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CULTURAL STUDIES ON THE ASPERGILLI, WITH SPECIAL REFERENCE TO LIPASE PRODUCTION OF STRAINS ISOLATED FROM STORED COPRA AND CACAO
Author(s) -
EYRE J. C.
Publication year - 1932
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1932.tb04328.x
Subject(s) - copra , biology , lipase , food science , aspergillus niger , penicillium , mucor , aspergillus , botany , horticulture , biochemistry , enzyme
SUMMARY1 ‐Thirteen strains of Aspergillus , including four of A. niger and two of A. flavus , one strain each of Mucor racemosus and Syncephalastrum cinereum and a blue‐green Penicillium are dealt with in this paper. They were isolated from stored products, mainly copra and cacao. Determinations were made of the lipolytic activity of the dried mould, the weight of dried mould produced and the lipolytic activity, titratable acidity, and p H. of the liquid Czapek medium in which the moulds were grown. The influence of an increase in temperature was also investigated. 2 Figures are given for the lipolytic activity for 2 weeks' growth and in the case of some species also for 4 and for 8 weeks' growth. All the strains were found to be lipolytically active both as regards the medium and as regards the dried mould. On a basis of 2 weeks' growth the strains of Aspergillus were divided into two distinct classes in relation to the amount of lipase found in the medium. In the case of the activity of the dried mould two classes were again found. With two exceptions the same moulds were found to be in the same class in both cases. 3 It was found that while the lipolytic activity of the dried mould and of the medium were materially the same at 2 weeks as at 4 weeks, determinations made at 8 weeks indicated an increase in the activity of the medium and a decrease in the activity of the dried mould coincident with a decrease in the weight of growth. It is therefore suggested that the increase in the activity of the medium is due to autolysis and probably also to an increased excretion of enzyme. 4 As it was found that the amount of lipase in a medium containing coconut oil as the source of carbon was much greater than in a sucrose medium it is concluded that the coconut oil stimulated the production of the enzyme. 5 In the case of the Aspergilli there was a definite correlation between the colour of the mould, the colour of the medium and the titrat‐able acidity of the medium. The lighter coloured forms produced least acid and most colour in the medium, while the dark forms produced most acid and least colour. On autolysis the depth of colour of the medium increased and the titratable acidity decreased. 6 Marked differences in the titratable acidity of the medium were found between the four strains.of A. niger. An mcrease of temperature had the effect of bringing about still more marked differences and in addition, differences in lipolytic activity. No qualitative differences were found. 7 A. niger (copra), A. flavus (light), A. tamarii and A. sydowi were grown on a coconut oil emulsion. The rates at which the different species clarified the emulsion were noted. A. niger and A. flavus clarified the emulsion in the shortest time. The addition of sucrose had the effect of considerably retarding the assimilation of the oil in the emulsion.