GLUCOSE ISOMERASE (Streptomyces violaceoniger)
Explanation
This enzyme preparation has not previously been reviewed by the
Joint FAO/WHO Expert Committee on Food Additives.
The enzyme preparation consists of whole cells of
S. violaceoniger plus filter acids. The strain is reference number
CBS 409-37 (Centraal Bureau voor Schimmelcultures). The organism is
grown in a medium containing corn steep liquor, carbohydrate material
containing xylose (corn cob), MgSO4 (1 g/l) and CoCl2 (0.01 g/l).
The mycelial mass plus filtration acid (Fuller's earth) is separated
from the fermentation mixture or a rotary vacuum filter, and flash
dried.
The following streptomyces species are thought to be identical
to S. violaceoniger: antimycoticus, chitaensis, endus,
hygroscopicus jenssen, naganishu, nigrescens, noboritaensis,
platensis, rutgersensis, tubercidicus, vastatus.
Although many forms of S. violaceoniger produce antibiotics
under certain conditions, no antibiotic was detected in concentrated
mycelia or the incubation medium of S. violaceoniger CBS 409-73
produced under industrial conditions. The level of sensitivity was
equivalent to 2-5 µg/ml of neomycin.
In use, the enzyme is added to glucose syrup in a concentration
of 8 g/l, and is recovered by filtration.
BIOLOGICAL DATA
TOXICOLOGICAL STUDIES
Acute toxicity and pathogenicity
A culture of S. violaceoniger CBS 409-73 was prepared in broth
(5% dextrose). The filtrate was injected intravenously into 10 mice in
a dose of 0.2 ml per mouse. The culture suspension was injected
intraperitoneally into 10 mice in a dose of 0.5 ml per mouse. The
corresponding control mice were given non-inoculated medium. No
mortality or behavioural abnormalities occurred over a 2-week period.
Short-term studies
Rat
Six groups each containing 10 male and 10 female Sprague-Dawley
rats were assigned to the following treatments: I, normal feed and
water; II, normal feed and 13.5% invert syrup (10% invert sugar in
water); III, feed containing 5% used S. violaceoniger (lysed) and
13.5% invert syrup prepared with S. violaceoniger and unrefined; IV,
normal feed plus 13.5% invert syrup prepared with S. violaceoniger
and unrefined; V, feed containing 5% fresh S. violaceoniger (lysed)
plus water; VI, feed containing 5% used S. violaceoniger (lysed)
plus water. The protocol may be summarized thus:
I II III IV V VI
Feed X X X
+ used S.v. (5%) X X
+ fresh S.v. (5%) X
Water X X X
+ invert syrup X
+ S.v. invert syrup X X
Body weight and consumption of feed and water was recorded each
week. The feeding trial continued for 4 weeks, then haematology, blood
biochemistry, urine analysis, organ weight and histological
examinations were made. Food consumption was below control values in
rats drinking invert sugar solutions (Groups I, III and IV), in whom
sugar intake exceeded 20 g/kg daily; these rats were hyperglycaemic.
Weight gain was normal in all groups. There were no significant
deviations from normal in erythrocyte and leucocyte cell counts,
haemoglobin, haematocrit, differential leucocyte count, BUN, serum
total protein, bilirubin, cholesterol, Na+, K+, Cl-, Ca2+,
phosphate, alkaline phosphatase, SGOT, SGPT, urine analyses for
glucose, proteins, ketone bodies, bilirubin or blood. Hydronephrosis
was noted unilaterally in one male rat in Group II and in one in Group
III and bilaterally in one male rat in Group IV. Liver weights were
raised in Groups II, III and IV. Relative weights of thyroid, heart,
spleen, kidneys, adrenals and gonads were all within normal ranges.
Histological examination of heart, stomach, jejunum, colon, liver,
pancreas, kidneys, spleen, adrenals, thyroid, testes and ovaries
revealed no abnormalities related to treatment with S. violaceoniger
(IFREB No. 741008).
A 90-day study with 4 groups each containing 10 male and 10
female Sprague-Dawley rats was carried out with a high-protein feed
and 10% invert sugar from different sources instead of drinking-water.
The groups were as follows: I, control invert sugar; II, glucose
isomerized with S. violaceoniger and refined; III, as II, but not
refined; IV, as III plus 2.5% S. violaceoniger. There were no
abnormalities in growth rates, feed and drink consumption,
haematology, serum biochemistry, urine analysis or organ weights
(observations as specified above for a 4-week study). Histological
examination of aorta, heart, stomach (rumen and fundus), pylorus,
liver (including special stains, pancreas, spleen, mesenteric nodes,
kidneys, prostate, thyroid, adrenals, gonads and uterus revealed only
commonly occurring lesions with no clustering within any of the
treatment groups (IFREB No. 751013).
Comments
No toxicologically significant effects were produced in rats by
Streptomyces violaceoniger preparations in feed or drink in 2 well-
designed and thorough short-term studies. However, information is
required about the occurrence in nature of the microorganism from
which the enzyme is obtained.
EVALUATION
Estimate of temporary acceptable daily intake for man
Not specified.*
FURTHER WORK OR INFORMATION
Required by 1984.
Information about the occurrence of Streptomyces violaceoniger
in nature.
* The statement "ADI not specified" means that, on the basis of the
available data (toxicological, biochemical, and other), the total
daily intake of the substance, arising from its use or uses at the
levels necessary to achieve the desired effect and from its
acceptable background in food, does not, in the opinion of the
Committee, represent a hazard to health. For this reason, and for
the reasons stated in individual evaluations, the establishment of
an acceptable daily intake (ADI) in mg/kg bw is not deemed
necessary.
REFERENCES
Institut Français de Recherches et Essais Biologiques (IFREB), No.
741008. Isomerized glucose produced from glucose. 1-Month
innocuity trial in the rat of the end product and intermediate
substances. Unpublished report submitted to WHO
Institut Français de Recherches et Essais Biologiques (IFREB), No.
751013. 3-Month oral toxicity study in the rat of a syrup of
isomerized glucose. Unpublished report submitted to WHO
See Also:
Toxicological Abbreviations