Rare Halophilic Nocardiopsis from Algerian Saharan Soils as Tools for Biotechnological Processes in Pharmaceutical Industry

Abstract

The Sahara Desert, one of the most extreme ecosystems in the planet, constitutes an unexplored source of microorganisms such as mycelial bacteria. In this study, we investigated the diversity of halophilic actinobacteria in soils collected from five regions of the Algerian Sahara. A total of 23 halophilic actinobacterial strains were isolated by using a humic-vitamin agar medium supplemented with 10% NaCl. The isolated halophilic strains were subjected to taxonomic analysis using a polyphasic approach, which included morphological, chemotaxonomic, physiological (numerical taxonomy), and phylogenetic analyses. The isolates showed abundant growth in CMA (complex medium agar) and TSA (tryptic soy agar) media containing 10% NaCl, and chemotaxonomic characteristics were consistent with their assignment to the genus Nocardiopsis. Analysis of the 16S rRNA sequence of 23 isolates showed five distinct clusters and a similarity level ranging between 98.4% and 99.8% within the Nocardiopsis species. Comparison of their physiological characteristics with the nearest species showed significant differences with the closely related species. Halophilic Nocardiopsis isolated from Algerian Sahara soil represents a distinct phyletic line suggesting a potential new species. Furthermore, the isolated strains of halophilic Nocardiopsis were screened for their antagonistic properties against a broad spectrum of microorganisms by the conventional agar method (agar cylinders method) and found to have the capacity to produce bioactive secondary metabolites. Except one isolate (AH37), all isolated Nocardiopsis showed moderate to high biological activities against Pseudomonas syringae and Salmonella enterica, and some isolates showed activities against Agrobacterium tumefaciens, Serratia marcescens, and Klebsiella pneumoniae. However, no isolates were active against Bacillus subtilis, Aspergillus flavus, or Aspergillus niger. The obtained finding implies that the unexplored extreme environments such as the Sahara contain many new bacterial species as a novel drug source for medical and industrial applications.

New Alkali-tolerant and Halo-tolerant Nocardiopsis Strain B20 from Algerian Saharan Soil: Isolation, Taxonomy, and Antifungal Activity

“…It grew under various NaCl concentrations (up to 10 %), similar to halo-tolerant strains like N. salina [33]. The strain utilized sixteen carbon sources (out of twenty tested), highlighting a remarkable versatility like several Nocardiopsis strains isolated from Algerian Saharan Soils [34]. However, it only degraded three organic acids (out of nine tested).…”

“…The ability of Nocardiopsis sp. B20 to grow under extreme pH and NaCl conditions and utilization of a variety of carbon sources highlight its potential for application as a promising candidate for biotechnological and agricultural applications [5,34]. Moreover, the ability to exhibit metabolic flexibility is a crucial trait for soil microorganisms, including species of Nocardiopsis.…”

“…The genus Nocardiopsis is known for its ability to produce a wide variety of secondary metabolites, which account for its diverse biological activities. These secondary metabolites have shown promise mainly as cytotoxic compounds, anticancer, antimicrobial agents, tumor promoters, kinase, and Pglycoprotein inhibitors, immunoregulators, plant growth promoters, and natural products with other multiple bioactivities [4,34,[39][40][41]. Nocardiopsis species have also been identified as potential sources of diverse and novel extracellular enzymes [42].…”