Читать книгу Biosurfactants for a Sustainable Future - Группа авторов - Страница 55

Lignocellulosic substances comprise cellulose, lignin, and hemicellulose. The paper industry primarily utilizes cellulose from lignocellulose and applies a variety of techniques to eliminate certain fiber elements (such as hemicellulose and lignin), as a result of which these other elements remain, more often than not, unused, thus becoming waste products. Furthermore, in bioethanol research, various pretreatment techniques are used to extract cellulose for fermentation, with very little attention paid to hemicellulose and lignin. Such pretreatment technologies are, therefore, only midway to becoming primary methods of refining lignocellulosic materials, and only realize the use of one or two key elements, whereas other contents are wasted [35, 129, 130]. Portilla‐Rivera et al. [131] examined Lactobacillus pentosus's ability for biosurfactant and lactic acid production in fermentation medium composed with 10.0 g/l of the byproduct of corn wet‐milling, 10 g/l of yeast extract, and hydrolyzed pomace (10.8% cellulose, 11.2% hemicellulose, and 51% lignin). They obtained 5.5 g/l of lactic acid and 4.8 mg/l of cell‐bound biosurfactant. In a subsequent study, the sustainability and emulsification of biosurfactants obtained from L. pentosus from distilled pomace hydrolysates, walnut, and hazelnut shell‐based fermentation media were also examined by Portilla‐Rivera et al. [131]. The emulsion density reported was 14.1% for gasoline and 27.2% for kerosene, which was higher than those produced for industrial surfactin. Cortés‐Camargo et al. [132] used the ZSB10 strain of Bacillus tequilensis, separated from Mexican brine, for intracellular and extracellular biosurfactant production. Their findings revealed that the extracellular biosurfactant production using lignocellulosic waste was 1.52 g/l with a surface tension reduction of 38.6 mN/m and 177.0 mg/l CMC value. The intracellular biosurfactant produced was only 0.078 g/l in quantity and exhibited a lesser EI (41%) than an extracellular EI (47%). Jokari and group [133] reported the impact of aeration levels on B. subtilis ATCC 6633 growth and the amount of biosurfactant produced in a miniaturized bioreactor ventilated flask. In the ideal conditions where the filling and shaking rates were 15 ml and 300 rpm, the maximum biosurfactant content (0.0485 g/l/h) was achieved. Their findings indicated the noticeable increase in surfactin productivity under environments that were not oxygen‐limiting.

These studies have shown that lignocellulosic compounds and waste products could be considered as raw materials for the production of biosurfactants due to their low processing costs and higher nutrient quality. The results of these studies also show that lignocellulosic waste can be a potential carbon source for fermentation. The biosurfactant synthesis of these industrial byproducts offers a promising financial advantage that can be used to achieve cost savings over the production of synthetic surfactants.