The extent of breakdown of fructose and glucose derived from sucrose in the medium of Murashige and Skoog (1962) during autoclaving was investigated by polarographic measurement. Although not present in the original MS medium but often used in place of FeSO4 + Na2-EDTA, FeNa-EDTA was found to be primarily responsible for catalyzing the breakdown of these monosaccharides. It would therefore be good practice to autoclave FeNa-EDTA separate from the carbohydrate constituents of the medium in order to reduce the formation of toxic substances derived from the latter's breakdown. Autoclaving FeNa-EDTA separately has the additional advantage of preventing precipitation of certain micronutrient elements. Further precipitation can be avoided by autoclaving FeNa-EDTA and KH2PO4 together, but separately, from other components of the medium. By eliminating precipitation and minimizing the breakdown of monosaccharides during autoclaving, it is possible to improve the quality of the medium without resorting to sterilization by filtering.
1982. Aspects of photoinduction of carotenogenesis in the fungus VerticiUium agaricinum. -Physiol. Ptant. 54: 235-238.An action spectrum for light induced carotenogenesis in VerticiUium agaricinum (Link) Corda (ATCC 24668) was obtained by exposing mycelial pads to monochromatic radiation. Action maxima occurred at 290 (main peak) and 390 nm, and there was a minor peak at 483 nm. The results also showed interaction helween the blue and UV light. Bine light partly reversed the UV light induction of carotenogenesis when given after, but not when given before UV light. This implies that there are at least two photoreeeptors involved in carotenogenesis in VerticiUium, but phytochrome is not likely to be one of them.Additional key-words -Action spectrum, blue ight, UV light.
As the autoclaving of a sugar together with other nutrient components enhances its degradation with the associated formation of toxic products, it is advisable to autoclave it separately from other medium components. In such cases, and to prepare growth media of consistent quality, it may also be necessary to adjust the duration of autoclaving according to the volume of the sugar solution. The results of an attempt to fine‐adjust the autoclaving procedure are presented.
Glucose, used as model sugar in this investigation, was autoclaved for 20,32 or 44 min in volumes of 0.25. 1.2 and 5 1. The rise in temperature of the solutions was monitored by thermocouples. Glucose degradation was estimated by the rate of cyanide‐initiated oxygen consumption. The rates were found to be inversely proportional to the volumes in a semilogarithmic plot. The T‐t (temperature‐time) value, the area under the solution temperature vs time curve, was found to be an independent variable from which the extent of glucose degradation could be deduced. For a chosen level of thermodegradation of glucose, the duration of autoclaving for solutions of different volumes could be determined graphically from a T‐t value vs time plot.
1995. Sugar degradation during autoclaving: Effects of duration and solution volume on breakdown of glucose. -Physiol. Plant. 94: 415^18.As the autoclaving of a sugar together with other nutrient components enhances its degradation with the associated formation of toxic products, it is advisable to autoclave it separately from other medium components. In such cases, and to prepare growth media of consistent quality, it may also be necessary to adjust the duration of autoclaving according to the volume of the sugar solution. The results of an attempt to fine-adjus! the autoclaving procedure are presented. Glucose, used as model .sugar in this investigation, was autoclaved for 20,32 or 44 min in volumes of 0.25. 1,2 and 5 1. The rise in temperature of the solutions was monitored by thermocouples. Glucose degradation was estimated by the rate of cyanide-initiated oxygen consumption. The rates were found to be inversely proportional to the volumes in a semilogarithmic plot. The T-t (temperature-time) value, the area under the solution temperature vs time curve, was found to be an independent variable from which the extent of glucose degradation could be deduced. For a chosen level of thermodegradation of glucose, the duration of autoclaving for solutions of different volumes could be determined graphically from a T-t value vs time plot.
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