Climate change predictions indicate that water supplied by rainfall for agriculture is decreasing and several countries face an ever-increasing rate of desertification [1]. Water stress is a critical issue for plant growth in arid and semi- arid soils. Therefore, novel eco-friendly products are needed to increase water avaibility. Extremophilic bacteria, inhabiting extremely hot environments, developed strategies to cope the effects of high temperatures (i.e. denaturation of proteins or DNA, and dessiccation), producing thermostable polymers, such as surfactants (BS) and exopolysaccharides (EPS) [2]. In this work, the hydrating capabilities of the surfactin-like lipopeptide (BS-SBP3) and the exopolysaccharide (EPS-SBP3) produced by the polyextremophilic Bacillus horneckiae SBP3 DSM 103063 of shallow hydrothermal vent origin, were investigated evaluating: (i) their wetting properties by contact angle; (ii) their moisture sorption capacities by gravimetric method, and (iii) their hydration states (0–160% w/w) by spectroscopic analysis. BS-SBP3 reduced the contact angle of water on a hydrophobic polystyrene surface (from θ = 81.7° to θ = 51.3°) more than EPS-SBP3 (from θ = 81.7° to θ = 72.9°), indicating that BS-SBP3 improved more efficiently the wettability of the hydrophobic surface. EPS-SBP3 absorbed water more than BS-SBP3, increasing its weight threefold (from 10 to 30.1 mg) after 36 hours of exposure to 100% humidity. The spectroscopic analysis revealed that each polymer possessed different water retention capacity, being the BS more efficient (up to 80%) than the EPS (48%). Moreover, both polymers resulted no toxic up to 10 mg/mL, as revealed by bioluminescent assay with Vibrio harveyi G5, indicating high eco-compatibility. Due to their different surface properties, hydration capacity, low toxicity and biodegradability, the two biopolymers represent an ecological alternative to their chemical counterparts to contrast the dehydration in arid soils and optimize water uses in agriculture.

Hydration capacity of polymers from the marine polyextremophilic Bacillus horneckiae SBP3 and their potential applications in arid or semi-arid soil

E. Agostino;A. Macri';V. Zammuto;M. T. Caccamo;S. Magazu';C. Gugliandolo
2023-01-01

Abstract

Climate change predictions indicate that water supplied by rainfall for agriculture is decreasing and several countries face an ever-increasing rate of desertification [1]. Water stress is a critical issue for plant growth in arid and semi- arid soils. Therefore, novel eco-friendly products are needed to increase water avaibility. Extremophilic bacteria, inhabiting extremely hot environments, developed strategies to cope the effects of high temperatures (i.e. denaturation of proteins or DNA, and dessiccation), producing thermostable polymers, such as surfactants (BS) and exopolysaccharides (EPS) [2]. In this work, the hydrating capabilities of the surfactin-like lipopeptide (BS-SBP3) and the exopolysaccharide (EPS-SBP3) produced by the polyextremophilic Bacillus horneckiae SBP3 DSM 103063 of shallow hydrothermal vent origin, were investigated evaluating: (i) their wetting properties by contact angle; (ii) their moisture sorption capacities by gravimetric method, and (iii) their hydration states (0–160% w/w) by spectroscopic analysis. BS-SBP3 reduced the contact angle of water on a hydrophobic polystyrene surface (from θ = 81.7° to θ = 51.3°) more than EPS-SBP3 (from θ = 81.7° to θ = 72.9°), indicating that BS-SBP3 improved more efficiently the wettability of the hydrophobic surface. EPS-SBP3 absorbed water more than BS-SBP3, increasing its weight threefold (from 10 to 30.1 mg) after 36 hours of exposure to 100% humidity. The spectroscopic analysis revealed that each polymer possessed different water retention capacity, being the BS more efficient (up to 80%) than the EPS (48%). Moreover, both polymers resulted no toxic up to 10 mg/mL, as revealed by bioluminescent assay with Vibrio harveyi G5, indicating high eco-compatibility. Due to their different surface properties, hydration capacity, low toxicity and biodegradability, the two biopolymers represent an ecological alternative to their chemical counterparts to contrast the dehydration in arid soils and optimize water uses in agriculture.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3304869
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