Batch growth kinetic studies of locally isolated cyanide-degrading Serratia marcescens strain AQ07

Abstract

The evaluation of degradation and growth kinetics of strain AQ07 was carried out using three half-order models at all the initial concentrations of cyanide with the values of regression exceeding 0.97. The presence of varying cyanide concentrations reveals that the growth and degradation of bacteria were affected by the increase in cyanide concentration with a total halt at 700 ppm KCN after 72 h incubation. In this study, specific growth and degradation rates were found to trail the substrate inhibition kinetics. These two rates fitted well to the kinetic models of Teissier, Luong, Aiba and Heldane, while the performance of Monod model was found to be unsatisfactory. These models were used to clarify the substrate inhibition on the bacteria growth. The analyses of these models have shown that Luong model has fitted the experimental data with the highest coefficient of determination () value of 0.9794 and 0.9582 with the lowest root mean square error (RMSE) value of 0.000204 and 0.001, respectively, for the specific rate of degradation and growth. It is the only model that illustrates the maximum substrate concentration () of 713.4 and empirical constant () of 1.516. Tessier and Aiba fitted the experimental data with a value of 0.8002 and 0.7661 with low RMSE of 0.0006, respectively, for specific biodegradation rate, while having a value of 0.9 and RMSE of 0.001, respectively, for specific growth rate. Haldane has the lowest value of 0.67 and 0.78 for specific biodegradation and growth rate with RMSE of 0.0006 and 0.002, respectively. This indicates the level of the bacteria stability in varying concentrations of cyanide and the maximum cyanide concentration it can tolerate within a specific time period. The biokinetic constant predicted from this model demonstrates a good ability of the locally isolated bacteria in cyanide remediation in industrial effluents.

Biosurfactant Production and Growth Kinetics Studies of the Waste Canola Oil-Degrading Bacterium Rhodococcus erythropolis AQ5-07 from Antarctica

“…The bacterium was cultivated under optimum conditions for canola oil degradation in nutrient broth (to an OD 600 of 1.3–1.4) [ 19 ] on an incubator shaker at 10 °C and 150 rpm for 84 h. About 10% ( v/v ) of the seed cultures were transferred to 100 mL of canola oil liquid medium containing initial canola oil concentrations ranging from 1%–7%. Following 12 h incubation under the same conditions, 1 mL aliquots from the culture medium were collected at 12 h intervals until 84 h and cell growth and canola oil degradation were measured [ 53 ]. The determination of the canola oil degradation kinetic variables was not possible because of the liquid nature of the oil.…”

Growth and Extracellular Enzyme Activity Responses of a Multi-enzymic Strain of Serratia sp. in a Simulated Diesel-contaminated System

“…This is similar to optical density measure which does not discriminate between live and dead cells in its ability to obstruct transmission and/or absorption of light through a defined path length. The ideal thing to have done would be to simply measure bacterial growth with optical density [20], toxicity studies such as this, viable are more expressive of bacterial responses than cell dry weight [21] because only live cells respond to toxicant onslaught.…”

“…This is similar to optical density measure which does not discriminate ad cells in its ability to obstruct transmission and/or absorption of light through a defined path length. The ideal thing to have done would be to simply measure bacterial [20], however, in toxicity studies such as this, viable counts data are more expressive of bacterial responses than because only live cells suggesting that respective variations in growth and death was substrate concentrationdependent. Since survivability of bacteria was critical to successful natural attenuation of the ecosystem, we measured diesel toxicity to the bacterium using the concentrations that supported growth since this concentration of TPH was observed in the ecosystem where the bacterium was isolated (data not shown).…”

Co-metabolism kinetics and electrogenesis change during cyanide degradation in a microbial fuel cell

“…And the higher concentration of cyanide is, the lower growth rate and OD 600 will be. 33 The electricity voltage output obtained from the MFC using varying sodium cyanide is shown in Fig. 11.…”