Синтез молочной кислоты грибом Rhizopus oryzae F-1030 на питательных средах из сульфитных щелоков

Abstract

Lactic acid is an industrially important product with an expanding consumer market. However, lactic acid production and isolation methods used at the present time are not effective enough, lead to the formation of large amounts of polluting waste and their recycling is economically unproftable. At the same time, a half of the worldʼs lactic acid production is carried out by the microbiological method based on the fermentation of such costly sugarcontaining substrates as sucrose, molasses, treacle, sugar syrup, etc. These sugar-containing substrates usage signifcantly increases the fnal product cost. In order to solve the economicand environmental problems of lactic acid production it is necessary to revise the current raw material source and put cheaper and readily available sources of carbohydrates, such as sulphite liquor formed during sulphite pulping, into the lactic acid production. In turn to enhance the economic efciency of the Russian pulp and paper production it is necessary to use such paper production by-products as sulphite liquor to the fullest extent possible. Sulphite liquor is a chemical complex of inorganic and organic compounds such as monoand oligosaccharides. The article considers the dependence of the output of lactic acidsynthesized on the sulphite liquor medium by the fngus R. oryzae F-1030 on the used method of cultivation. In case of the semicontinuous culture method, the culture liquid was replaced with the similar volume of the sterile growth medium with the fungus biomass saving when the sugars in the medium were depleted. In case of the batch culture method, the synthesized lactic acid was precipitated with calcium hydroxide and the reducing substances recovery in the culture liquid was achieved by adding concentrated sulphite liquor when the sugars in the medium were depleted. The study demonstrates that the largest amount of synthesized lactic acid is obtained when using the semicontinuous method for cultivation of the fngus on the sulphite liquor medium prepared according to the technology recommended in the industry during preparation growth media for yeast cultivation. If it is impossible to carry out a full industrial pre-treatment of sulphite liquor, it is recommended to use the batch culture method for the fungus in order to obtain more synthesized lactic acid. For citation: Mingazova L.A., Kanarsky A.V., Kryakunova E.V., Kanarskaya Z.A. Lactic Acid Synthesis by the Fungus Rhizopus Oryzae F-1030 on Growth Media Based on Sulphite Liquors. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 2, pp. 146–158. DOI: 10.37482/0536-1036-2020-2-146-158