Production of biosurfactants from vine-trimming shoots using the halotolerant strain Bacillus tequilensis ZSB10

• Residues of vine-trimming shoots can be used as carbon sources for BS production.
• The halotolerant ZSB10 strain produced BS using hydrolyzed vine-trimming shoots.
• BS production was enhanced when MSM medium was added to HC and CH hydrolyzates.
• A higher yield of extracellular BS than cell-bond BS was obtained by B. tequilensis.
• Extracellular BS had better surfactant and emulsifying properties than cell-bond BS.

The strain Bacillus tequilensis ZSB10, isolated from Mexican brines, was able to grow and produce extracellular and cell-bound biosurfactants using nine culture broths formulated from hydrolyzates obtained from the cellulosic and hemicellulosic fractions of vine-trimming wastes. The results confirm its halotolerance since it managed to grow both in the presence and absence of salts. It also was able to consume sugars such as glucose and xylose. The process was then scaled up into a 2-L bioreactor using the mixture of hemicellulosic (50%) and cellulosic hydrolyzate (50%) supplemented with mineral salt medium as culture medium at different biomass concentrations. Crude extracellular biosurfactant yielded 1.52 g/L and lowered the surface tension to 38.6 mN/m with a critical micelle concentration of 177.14 mg/L. Furthermore, it was able to emulsify with kerosene after 24 h (E24 = 47%). Crude cell-bound biosurfactant only yielded 0.0783 g/L and showed lower emulsifying characteristics than extracellular biosurfactant (E24 = 41% with kerosene).