Tequila Agave Bagasse Hydrolysate for the Production of Polyhydroxybutyrate by Burkholderia sacchari

Abstract

Tequila agave bagasse (TAB) is the fibrous waste from the Tequila production process. It is generated in large amounts and its disposal is an environmental problem. Its use as a source of fermentable sugars for biotechnological processes is of interest; thus, it was investigated for the production of polyhydroxybutyrate (PHB) by the xylose-assimilating bacteria Burkholderia sacchari. First, it was chemically hydrolyzed, yielding 20.6 g·L−1 of reducing sugars, with xylose and glucose as the main components (7:3 ratio). Next, the effect of hydrolysis by-products on B. sacchari growth was evaluated. Phenolic compounds showed the highest toxicity (> 60% of growth inhibition). Then, detoxification methods (resins, activated charcoal, laccases) were tested to remove the growth inhibitory compounds from the TAB hydrolysate (TABH). The highest removal percentage (92%) was achieved using activated charcoal (50 g·L−1, pH 2, 4 h). Finally, detoxified TABH was used as the carbon source for the production of PHB in a two-step batch culture, reaching a biomass production of 11.3 g·L−1 and a PHB accumulation of 24 g PHB g−1 dry cell (after 122 h of culture). The polymer structure resulted in a homopolymer of 3-hydroxybutyric acid. It is concluded that the TAB could be hydrolyzed and valorized as a carbon source for producing PHB.

Biotechnological Approaches to Generate Biogenic Solvents and Energy Carriers from Renewable Resources

“…Noteworthy, not only the hexose glucose was readily consumed by the strain, but also the pentose xylose was completely depleted until the end of the process [53]. This procedure is analogous to production of other value-added bioproducts from agave bagasse, as shown, e.g., in 2019 by González-García et al for PHA biopolyester production [54]. In addition, sweet sorghum juice, an inexpensive, sugar-rich raw material, was applied for 2,3-BD biosynthesis by Yuan et al, who used a Serratia marcescens strain, another facultative anaerobe.…”

Polyhydroxyalkanoates Production: A Challenge for the Plastic Industry

“…They used acid hydrolysis to obtain xylose and Burkholderia sacchari to synthesize PHB with a total biomass concentration of 6.13 g/L and an accumulation of 23% in cells. 164 It was also observed that the pretreatment of cellulosic biomass in combination with enzymes led to a higher yield of PHB during the microbial fermentation than that obtained from the biomass only pretreated with sulfuric acid. 136 This could be ascribed to inhibition effects derived from the formation of byproducts due to sugar degradation during acid hydrolysis.…”

“…In 2019 González-García et al reported the use of blue agave bagasse as a lignocellulosic source to produce PHB. They used acid hydrolysis to obtain xylose and Burkholderia sacchari to synthesize PHB with a total biomass concentration of 6.13 g/L and an accumulation of 23% in cells . It was also observed that the pretreatment of cellulosic biomass in combination with enzymes led to a higher yield of PHB during the microbial fermentation than that obtained from the biomass only pretreated with sulfuric acid .…”

Advances in Polyhydroxyalkanoate (PHA) Production, Volume 2

“…After the removal of those inhibiting phenolics by convenient methods, the detoxified hydrolysate was used as feedstock for PHB production in a two-step batch cultivation process, resulting in a PHB concentration of almost 3 g/L after 122 h of cultivation. This study provides another example how PHA production can be integrated into the production lines of existing agricultural and food-processing industries in order to upgrade existing waste streams to feedstocks for biopolymer production [12].…”