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Nadja Radchenkova Ivanka Boyadzhieva Merve Erginer Haskylü Nikolina Atanasova Songül Yaar Yldz Margarita J. Kuncheva Ivan Panchev Hristo Kisov Spasen Vassilev Ebru Toksoy Oner Margarita S. Kambourova 《Engineering in Life Science》2020,20(8):357-367
Unusual composition of an exopolymer (EP) from an obligate halophilic bacterium Chromohalobacter canadensis 28 has triggered an interest in development of an effective bioreactor process for its production. Its synthesis was investigated in 2‐L bioreactor at agitation speeds at interval 600‐1000 rpm, at a constant air flow rate of 0.5 vvm; aeration rates of 0.5, 1.0, and 1.5 vvm were tested at constant agitation rate of 900 rpm. EP production was affected by both, agitation and aeration. As a result twofold increase of EP yield was observed and additionally increased up to 3.08 mg/mL in a presence of surfactants. For effective scale‐up of bioreactors mass transfer parameters were estimated and lowest values of KLa obtained for the highest productivity fermentation was established. Emulsification activity of EP exceeded that of trade hydrocolloids xanthan, guar gum, and cellulose. A good synergism between EP and commercial cellulose proved its potential exploration as an enhancer of emulsifying properties of trade emulsions. A pronounced lipophilic effect of EP was established toward olive oil and liquid paraffin. Cultivation of human keratinocyte cells (HaCaT) with crude EP and purified γ‐polyglutamic acid (PGA) showed higher viability than control group. 相似文献
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Serafim Vlaev Sneghana Rusinova-Videva Konstantsa Pavlova Margarita Kuncheva Ivan Panchev Svoboda Dobreva 《Applied microbiology and biotechnology》2013,97(12):5303-5313
Production of biomass and extracellular polysaccharide (EPS) from psychrophilic Sporobolomyces salmonicolor AL1 in a stirred bioreactor was studied. The aspects of production technical-scale parameters, namely, bioreactor flow field, biomass and EPS production rates, oxygen mass transfer per input power, as well as important product properties, such as rheology and stability of EPS mixtures, were considered. The bioprocess was found to proceed in non-Newtonian flow with consistency coefficient rising typically to 0.03 Pa.sn and flow index declining to 0.7. Flow modeling was carried out and showed good homogenization for substrate delivery at agitation rates exceeding 400 rpm. Agitation rates lower than 400 rpm were considered counterproductive due to flow field non-uniformity. The cell density reached 5 g/l and EPS production yield reached 5.5 g/l at production rate 0.057 g EPS/l per hour (0.01 g EPS/g biomass per hour). Oxygen uptake rate and oxygen transfer rate were in the range of 0.5–1.7 mmolO2/l per hour and 2–4.7 mmolO2/l per hour, respectively. The mass transfer coefficient at reaction conditions was found to be in the range $ {K_L}a\tilde{\mkern6mu} 0.004-0.01{{\mathrm{s}}^{-1 }} $ . The bioprocess biological performance was higher at moderate agitation speed and revealed biomass diminution and cell inactivation by increasing impeller revolutions and shear rate. The product EPS was found to introduce shear-thinning behavior in water solutions with apparent viscosity of up to 30 mPa.s and to stabilize 1–2 % oil-in-water emulsions improving their lipophilic properties. The emulsion dispersion index was found to be comparable with the one of Arlacel 165, the emulsifier used in cosmetic. The long-term performance of the complex cream mixtures of the glucomannan prepared in commercial format was found promising for further application. 相似文献
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Extracellular polymer substance synthesized by a halophilic bacterium Chromohalobacter canadensis 28
Radchenkova Nadja Boyadzhieva Ivanka Atanasova Nikolina Poli Annarita Finore Ilaria Di Donato Paola Nicolaus Barbara Panchev Ivan Kuncheva Margarita Kambourova Margarita 《Applied microbiology and biotechnology》2018,102(11):4937-4949
Applied Microbiology and Biotechnology - Halophilic microorganisms are producers of a lot of new compounds whose properties suggest promising perspectives for their biotechnological exploration.... 相似文献
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