STUDIES ON GLUTAMIC ACID PRODUCTION BY BACILLUS ISOLATES INVOLVED IN 'DADDAWA' FERMENTATION
STUDIES ON GLUTAMIC ACID PRODUCTION BY BACILLUS ISOLATES INVOLVED IN 'DADDAWA' FERMENTATION
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Date
1988-11
Authors
OGBADU, JUMEYI LUCY
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Abstract
The fermentation of African locust bean (Parkia
biglobosa) and soya bean (Glycine max) seeds for daddawa
production are carried out by Bacillus species. The species
which appeared to be responsible for the fermentation of
locust bean seeds were found to be variable. In six
separate fermentations, B._ subtilis, B. pumilus and B.
licheniformis were identified. Bacillus subtilis
predominated in four of the six fermentations. In soya bean
fermentation, on the other hand, B._ subtilis and B._ pumilus
were consistently isolated in all the three fermentations
examined. The growth of the B._ subtilis was favoured by low
oxygen tension. A rise in pH and temperature were observed
in the fermentations of both African locust bean and soya
bean.
A comparative analysis of glutamic acid contents of
both locust bean and soya bean daddawa showed higher value
in the latter. Release and increase in glutamic acid in
fermenting locust bean daddawa by B. subtilis- DU2 was
observed to correspond with the trend of glutamic acid
synthesis by the same isolate in a basal medium.
A total of twenty-five Bacillus strains comprising of
eight species were isolated from five Nigerian fermented
vegetable proteins and fermenting daddawa. The Bacillus
isolates were screened for glutamic acid producing ability
in the basal medium. They were all found to produce
glutamic acid in varying concentrations and are thus
confirmed to contribute to levels of glutamic acid in the
fermented vegetable proteins.
Bacillus subtilis - DU2 involved in daddawa
fermentation was selected for studies in which the effects
of various nutrients and growth parameters on glutamic acid
production were investigated. It was observed that glucose,
sucrose, galactose and fructose, all of which are found in
locust bean seeds supported high yields of glutamic acid.
Some intermediates of the Kreb's cycle namely succinate and
citrate supported yields of glutamic acid which were
generally lower than those of the sugars. Biotin was
essential for glutamic acid production and the optimal
concentration was 4-6ug/l. Among the metal ions
investigated, manganese and magnesium were the best while
zinc was the least in supporting glutamic acid synthesis.
Cobalt was found inhibitory to both growth and glutamic acid
production of the isolate. The best pH and temperature
range for optimum glutamic acid production were 7.5 and 3 5°C
respectively. Urea, ammonium chloride and ammonium sulphate
were found to support good glutamic acid production as
nitrogen sources.
When the basal medium was supplemented with different
flours of leguminous seeds, there were no appreciable
difference in the yield of glutamic acid over that of basal
medium alone. Glutamic acid yield was highest in the soya
bean supplemented medium followed by medium supplemented
with locust bean, cowpea, peanuts and bambara nuts.
The surface active agents, tween-80 and triton-X were
incorporated into the media at the beginning and at 66th
hour of the fermentation. Both surfactants caused increased
glutamic acid yields by the organism and in about equal
concentrations for optimal yields. Addition of the
surfactants at the beginning of the fermentation had a more
enhancing effect on glutamic acid release than their
addition at 66th hour. Viability of the fermenting
organisim did not appear to be affected at the
concentrations of the surfactants used.
Exposure of the wild B._ subtilis - DU2 to ultraviolet
light and X-ray resulted in producing some strains which at
32°C produced levels of glutamic acid comparable with that
of the wild strain but at 40°C, they (mutants) produced
higher levels of the amino acid. There was no appreciable
observable influence on the wild isolate exposed to acridine
orange in glutamic acid synthesis.
Description
A DISSERTATION
BY
LUCY JUMEYI OGBADU
SUBMITTED TO THE POST GRADUATE SCHOOL
AHMADU BELLO UNIVERSITY, ZARIA.
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR
THE DEGREE OF DOCTOR OF PHILOSOPHY
Keywords
STUDIES, GLUTAMIC, PRODUCTION, BACILLUS, ISOLATES, INVOLVED, DADDAWA', FERMENTATION.