Development of a Cost-Effective Culture Medium for the Bacterial Cellulose Production Using Food Industry Wastes

Abstract   Background and Objective: Use of bacterial cellulose has been interested in various industries, especially medical and pharmaceutical industries, due to its unique characteristics, compared to plant cellulose. However, bacterial cellulose production costs have limited its industrial uses, compared to plant cellulose. Decreasing costs of the culture media is one of the effective parameters for the industrial production of bacterial cellulose. This is the first report on combination of vinasse and glucose syrup as a bacterial cellulose culture medium. Material and Methods: Two inexpensive culture media were developed for high-level production of bacterial cellulose based on food industrial wastes of corn steep liquor-glucose and vinasse-glucose syrups. Concentrations of glucose syrup and corn steep liquor as a culture medium and concentrations of vinasse and glucose syrup as another culture medium were optimized using response surface method with central composite design to maximize bacterial cellulose production yields. Results and Conclusion: Under the optimal conditions after seven days, 14.8 and 13.3 g.l-1 dry bacterial cellulose were achieved in corn steep liquor-glucose syrup and vinasse-glucose syrup respectively. Yield of produced bacterial cellulose from these two cost-effective culture media was one of the highest values reported for bacterial cellulose. Furthermore, the produced bacterial cellulose was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Conflict of interest: The authors declare no conflict of interest

Increasing Protein Content of Tomato Pomace using Solid-State Fermentation with Industrial Bakery Yeasts: Increasing the protein content of tomato pulp by solid-state fermentation

Background and Objective: Tomato pomace as the major waste of tomato paste can be used in food formulation due to its nutritional and technological characteristics. The aim of this study was to create a cheap simple method to increase the protein content of tomato pomace, which could be used as a cheap and more efficient food source for livestock and poultry. Material and Methods: The study was carried out in three stages: 1) selection of further appropriate yeasts by assessing effects of two types of avaiable Saccharomyces cerevisiae and Saccharomyces bulardi industrial yeasts and fermentation time in the moisture content of  5% tomato pomace with particle size of less than 500 μm on the protein content of tomato pomace, 2) asessment of optimum conditions for increasing the protein content of tomato pomace by assessing effects of four parameters of the quantity of the yeasts, initial moisture content, substrate particle size and cultivation time in three levels, based on the Taguchi method in nine experiments in laboratory scale, 3) increase of the protein content of tomato pomace in bench scale tray bioreactor by investigation of three factor substrate depth, distance between trays and substrate particle size in three levels and one aeration factor in two levels based on the Taguchi method.   Results and Conclusion: Saccharomyces cerevisiae and 5-d cultivation time were chosen to continue the study. Under optimal conditions in laboratory scale, 0.03 g dry yeast/g tomato pomace of yeast, moisture content of 70% (w w-1), particle size of less than 150–250 μm (mesh 100) and process time of 5 d, protein content of 24.72% with fat content of 3.29%, ash of 16.45% and carbohydrate of 55.52% (w w-1) were achieved. Under optimal conditions, including bed depth of 1.2 cm, tray distance of 4 cm, particle size of 250-500 μm (mesh 60) without aeration, the maximum protein content of 25.82% were achieved, which were more than 80%, compared to the primary tomato pomace protein content (14.21% w w-1). This is the highest protein content already reported for tomato pomace, using the simplest technology at the lowest cost. Conflict of interest: The authors declare no conflict of interes

Optimization of 2,6-Dimethoxy Benzoquinone Production through Wheat Germ Fermentation by Saccharomyces cerevisiae

Background and objective: Nowadays, anticancer effects of 2,6 dimethoxy benzoquinone are verified. Optimization of 2,6 dimethoxy benzoquinone content of fermented wheat germ extract was carried out by investigating effects of the various effective factors on wheat germ fermentation by Saccharomyces cerevisiae. Material and methods: Effects of controlling concentration of dissolved oxygen in fermentation media were studied on 2,6 dimethoxy benzoquinone content of fermented wheat germ extract. To increase the quantity of 2,6 dimethoxy benzoquinone in fermented wheat germ extract, simultaneous effects of four effective variables including wheat germ particle size, agitation rate, dry materials to water ratio and yeast to wheat germ ratio at three levels were investigated using Taguchi statistical design. Then, effects of fermentation time and increased scale on the content of 2,6 dimethoxy benzoquinone of fermented wheat germ extract were assessed using bench-scale fermenter. Concentration 2,6 dimethoxy benzoquinone was assessed using HPLC. Molecular weight patterns of the fermented wheat germ extract proteins and total protein of fermented wheat germ extract were assessed using gel electrophoresis and Kjeldahl methods, respectively. Results and conclusion: Control of dissolved oxygen concentration of the fermentation process decreased 2,6 dimethoxy benzoquinone content to 0.135 mg g-1. Investigation effects of particle size of wheat germ, agitation rate, dry materials to water ratio and yeast to wheat germ ratio on 2,6 dimethoxy benzoquinone production showed that 2,6 dimethoxy benzoquinone concentration increased to 2.58 mg g-1 (dry material), one of the top concentrations ever reported. Effects of fermentation time in bench-scale bioreactor showed that the highest quantity of production was achieved within 16 h. Study of the protein patterns and total protein of fermented wheat germ extract and comparisons between these values and commercial samples showed that production improvement of 2,6 dimethoxy benzoquinone did not include significant effects on quality and quantity of proteins of fermented wheat germ extract. Results of this study demonstrated that fermentation conditions could significantly affect 2,6 dimethoxy benzoquinone contents of fermented wheat germ extract. Conflict of interest: The authors declare no conflict of interest

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Abstract This paper reviews recent strategies used for increasing specific yield and productivity in high cell density cultures. High cell density cultures offer an efficient means for the economical production of recombinant proteins. However, there are still some challenges associated with high cell density cultivation (HCDC) techniques. A variety of strategies in several aspects including host design consideration, tuning recombinant protein expression, medium composition, growth methodologies, and even control and analysis of the process have been successfully employed by biotechnologists to increase yield in high cell density cultures. Although most researches have focused on Escherichia coli, other microorganisms have the potential to be grown at high density and need further investigation. In recent years, information on physiological changes of hosts during different phases of cultivation derived from functional genomics, transcriptomics and proteomics is being used to overcome the obstacles encountered in high cell density cultivation and hence increase productivity