Исследование биосинтеза бактериальной наноцеллюлозы продуцентом Medusomyces gisevii Sa-12 на ферментативном гидролизате продукта щелочной делигнификации мискантуса

Abstract

A high demand for bacterial nanocellulose (BNC) in various economic sectors has resulted in intensification of studies aimed at searching for ways of reducing the cost of its production. BNC on an industrial scale is obtained using synthetic nutrient media, the cost of which may amount to 30–60% of the total cost of the process. Therefore, the study of BNC biosynthesis using low-cost nutrient media, such as food and cellulosic waste and other alternative sources of raw materials, seems to be highly relevant. The biomass of miscanthus currently used as a raw material for biofuels may become such an alternative source. Miscanthus is characterised by availability, low cost and annual renewability on an industrial scale. This study was aimed at investigating the BNC biosynthesis process from the enzymatic hydrolyzate obtained by alkaline delignification of miscanthus. The delignification process involved treatment of the plant with a dilute sodium hydroxide solution at ambient pressures. Enzymatic hydrolysis of the obtained substrate was carried out in a 11L-fermenter. For the first time, BNC was successfully obtained in a nutrient medium from an enzymatic hydrolyzate produced by alkaline delignification of miscanthus. The symbiotic culture of Medusomyces gisevii Sa-12 characterised by a high adaptive potential was used as a producer. The maximum specific growth rates were 0.360 and 0.384 day -1 for yeast and acetic acid bacteria, respectively. Consumption of reducing substances was observed to proceed in two stages: the rate constant of substrate utilisation at the first and the second stages were equal to 0.464 day and 0.034 day -1 , respectively. The highest yield of BNC was 5.14% on the 14th day of cultivation, which is 1.8 times lower than that on a synthetic nutrient medium. Although the nutrient medium of the enzymatic hydrolyzate obtained by alkaline delignification of miscanthus is not biologically pure, Medusomyces gisevii Sa-12 shows a high technological potential and ability to synthesize a chemically pure BNC even under adverse conditions.