arid zones, based on the use of bioresources and environmental conservation.

Wheat (Triticum aestivum L.), a staple crop in Algeria and other semi-arid regions, faces significant challenges from fungal pathogens like Fusarium culmorum, which cause substantial yield losses and threaten food security. This study investigates the biocontrol and plant growth-promoting potential of Streptomyces sp. D15, an actinobacterial strain isolated from steppe soil in Algeria. Phylogenomic analysis confirmed the classification of strain D15 as Streptomyces lavendofoliae. During in planta experiments on wheat seedlings, strain D15 improved shoot length with increases of 67% relative to control and 120% relative to FC-infested seedlings. Results revealed the strain's ability to significantly reduce the severity of F. culmorum-induced seedling blight, achieving 91% reduction in disease incidence and 87% reduction in disease severity. Additionally, D15 enhanced wheat emergence rate (143% improvement) and increased root lateral branching by 391% compared to infested seedlings. Genome annotation identified a diverse range of genes linked to biocontrol mechanisms, including chitinolytic enzymes, siderophore production, and antifungal secondary metabolites such as hydrogen cyanide. Moreover, genes related to phosphate solubilization and phytohormone biosynthesis, including indole-3-acetic acid and gibberellic acid, were detected, explaining the observed plant growth-promoting effects. This comprehensive investigation highlights Streptomyces sp. D15 as a promising biocontrol agent and growth promoter, offering an eco-friendly and sustainable alternative to chemical pesticides. Its remarkable adaptability to semi-arid environments and its potential for agricultural applications position it as a valuable tool for enhancing wheat productivity and resilience in regions facing both biotic and abiotic stressors.

The genus Clostridium encompasses phylogenetically diverse, obligately anaerobic, Gram-positive, spore-forming bacteria, yet taxonomic resolution for several members remains limited by the conservatism of the 16S rRNA gene. We reassessed four closely related species pairs: Clostridium baratii and Clostridium nitritogenes ; Clostridium thermopalmarium and Clostridium colicanis ; Clostridium botulinum and Clostridium combesii ; and Clostridium estertheticum subsp. estertheticum and Clostridium estertheticum subsp. laramiense . A polyphasic framework was applied, integrating 16S rRNA and core-genome phylogenies, whole-genome relatedness metrics (digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity), phenotypic characterization and carbohydrate-active enzyme profiling. Concordant genomic and phenotypic evidence supported the synonymization of C. nitritogenes (Prévot 1940) Bernard et al . 2018 with C. baratii (Prévot 1938) Holdeman and Moore 1970, C. colicanis Greetham et al . 2003 with C. thermopalmarium Soh et al . 1991 and C. estertheticum subsp. laramiense (Kalchayanand et al . 1993) Spring et al . 2003 with C. estertheticum subsp. estertheticum (Collins et al . 1993) Spring et al . 2003. By contrast, despite high genomic relatedness, C. botulinum (van Ermengem 1896) Bergey et al . 1923 and C. combesii (Prévot and Laplanche 1947) Bernard et al . 2018 displayed reproducible phenotypic and functional distinctions consistent with subspecies status. We, therefore, propose C. botulinum subsp. combesii comb. nov., alongside C. botulinum subsp. botulinum comb. nov., thereby refining genome-based classification within the genus.