Nor Zalina Othman

Efficient production process for food grade acetic acid by acetobacter aceti in shake flask and in bioreactor cultures

Acetic acid is one of the important weak acids which had long history in chemical industries. This weak organic acid has been widely used as one of the key intermediate for many chemical, detergent, wood and food industries. The production of this acid is mainly carried out using submerged fermentation system and the standard strain Acetobacter aceti. In the present work, six different media were chosen from the literatures and tested for acetic acid production. The highest acetic acid production was produced in medium composed of glucose, yeast extract and peptone. The composition of this medium was optimized by changing the concentration of medium components. The optimized medium was composed of (g/L): glucose, 100; yeast extract, 12 and peptone 5 and yielded 53 g/L acetic acid in shake flask after 144 h fermentation. Further optimization in the production process was achieved by transferring the process to semi-industrial scale 16-L stirred tank bioreactor and cultivation under controlled pH condition. Under fully aerobic conditions, the production of acetic acid reached maximal concentration of about 76 g/L and 51 g/L for uncontrolled and controlled pH cultures, respectively.

Anaerobic Probiotics: The Key Microbes for Human Health

Human gastrointestinal microbiota (HGIM) incorporate a large number of microbes from different species. Anaerobic bacteria are the dominant organisms in this microbial consortium and play a crucial role in human health. In addition to their functional role as the main source of many essential metabolites for human health, they are considered as biotherapeutic agents in the regulation of different human metabolites. They are also important in the prevention and in the treatment of different physical and mental diseases. Bifidobacteria are the dominant anaerobic bacteria in HGIM and are widely used in the development of probiotic products for infants, children and adults. To develop bifidobacteria-based bioproducts, therefore, it is necessary to develop a large-scale biomass production platform based on a good understanding of the ideal medium and bioprocessing parameters for their growth and viability. In addition, high cell viability should be maintained during downstream processing and storage of probiotic cell powder or the final formulated product. In this work we review the latest information about the biology, therapeutic activities, cultivation and industrial production of bifidobacteria.

Production of α-amylase using new strain of Bacillus polymyxa isolated from sweet potato

In this study, a new amylase producer strain was isolated from sweet potato tuber. This strain was able to grow at 37 °C and produce α-amylase in high quantity compared to other standard strain cultures. In the first part, cultivation in shake flask in standard medium was carried out to give complete information about the growth and production kinetics of this strain. The results clearly demonstrate that the isolated strain is able to production α-amylase in submerged culture with concentration up to 2050 kat/L after 20 h cultivation. Furthermore, medium optimization was carried out by changing the starch concentration and cell cultivation in medium of mixed carbon source (composed of starch and glucose of ratio 15:5 g/g) to enhance the production process and to increase the growth rate. The volumetric and specific α-amylase production in this optimized medium were 4550 kat/L and 1060 kat/g, respectively. Further improvement in enzyme production process was achieved by scaling up the process from shake flask to 3-L stirred tank bioreactor under non-oxygen limiting condition. The maximal volumetric and specific α-amylase productions in bioreactor batch culture were 5210 kat/L and 1095kat/g, respectively, after only 14 h cultivation. Keywords - α-amylase, Bacillus polymyxus, bioprocess optimization, batch cultivation

Bioprocess development for kefiran production by Lactobacillus kefiranofaciens in semi industrial scale bioreactor

Lactobacillus kefiranofaciens is non-pathogenic gram positive bacteria isolated from kefir grains and able to produce extracellular exopolysaccharides named kefiran. This polysaccharide contains approximately equal amounts of glucose and galactose. Kefiran has wide applications in pharmaceutical industries. Therefore, an approach has been extensively studied to increase kefiran production for pharmaceutical application in industrial scale. The present work aims to maximize kefiran production through the optimization of medium composition and production in semi industrial scale bioreactor. The composition of the optimal medium for kefiran production contained sucrose, yeast extract and K2HPO4 at 20.0, 6.0, 0.25 g L−1, respectively. The optimized medium significantly increased both cell growth and kefiran production by about 170.56% and 58.02%, respectively, in comparison with the unoptimized medium. Furthermore, the kinetics of cell growth and kefiran production in batch culture of L. kefiranofaciens was investigated under un-controlled pH conditions in 16-L scale bioreactor. The maximal cell mass in bioreactor culture reached 2.76 g L−1 concomitant with kefiran production of 1.91 g L−1.

Improvement of cell mass production of Lactobacillus delbrueckii sp bulgaricus WICC-B-02: A newly isolated probiotic strain from mother’s milk -

Lactobacillus delbrueckii sp bulgaricus WICC-B-02 is new probiotic strain which was initially isolated from the mother’s milk. As lactic acid bacterium, it’s known as a highly efficient probiotic microorganism with a wide range of benefits on the human health. This study was conducted to design and establish industrial platform for high cell mass production of L. delbrueckii sp bulgaricus for pharmaceutical and food industries application. However, due to low cell mass production caused by the accumulation of lactic acid during the cultivation of lactic acid bacteria, therefore, the optimization of cell mass production with low lactic acid production was developed in this study. The new formulation of the production medium was developed by optimizing the main components such as glucose (30 g.L-1), yeast extract (6.0 g.L-1) and peptone (6.0 g.L-1) in shake flask cultivation. The cell mass production was 3.14 g.L-1, and it increased to 6.08 g.L-1 with the lactic acid production being reduced by about 33%, compared to the un-optimized medium.

Microbial Xylanases: Sources, Types, and Their Applications

Biomass conversion to an utilizable energy sources such as monomer sugars using enzymatic hydrolysis has been emerged as the current technology which promises the future energy. In nature, bioconversion process of biomass is mediated by a group of biofunctional hydrolytic enzymes. These enzymes generally work in cooperative synergetic action to facilitate enhanced effective degradation of biomass. Xylanase is one of the crucial hydrolytic enzymes involved in hydrolysis of xylan, the hemicellulose which constitutes 15–30 % of the plant biomass. This chapter discusses in detail about the enzymatic hydrolysis of xylan by the xylolytic enzyme endo-1,4-β-xylanase, its occurrence in nature and mode of action, structure and classifications, current methods for its production, purification, and characterization. In addition, the major and recent industrial applications of this enzyme were highlighted as well.

Glucose concentration affects recombinant interferon α-2b production in Escherichia coli using thermo-induction system

In the present work, a recombinant Escherichia coli strain was used for the production of interferon α-2b in both shake flask and bioreactor. The first part of this research focused on the investigation of the effect of glucose concentration on the kinetics of cell growth, recombinant protein production and acetate formation. Glucose supplementation to culture medium enhanced cell growth when added in concentration between 0-20 g/L. Further increase in glucose level reduces biomass production and enhances acetate accumulation in culture. On the other hand, the results clearly demonstrated that maximal interferon production of 27.7 mg/L was achieved in culture supplemented with 20 g/L glucose. Further improvement in recombinant protein production process was also achieved by scaling up from shake flask to 16-L stirred tank bioreactor using pH-stat cultivation strategy. The maximal volumetric interferon production in bioreactor batch culture was 44.5. mg/L after only 6 hours.

Medical and Cosmetic Applications of Fungal Nanotechnology: Production, Characterization, and Bioactivity

Nowadays, nanotechnology is widely applied for the development of highly efficient products in the pharmaceutical and cosmetic industries. Converting bioactive materials to nanoscale not only increases their biocompatibility but also increases their effectiveness, even when lower doses are used. Metal nanoparticles can be synthesized by fungal cells both intra- and extracellularly. Stabilization of the physical and chemical properties of various noble metal nanoparticles produced by fungi can be achieved through controlling the size, surface morphology, and surface chemistry of the nanoparticles. Intracellular synthesis provides smaller nanoparticles with well defined dimensions, but contributes to difficulty in downstream processing activity as compared with synthesis by extracellular methods. Recently, the production of nanoparticles from fungi has received extensive attention, owing to the capacity of fungi to produce nanoparticles extracellularly, a process that is more reliable and ecofriendly than intracellular methods, with relatively simple downstream processing. Fungi secrete extracellular enzymes for their survival and they control metal cation transportation to maintain intracellular homeostasis; when more protein is excreted nanoparticle synthesis is increased. To maximize nanoparticle synthesis, the rate of their synthesis can be increased through optimization of the total fungal cell mass and bioprocessing parameters, such as time of exposure, temperature, and pH. This will facilitate increased productivity in the fungal synthesis of nanoparticles for applications in the pharmaceutical and cosmetic industries.