this paper investigates the importance of considering biomass growth and decay for predicting a field scale microbial degradation of btex plume in an unconfined aquifer system in the pump station area of tehran oil refinery (tor), iran. a two-dimensional finite volume model has been presented to predict multi-species reactive transport incorporating physical, chemical and biological processes i...

background and objectives: proteases are a group of enzymes that catalyze the degradation of proteins resulting in the pro- duction of their amino acid constituents. they are the most important group of industrial enzymes which account for about 60% of total enzymes in the market and produced mainly by microorganisms. the attempts were made to study the kinetic parameters of protease produced b...

the batch fermentation production of human growth hormone (hgh) was studied in a newrecombinant escherichia coli. the effect of different levels of dissolved oxygen and glucoseconcentration on cell density and substrate utilization were evaluated. the results indicated that theoptimum level of dissolved oxygen was 25% of air saturation. the specific growth rate reached amaximum for an optimal g...

The study focused on variable kinetics for substrate utilization, primarily addressing the following issue: Is variable process kinetics observed under different operating conditions and culture history (sludge ages), the result of changes inflicted on the metabolic machinery of the same microbial culture? Or, is this the result of a different microbial population selected under different opera...

The nature of non-exponential kinetics in microbial cells inactivation by pulsed electric fields (PEF) is discussed. It was demonstrated that possible mechanism of non-exponential kinetics can be related to orientational disorder in suspension of microbial cells of anisotropic form. A numerical studies of spheroidal cell suspensions was carried out. The most pronounced deviations from the expon...

Three ethanol extracts, chamomile (CHA), clove (CLO) and tarragon (TAR), were tested at five doses (0, 250, 500, 750 and 1000 µL/L) to determine their effects on in vitro organic matter digestibility (IVOMD), metabolizable energy (ME), net energy of lactation (NEL), short-chain fatty acids (SCFA), microbial mass (MM) and rumen fermentation kinetics of a 40:60 forage: concentrate diet using in v...

Predictive microbial models generally rely on the growth of bacteria in laboratory broth to approximate the microbial growth kinetics expected to take place in actual foods under identical environmental conditions. Sigmoidal functions such as the Gompertz or logistics equation accurately model the typical microbial growth curve from the lag to the stationary phase and provide the mathematical b...

Microbial spoilage is one of the main factors affecting the quality of fresh fruits and vegetables, leading to off-flavor, fermented aroma, and tissue decay. The knowledge of microbial growth kinetics is essential for estimating a correct risk assessment associated with consuming raw vegetables and better managing the development of spoilage microorganisms. This study shows, for the first time,...