Cultivation-time studies

The vast identification potential of micro-Raman spectroscopy combined with the aforementioned sophisticated chemometric analysis methods is corroborated within various works In one study a total of 2257 Raman spectra of single cells were used to differentiate among 20 strains belonging to 9 different species. Here, a recognition rate of 89.2% for strains using the SVM technique could be achieved, albeit these bacteria were grown under different conditions (cultivation time medium, and temperature). [45]... 

Physiology of immobilised C. fusiformis during long-term semicontinuous cultivation was studied by Kfen et al. (1987b). The immobilised cells maintained the alkaloid production for 770 days. The cells underwent profound morphological changes—vacuolisation, mitochondrial degeneration. The beads remained mechanically stable for the whole time. 

Additional information on essential oil variation in C. monspeliensis comes from a study by Angelopoulou et al. (2002) who were interested in diurnal and seasonal patterns. Significant differences were noted during both time periods. It would be of interest to learn what effects cultivation in a common garden enviromnent would have on oil expression in these species. 

A medium of Linsmayer Skoog (8) supplemented with 0.2 mg/L 2.4-dichlorophenoxyacetic acid as a growth regulator was used for the growth of cell suspension The cultivation was carried out in Erlenmayer flasks with 1/5 net volume on a shaker (11.6 rad/s) in the dark, at 26 - 28°C. In compliance with the nature of the experiment, flasks of different size were used 100 - 1000 cm, and the duration of the cultivation was 5 days for growing the inoculum and 12 days for studying the time course of growth. 

The soil was collected from the Mezquital Valley, located near Pachuca in the State of Hidalgo (Mexico). The irrigation water used was slightly alkaline with a pH of 8.4. The experiment was carried out under greenhouse conditions. Soil collected from three sub sites was placed into cylindrical pots. Five treatments were established in order to study the effect of wastewater and urea on the cultivation of maize (Zen mays L.). The treatments were a) SMWW, maize plant plus wastewater b) SMUREA, maize plant plus urea as fertilizer c) SUREA, uncultivated soil and urea as fertilizer d) SWW, uncultivated soil plus wastewater and e) SCONTROL treatment, soil plus tap water. Soils from the SMWW and SWW treatments were irrigated with 1000 mL of wastewater every 7 days from the first day onwards, making a total of 13 times overall. This means that a total amount of mineral N equivalent to 120 kg N ha-1 was added to each maize plant, i.e. the recommended amount of N fertilizer for maize. 

The last paper in this category describes monitoring of a submerged filamentous bacterial cultivation.38 Arnold et al. studied a 12-1 stirred tank where a strain of Streptomyces fradiae was used for fermentation. They followed ammonium, methyl oleate, glucose, and glutamate concentrations over time in the production of tylosin. 

R. rubrum was shown to possess hydrogenase and its activity was followed for 72 h. The bacteria were grown synchronously under anoxic conditions, with N2 or CO2 gas, at 30°C and in absence or presence of SeO . The production of dimethyl selenide and dimethyl diselenide was detected by chemiluminescence detection of samples of the gas phase (Fig. 9.12). After a 24 h exposure to complete darkness, the bacteria were transferred to the experimental conditions and changes in the activity of hydrogenase with time were studied in non-growing cells, cultivated in white light. 

The bioassay technique was developed to reduce the uncertainties associated with the use of native vegetation or cultivated crops. Plants can be started under controlled conditions and exposed under standardized conditions. Species and cultivars can be selected for oxidant sensitivity and symptom characteristics. The two studies just noted were the most closely controlled. Similar work has not been repeated. However, many investigators have grown plants under known cultural conditions and then transplanted them to field sites where they received special care. These plants can then be read for foliar symptoms throughout a given period, and the symptoms related to oxidant concentrations. The lack of apparent correlation in the two early studies could be due to the lack of specificity for the monitored oxidants, the presence of different concentrations of interacting oxidants at different times, or variations in cultural conditions between exposure times. 

In order to quantify the physical environment of a bioreactor, fluorescence assays can be applied for on-line monitoring of the mixing time behavior of all types of bioreactors. In this case the fluorosensor probe can be installed in the bioreactor at different locations of interest. Afterwards, selected fluorophores can be injected in order to study the overall mixing time. These fluorophores must fit to the excitation and emission behavior of the probe and should be selected in regard to the pH-dependency of the bioprocess, and when used during cell cultivation experiments they should not interfere with the cells. Scheper and Schiigerl reported on the use of different coumarins for mixing time experiments under bioprocess relevant conditions [49]. 

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