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.

Identification of antagonistic Streptomyces strains isolated from Algerian Saharan soils and their plant growth promoting properties

“…Algerian Sahara is characterized by a hot arid climate and presents a particular ecosystem. Recently, there has been a new interest in the resources of actinobacteria from Algerian arid zones, considering that high temperatures can induce metabolic adaptations which could result in the production of interesting metabolites (Djinni et al 2019). Effectively, many studies have contributed to the finding of new species of actinobacteria in poorly explored arid environments, notably through the isolation of rare genera: Mzabimyces algeriensis (Saker et al 2014), Actinopolyspora algeriensis (Meklat et al 2012), Planomonospora algeriensis (Chaabane-Chaouch et al 2017).…”

“…As a result, from 2002 to 2019, one new genus and twenty-nine new species were obtained, mainly from palm groves and Algerian Saharan soils. Several of these strains were proved capable of producing antibacterial and antifungal metabolites, including 17 new molecules among the 50 structures reported (Djinni et al 2019;Lahoum et al 2019). Actinobacteria isolated from arid and other extreme ecosystems remain the inexhaustible source of new antimicrobials, offering an opportunity to get new bioactive metabolites (Djinni et al 2019).…”

Climatic Zone and Soil Properties Determine the Biodiversity of the Soil Bacterial Communities Associated to Native Plants from Desert Areas of North-Central Algeria

“…This could also be attributed to the abundance of Actinobacteria, that are known to produce IAA, as previously shown by literature papers [ 55 , 56 ]. Studies on various desert environments, reveal also both the antimicrobial [ 2 , 57 ] and the plant growth promoting properties [ 58 ] for the communities of Actinobacteria. These bacterial performances could explain the survivability potentials of the plant species present in the analyzed sites, during low water and nutrient availability.…”

“…Extending over a surface reaching about 2.38 million km 2 , Algeria is the largest country in Africa where three types of climates coexist: a Mediterranean climate which is typical of the Coastal zones and Northern mountains, a semi-arid climate that occurs in the highlands and an arid climate which is associated with the Sahara desert [2]. Based on the aridity index (AI), defined as the ratio between average annual precipitation amount (P) and potential evapotranspiration amount, Algeria is characterized by semi-arid and arid sites located in the North of the country, and occupying 20% of the territory and hypersaline zones in the center and South of Algeria, representing 80% of the country.…”

Natural Compounds as Antimicrobial Agents

“…Further in the issue, you will also find two interesting reviews on the conventional meaning of "Natural Compounds" and conventional antibiotics, between which the borders are very thin. So thin, in fact, that many believe in the richness of extreme ecosystems for finding Actinobacteria-producing antibiotics [4], and in the use of secondary metabolites from Burkholderia as new sources in antibiotic development [5].…”