Evaluation of biomass

Online analysis and process control in recombinant protein production (review)

Online analysis and control is essential for efficient and reproducible bioprocesses. A key factor in real-time control is the ability to measure critical variables rapidly. Online in situ measurements are the preferred option and minimize the potential loss of sterility. The challenge is to provide sensors with a good lifespan that withstand harsh bioprocess conditions, remain stable for the duration of a process without the need for recalibration, and offer a suitable working range. In recent decades, many new techniques that promise to extend the possibilities of analysis and control, not only by providing new parameters for analysis, but also through the improvement of accepted, well practiced, measurements have arisen.

Influence of Imidazolium Ionic Liquids on Dehydrogenase Activity of Activated Sludge Microorganisms

Imidazolium salts are one of the most often used and investigated groups of ionic liquids (ILs). The research concerning their ecotoxicity comprised many test organisms representing different trophic levels; however, their impact on mixed cultures of microorganisms such as activated sludge has been hardly ever investigated. Thus, in this work, the effect of imidazolium ionic liquids on dehydrogenase activity of activated sludge was estimated. Three activated sludges of different properties and origin were tested. It occurred that 1-alkyl-3-methyl imidazolium bromides do not inhibit dehydrogenase activity of sludge, if the alkyl chain contains up to six carbon atoms. The values of IC50 for these ILs were above 100 mg l(-1). At the same time, the inhibitory effect on dehydrogenase activity of activated sludge increases with the increase in chain length of the alkyl substituent. The degree of inhibition of dehydrogenase activity of sludge microorganisms is dependent on activated sludge properties.

Measurement of the Growth of a Floc Forming Bacterium Pseudomonas putida CP1

Pseudomonas putida CP1 formed clumps of cells when grown on mono-chlorophenols but not on phenol or glucose. An increase in cell numbers for the organism grown on mono-chlorophenols was accompanied by a decrease in the dry weight. The change in shape of the bacterium from rod shape to coccus shape coupled with a reduction in cell size when the organism was grown under nutritional stress was found. This result together with cell aggregation affected the measurement of growth parameters in the system by conventional methods (optical density measurements, dry weight measurements and the plate count technique). Monitoring growth of Pseudomonas putida CP1 by a direct microscopic count technique was found to be more representative than conventional methods including optical density measurements, dry weight measurements and the plate count technique when grown on phenolics.

Estimation of viable biomass in aerobic biodegradation processes of organic fraction of municipal solid waste (MSW)

2-(p-Iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) dehydrogenase test and RNA assay were introduced to evaluate biomass in the processes of aerobic biodegradation of the organic fraction of municipal solid waste (MSW) in bioreactors. It was found that RNA quantification by KOH/UV method delivered reliable and repeatable results. Relative standard deviation (RSD) for INT test was significantly higher than for RNA assay and achieved values of 3-15%. Moreover, it occurred that the optimum temperature for the growth of autochthonic biomass, which takes part in the biodegradation process, was in the range from 25 to 37 degrees C.