Enhancement of mycelial growth and polysaccharide production in Ganoderma lucidum (the Chinese medicinal fungus, `Lingzhi') by the addition of ethanol
Methanol, ethanol, 1-propanol and 2-propanol, at 1.5% (v/v), enhanced the growth and polysaccharide production of Ganoderma lucidum. Ethanol was the most effective at 1.5% (v/v) for increasing the biomass production, however, the maximal polysaccharide concentration was produced with 2% (v/v) ethanol in the medium. There was no new polysaccharide component produced by the addition of ethanol.
[Effects of extracts of Chinese medicines on Ganoderma lucidum in submerged culture].
Effects of water and ethanol extracts of 10 Chinese medicines, such as Astragalus membranaceus, Coix lachryma-jobi, etc., on biomass and exopolysaccharide of Ganoderma lucidum were studied by submerged culture. The results showed: water extracts of all medicines can improve the culture of G. lucidum except of A. membranaceus, ethanol extracts of C. lachryma-jobi, Dioscorea opposita, Codonopsis pilosula, and Achyranthes bidentata( < 187.5g Medicine/L substrate) can also increase the biomass of G. lucidum, but the ethanol extracts of Angelica sinensis, Dendrobium nobile check the growth of G. lucidum. The production of exopolysa-ccharide can be improved by all the Chinese medicines and their dosage used in this experiment, Although A. sinensis, D. Nobile check the growth of G. lucidum, they could stimulate the secretion of exopolysaccharide in lower dosage. It is concluded that some Chinese medicines, such as C. lachryma-jobi, D. opposita, C. pilosula, etc. can be processed by the fermentation of G. lucidum, and bio-active compound can be produced by adding appropriate Chinese medicine in the substrate to culture G. lucidum.
The influence of glucose concentration on citric acid production and morphology of Aspergillus niger in batch and culture
Studies in conventional batch culture confirmed that initial glucose concentration in the fermentation medium affected both the rate of citric acid fermentation by Aspergillus niger and the morphology of the producer micro-organism. A series of fed-batch (glucostat) experiments, in which the concentration of glucose was kept constant whereas all other conditions were allowed to change, were used to eliminate the effects of decreasing sugar concentration found during conventional batch experiments. The level of glucose had a marked effect on production rates; the specific rate of citric acid formation increased with increasing initial glucose concentration (batch culture) or glucose levels (glucostat culture), and in both culture methods, the specific growth rate increased with decreasing glucose concentration for the first 48 h of fermentation. The reduction observed in the mean length of filaments at low glucose levels could be explained by increased branching frequency as a result of the increasing specific growth rate at the early stages of fermentation. The size of the mycelial clumps was reduced at low glucose levels and their shape was also affected as the ratio between the perimeter of the clump and the perimeter of its core increased as glucose concentration decreased. Very low glucose levels during fermentation in glucostat culture had a striking effect on the metabolism of the micro-organism because the specific production rate decreased in favor of the specific growth rate and the morphology changed with a doubling of the size of clumps and pellet formation. The main morphological observations in both batch and glucostat cultures seemed to be related to the growth rate, which is restricted by the glucose concentration, and, thus, indirectly related to the concentration of glucose in the fermentation media. The glucose levels in the medium were shown to lead to a significant noncatalysed entry into the mycelium, which accounted for the citric acid productivity and growth rate changes.