A novel static cultivation of bacterial cellulose production from sugar beet molasses: Series static culture (SSC) system

In bacterial cellulose (BC) production, we developed a new static cultivation system named series static culture (SSC) to eliminate air limitation problem encountered in conventional static culture (CSC). In SSC system, the fermentation broth at the bottom of BC pellicle produced in initial culture medium is transferred to the next empty sterile culture medium at the end of a certain fermentation period. This procedure was performed until BC production ceased. Fermentation experiments were carried out using Gluconacetobacter xylinus NRRL B-759 and sugar beet molasses at 30 °C and initial pH 5. Also, some quality parameters of produced BC pellicles were determined. Final pH at the stages of SSC system was higher that of the initial pH due to sugar content (sucrose) of molasses and microorganism used. Total BC production increased with increasing sugar concentration in SSC. As a result, an increase of 22.02 % in BC production was achieved using developed SSC. FT-IR spectra of all BC pellicles produced were typical spectra. The absorption bands at the relevant wavenumbers identify the mode of vibrations of the created chemical bonds arising at the BC surface such as OH, CH, H-O-H, C-O-C, and C-OH. XRD analyses showed that the crystallinity index values of BC obtained from CCS and SSC were high. The form of produced all BC pellicles is generally Cellulose I. Removal of surface moisture and depolymerisation of carbon skeleton were determined from TGA-DTA thermograms. SEM images showed that the BC samples produced had nano-sized cellulose fibrils which were aggregated in fermentation media containing molasses. Finally, the BC samples, especially in molasses media, having high mechanical strength and WHC were found.

A Modified, Efficient and Sensitive pH Indicator Dye Method for the Screening of Acid-Producing Acetobacter Strains Having Potential Application in Bio-Cellulose Production

It is imperative that promising bacterial cellulose-producing bacteria mainly belongs to genera Acetobacter (acid-producing bacteria). In order to screen cellulose-producing Acetobacter, the isolated cultures from vinegar/rotten fruits were inoculated in Hestrin-Schramm (HS) medium containing ethanol and CaCO₃. After the desired incubation, the positive cultures form a zone, which is observed around the bacterial growth, resulted from the solubilization of CaCO₃ by acetic acid produced from the oxidation of ethanol during fermentation. However, in this method, the clarity of the solubilized zone is not very sharp and distinct. In the present, investigation, an improved method for screening, of the microorganisms producing acetic acid has been developed. In this method, methyl red (MR) is incorporated as a pH indicator in HS medium containing ethanol and CaCO₃. Plates containing MR at alkaline pH are yellow and turn dark red at acidic pH. Thus, a distinctive, clear zone is formed around bacterial colonies producing acetic acid and is easy to differentiate between acid producers and non-producers. The present method is more rapid, accurate, and sensitive and can be successfully be used for the detection of acetic acid-producing bacteria particularly for the screening of potent cellulose producer Acetobacter sp.

Comparison of bacterial nanocellulose produced by different strains under static and agitated culture conditions

Bacterial nanocellulose (BNC) has many advantages over plant cellulose, which make it widely used in many fields, especially in the food industry. In this study, three strains including BCA263, BCC529, and P1 were selected for characteristics analysis of BNCs under static and agitated culture conditions. The BNCs produced under static culture condition were in the shape of uniform membrane, while BNCs produced under agitated culture were in form of small agglomerates and fragments. BCA263 and BCC529 strains were more suitable for static culture, while P1 strain was more suitable for agitated culture. BNCs produced under static culture condition exhibited higher crystallinity, stronger tensile strength, denser network structure, higher temperature resistance and good flame retardancy; while BNCs produced under agitated culture condition exhibited larger porous and lower crystallinity. Furthermore, BNCs produced under agitated culture condition were more suitable as a stabilizer of coffee milk beverage.

Production of nano bacterial cellulose from beverage industrial waste of citrus peel and pomace using Komagataeibacter xylinus

Bacterial cellulose (BC) is a high-purity and robust cellulose that is utilised in medicine, consumer goods, and industrial practices. The present study aimed to investigate the suitability of beverage industrial waste for the production of BC by Komagataeibacter xylinus CICC No. 10529 and to study the structural properties of BC films in both citrus peel and pomace enzymolysis (CPPE) and Hestrin-Schramm (HS, Hestrin & Schramm, 1954) media. Under similar experimental conditions, the yield of BC from CPPE medium was 5.7±0.7g/L, which was higher than from HS medium (3.9±0.6g/L). To evaluate the structure of BC, fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and colour evaluation using a chroma meter were utilised. The average diameters of BC, obtained from CPPE and HS mediums, were 50nm and 60nm, respectively. The crystallinity index of BC from the CPPE medium was approximately 63%, which was lower than BC produced from the HS medium (65%). The two varieties of BC showed no significant differences in relation to their colour parameters. Therefore, BC production from CPPE medium had similar properties to BC from HS medium, but it is more environmentally friendly and cheaper to produce.