Screening for genes coding for putative antitumor compounds, antimicrobial and enzymatic activities from haloalkalitolerant and haloalkaliphilic bacteria strains of Algerian Sahara Soils

Abstract

Extreme environments may often contain unusual bacterial groups whose physiology is distinct from those of normal environments. To satisfy the need for new bioactive pharmaceuticals compounds and enzymes, we report here the isolation of novel bacteria from an extreme environment. Thirteen selected haloalkalitolerant and haloalkaliphilic bacteria were isolated from Algerian Sahara Desert soils. These isolates were screened for the presence of genes coding for putative antitumor compounds using PCR based methods. Enzymatic, antibacterial, and antifungal activities were determined by using cultural dependant methods. Several of these isolates are typical of desert and alkaline saline soils, but, in addition, we report for the first time the presence of a potential new member of the genus Nocardia with particular activity against the yeast Saccharomyces cerevisiae. In addition to their haloalkali character, the presence of genes coding for putative antitumor compounds, combined with the antimicrobial activity against a broad range of indicator strains and their enzymatic potential, makes them suitable for biotechnology applications.

Figure 1

Location of the sampled sites from Algerian Sahara Desert. Djelfa: 35°16′47.5′′N 3°43′25.4′′E; Biskra: 34°11′01.1′′N 6°07′21.8′′E; Ouargla: 33°29′ 28.85 N 5°59′10.52′′ E; Tamanrasset 23°00′30.01′′N 5°13′33.32′′ E; In Salah: 27°11′31.60′′ N 2°27′12.52′′ E; Adrar: 27°44′48.14′′ N 0°16′10.21′′ W; Bechar: 30°51′25.71′′ N 1°59′58.56′′ W.

Figure 2

Macroscopic morphology (left) on ISP2 and microscopic filamentous morphology (right) of three strains of this study. (a) Strain IG6: spiral chain of spores on aerial mycelium. (b) Strain Bisk2: nocardioform mycelium. (c) Strain M5A: long straight chains of spores on aerial mycelium.

Figure 3

Molecular phylogeny of thirteen selected bacteria and the most related type strains species using partial 16S rRNA sequences. The evolutionary distances were computed using the maximum composite likelihood method and are in the units of the number of base substitutions per site. Tree topology was constructed using MEGA 4.0. Bootstrap values (n = 1000 replicates) were indicated at the nodes. Escherichia coli KCTC2441 sequence was added as an out group for this tree.

Figure 4

Agarose gel electrophoresis of PCR products from genomic DNA of six strains of the present study with selective fragments amplification range 500–700 bp using primers: (a) Glu1/Glu2, (b) StaDVF/StaDVR, and (c) AuF3/AuF4. M: 1 kb Plus DNA ladder; W: water control.

Figure 5

Antimicrobial activity of some strains among the selected strains: (a) antibacterial activity against Staphylococcus aureus, (b) antifungal activity against Fusarium oxysporum f. sp. albedinis, and (c) antifungal activity of the strain Nocardia sp. (Bisk2) against the yeast Saccharomyces cerevisiae.

Figure 6

Enzymatic activities of some strains among the selected strains. (a) Proteases (caseinase), (b) lipases, and (c) amylases.