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2 Ecological Engineering & Environmental Technology

2 2024

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Study of the Physicochemical Properties of Streptomyces Cell Surface and their Relationship with Soil Salinity of Origin

Zanane Chorouk, Mazigh Doha, Mitro Soukaina, Hakim Taoufik, Lekchiri Souad, El Othmany Rabha, El Louali Mostafa, Latrache Hassan, Zahir Hafida

Ecological Engineering & Environmental Technology

2024

Vol. 25, iss. 10

31--43

Physicochemical properties of the bacterial surface are involved in several interfacial phenomena, such as microbial adhesion. Ecology Soil salinity is a crucial parameter for the distribution of Streptomyces. The objective of this study was to investigate the impact of NaCl on the hydrophobicity and electron donor/acceptor characteristics of the cell surface of fourteen Streptomyces strains isolated from soils of the Beni Amir region (Morocco) with different salinities. The physicochemical properties of the surface were evaluated using the MATS (microbial adhesion to solvents) method at two concentrations of NaCl (0.1 M and 1.2 M). The results obtained show a significant change from hydrophilic to hydrophobic character. In particular, the Streptomyces lilaceus A53 strain showed the lowest variation (4.21%). On the other hand, the Streptomyces albogriseolus A65 strain presented the greatest variation (86.15%). These changes were observed when the salt concentration increased significantly from 0.1 M to 1.2 M NaCl. The electron donor/acceptor character systematically decreases and even becomes null for the majority of strains. Furthermore, a strong correlation between cell surface hydrophobicity and salinity of the original soil was observed with MATS at 1.2 M NaCl. This study highlighted the crucial importance of the NaCl concentration in the modulation of the physicochemical properties of the surface of Streptomyces bacteria.

Effect of Growth Medium Composition on the Physicochemical Surface Properties of Pseudomonas savastanoi, the Agent of Olive Tuberculosis

Mitro Soukaina, El Othmany Rabha, Hakim Taoufik, Zanane Chorouk, Lekchiri Souad, Mazigh Doha, El Louali Mostafa, Latrache Hassan, Zahir Hafida

Ecological Engineering & Environmental Technology

2024

Vol. 25, iss. 8

72--78

Research into the formation of Pseudomonas savastanoi biofilms on olive trees is essential to prevent infections that induce tumour formation and damage tree health. To prevent the development of P. savastanoi biofilms, it is crucial to comprehend the factors influencing its adhesive behaviour. This research analysed the physicochemical properties of P. savastanoi in two types of media. P. savastanoi was cultivated in two media: nutrient agar (NA) and King B (KB), in solid and liquid forms. Wettability (θw), electron acceptor (γ+) electron donor (γ- ) properties, and surface free energy (ΔGiwi) are evaluated by contact angle measurements. The obtained results indicated that in solid media (NA and KB), P. savastanoi exhibited hydrophobic surface (𝜃WNA = 82.23°; 𝜃WKB= 94.9°), with strong electron donor (γNA− = 43.54 mJ.m-2; γKB− = 58.34 mJ·m-2) and mild electron acceptor (γNA+ = 0.32 mJ.m-2; γKB+ = 0.52 mJ·m-2) properties, along with negative surface free energy (ΔGiwiNA-76.13 mJ·m-2; ΔGiwiKB= -65.33 mJ·m-2. Conversely, in liquid media (NB and KB), the surface of P. savastanoi was generally hydrophilic (𝜃WNB= 55.43°; 𝜃WKB = 64.43°), with strong electron donor (γNB− = 29.23 mJ.m-2; γKB− = 41.38 mJ.m-2) and a surface free energy that registers as positive. Modification of the growth medium composition led to minor variations in P. savastanoi hydrophobicity and surface free energy. By understanding the factors involved in this adhesive behaviour, ecological methods to protect crops and contribute to more efficient environmental management and conservation of natural resources can be developed.