Interrelation of growth media and water activity in sclerotia characteristics of Aspergillus section Flavi (original) (raw)
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Effects of environmental factors on growth and sclerotium formation in Aspergillus ochraceus
Canadian Journal of Botany, 1980
The effects of carbohydrates, amino acids, sulphur-containing compounds, temperature, pH, and light on growth and sclerotium production in Aspergillus ochraceus were studied. The maximal number of sclerotia was formed on medium containing sucrose at a concentration of 2 × 10−1 M, while on the lactose, galactose, and arabinose media no sclerotia were formed and poor mycelial growth was observed. Among the amino acids tested, glutamic acid (10−2 M) enhanced sclerotium formation, whereas there was complete inhibition when methionine (10−2 M) and ethionine (10−2 M) were added. Good production of sclerotia occurred on medium containing glutathione in all concentrations tested. Among the other sulphur-containing compounds tested, only sodium thiosulphate at a concentration of 10−1 M inhibited sclerotium formation without inhibition of mycelial growth. The pH at which sclerotia were formed ranged from 4.0 to 9.0. There was no growth at pH 3.0, and normal mycelial growth without sclerotium ...
Enzyme and Microbial Technology, 2004
The effect of interactions of water activity (a w ) (0.99-0.90), temperature (20, 30 and 35°C) and modifying aw solute (glycerol, NaCl) on growth and sporulation of a wild type strain of Aspergillus niger (W) and two genetically engineered lysozyme producing strains (L11, B1) was examined for the first time. Maximum growth rates were achieved for both strains (L11 and B1) under moderate a W levels. L11 showed a higher growth rate than B1. Fastest growth was achieved at 30 o C, using glycerol as solute. Optimum conditions for growth of strain L11
Studies on the Sclerotia of Some Species in The Genus Aspergillus
Egyptian Journal of Botany, 2017
T HIS study is part of a large study concerning with the sclerotia of some species of genus Aspergillus. In the present study, the sclerotia of different aspergilli (Aspergillus sclerotioniger, A. sclerotiorum, A. candidus, A. flavus, A. piperis, A. ochraceus, A. robustus, A. sepultus, A. petrakii, A. melleus, A. parasiticus and A. sclerotiicarbonarius) were examined concerning their morphological and anatomical characters. The mature sclerotia in the cultures of the used aspergilli appeared with different shapes (globose, sub-globose and oval). Transverse sections of mature sclerotia revealed two regions; the outer region, considered as rind, while the inner region proposed as medulla. These aspergilli were tested also by polymerase chain reaction (PCR) technique for the presence of sclerotium regulator (SclR) gene. The results indicated that eight of them contain this gene; these were A. petrakii, A. sepultus, A. robustus, A. sclerotiicarbonarius, A. melleus, A. sclerotioniger, A. parasiticus and A. sclerotiorum. These species exhibited bands with different molecular weights when tested for presence of SclR gene. Each Aspergillus species showed one band with specific molecular weight, these bands ranged in size; the highest was 436 bp (A. parasiticus) while the lowest was 134 bp (A. sclerotiicarbonarius).
International Journal of Food Microbiology, 2010
The effects of water activity (a w ) of diverse media i/ culture medium for sporogenesis, a w sp ii/ liquid spore suspension medium, a w su and iii/ medium for germination, a w ge , on the germination time t G of Aspergillus carbonarius, Aspergillus flavus, Penicillium chrysogenum and Penicillium expansum were assessed according to a screening matrix at 0.95 and 0.99 a w . It was shown that i/ reduced t G s were obtained at 0.95 a w sp except for P. expansum ii/ a significant effect of a w su on t G was demonstrated for A. carbonarius, P. chrysogenum and P. expansum iii/ the most important factor for controlling the germination time was the medium for germination except for A. carbonarius (a w su ). In accordance with the fact that fungal spores can swell as soon as they are suspended in an aqueous solution it is recommended to re-suspend fungal spores in a solution at the same water activity as that of subsequent germination studies.