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Bacterial nanocellulose (BNC) whose biosynthesis fully conforms to green chemistry principles arouses much interest of specialists in technical chemistry and materials science because of its specific properties, such as nanostructure, purity, thermal stability, reactivity, high crystallinity, etc. The functionalization of the BNC surface remains a priority research area of polymers. The present study was aimed at scaled production of an enlarged BNC sample and at synthesizing cellulose nitrate (CN) therefrom. Cyclic biosynthesis of BNC was run in a semisynthetic glucose medium of 10−72 L in volume by using the Medusomyces gisevii Sa-12 symbiont. The most representative BNC sample weighing 6800 g and having an α-cellulose content of 99% and a polymerization degree of 4000 was nitrated. The nitration of freeze-dried BNC was performed with sulfuric-nitric mixed acid. BNC was examined by scanning electron microscopy (SEM) and infrared spectroscopy (IR), and CN was explored to a fuller extent by SEM, IR, thermogravimetric analysis/differential scanning analysis (TGA/DTA) and 13C nuclear magnetic resonance (NMR) spectroscopy. The three-cycle biosynthesis of BNC with an increasing volume of the nutrient medium from 10 to 72 L was successfully scaled up in nonsterile conditions to afford 9432 g of BNC gel-films. CNs with a nitrogen content of 10.96% and a viscosity of 916 cP were synthesized. It was found by the SEM technique that the CN preserved the 3D reticulate structure of initial BNC fibers a marginal thickening of the nanofibers themselves. Different analytical techniques reliably proved the resultant nitration product to be CN. When dissolved in acetone, the CN was found to form a clear high-viscosity organogel whose further studies will broaden application fields of the modified BNC.

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Bacterial cellulose (BC) consists in a highly crystalline nanopolymer whose potential for application in both traditional and new industries is significant due to its unique physico-mechanical properties. In scaled BC biosynthesis processes, the use of microorganism consortia characterised by their adaptability and synergistic effects when coordinating substrate consumption appears to be promising. In the present work, the effect of inoculum dosage on BC yield during Medusomyces gisevii Sa-12 symbiotic culture on a glucose medium under optimal conditions is studied in detail. Two available methods were chosen for quality control of the BC: scanning electron microscopy, presenting an express method for confirming the origin of cellulose; and the degree of polymerisation in terms of a common method for controlling the quality of cellulose. Four experiments were carried out for the producer introduction with a dosage of 5, 10, 15 and 20% vol.. Use of the Medusomyces gisevii Sa-12 symbiotic culture provided the greatest number of acetic acid bacteria and the highest BC yield (7.5-8.0%) with an inoculum dosage of 10-20% vol. At the same time, an inoculum dosage of 20% vol. allowed the culture time to be halved, while an inoculum dosage of 5% vol. appears to be insufficient. All inoculum dosage variants were determined to provide the same three-dimensional cross-linked microfibrillar structure of BC samples. The degree of polymerisation (DP) of BC samples was first established to depend on the dosage of the inoculum and the duration of BC biosynthesis. Thus, the biosynthesis process can be controlled using such a simple parameter as inoculum dosage and BCs can be synthesised directionally with a given DP. The inoculum dosage of 10% vol. was established as providing the highest possible DP of BC (value of 5000), decreasing slightly during prolonged culture. For citation: Skiba E.A., Baibakova O.V., Gladysheva E.K., Budaeva V.V. Study of the influence of Medusomyces gisevii Sa-12 inoculum dosage on bacterial cellulose yield and degree of polymerisation. Izvestiya Vuzov. Исследование влияния дозировки инокулята Medusomyces gisevii Sa-12 на выход и степень полимеризации бактериальной целлюлозы © Е.А. Скиба, О.В. Байбакова, Е.К. Гладышева, В.В. Будаева Институт проблем химико-энергетических технологий СО РАН, г. Бийск, Российская Федерация Резюме: Бактериальная целлюлоза (БЦ) является высококристаллическим нанополимером с уникальными физико-механическими свойствами, поэтому обладает превосходным потенциалом применения как в традиционных, так и в новых отраслях. В масштабированных процессах биосинтеза БЦ перспективно применение консорциумов микроорганизмов, характеризующихся адаптивностью и обла-Skiba E.A., Baibakova O.V., Gladysheva E.K., et al. Study of the influence… Скиба Е.А., Байбакова О.В., Гладышева Е.К. и др. Исследование влияния… ФИЗИКО-ХИМИЧЕСКАЯ БИОЛОГИЯ / PHYSICOCHEMICAL BIOLOGY 421 дающих синергетическими эффектами в координирующем потреблении субстрата, поэтому в данной работе используется симбиотическая культ...