Actinobacteria Derived from Algerian Ecosystems as a Prominent Source of Antimicrobial Molecules

Abstract

Actinobacteria, in particular "rare actinobacteria" isolated from extreme ecosystems, remain the most inexhaustible source of novel antimicrobials, offering a chance to discover new bioactive metabolites. This is the first overview on actinobacteria isolated in Algeria since 2002 to date with the aim to present their potential in producing bioactive secondary metabolites. Twenty-nine new species and one novel genus have been isolated, mainly from the Saharan soil and palm groves, where 37.93% of the most abundant genera belong to Saccharothrix and Actinopolyspora. Several of these strains were found to produce antibiotics and antifungal metabolites, including 17 new molecules among the 50 structures reported, and some of these antibacterial metabolites have shown interesting antitumor activities. A series of approaches used to enhance the production of bioactive compounds is also presented as the manipulation of culture media by both classical methods and modeling designs through statistical strategies and the associations with diverse organisms and strains. Focusing on the Algerian natural sources of antimicrobial metabolites, this work is a representative example of the potential of a closely combined study on biology and chemistry of natural products.

Keywords: Saharan ecosystem.; actinobacteria; antibiotic; antifungal; antimicrobial; chemodiversity; rare actinobacteria; secondary metabolites.

Figure 1

Distribution of the most explored Actinobacteria sampling sites in Algeria. 1: Algiers, 2: Tizi Ouzou, 3: Bejaia, 4: Jijel, 5: Annaba, 6: El Taref, 7: Constantine, 8: Djelfa, 9: Biskra, 10: Khenchela, 11: Laghouat, 12: El Oued, 13: Ouargla, 14: Ghardaia, 15: Bechar, 16: Adrar, and 17: Tamarasset. Details are in Table 1.

Figure 2

Variation in the number of publications dealing with the isolation and metabolic profile investigation of actinobacteria in Algeria based on data since 2002 to the present.

Figure 3

Variation in number of culturable novel actinobacteria species collected from Algerian sources since 2002.

Figure 4

Proportion of novel species, genera, and rare actinobacteria strains from different Algerian ecosystems reported since 2002 (a), according to the places of collection (b). Details are in Figure 1.

Figure 5

Venn diagram showing the numbers of shared and unique rare actinobacterial genera among the three most dominant Saharan soil samples sites.

Figure 6

Molecular structures of the bioactive metabolites 1–31 isolated from Algerian actinobacteria: The stereochemical details are according the cited references.

Figure 7

Molecular structures of the bioactive metabolites 32–50 isolated from Algerian actinobacteria. The stereochemical details are according the cited references.