Studies on acute toxicity of methanol-utilizing bacteria and single cell protein produced by these bacteria were carried out with strains BNK-84, B-185 and BNS-25.
By single intraperitoneal administration of living cells, LD
50 values of methanol-utilizing bacteria were nearly equal to that of
Bacillus subtilis, being 1, 000 times that of
Pseudomonas aeruginosa.
By single intraperitoneal administration of killed cells (heat-treatment), LD
50 values of strains BNK-84 and B-185 were about 70∼120mg/kg mouse, being nearly equal to that of
Pseudomonas aeruginosa (LD
50=30mg/kg mouse). On the other hand, no death was observed with strain BNS-25 or
Bacillus subtilis for 14 days even at the largest dose, 220∼340mg/kg mouse.
By single intraperitoneal administration, LD
50 values of single cell protein derived from methanol-utilizing bacteria were approximately 1.6∼2.6g/kg mouse, being equal to those of
Bacillus subtilis and
Lactobacillus plantanum.
Single cell protein derived from methanol-utilizing bacteria did not cause any toxic sings for 14 days by single oral administration, even at the technically largest possible dose, 20g/kg mouse.
These results suggest that the methanol-utilizing bacteria are not pathogenic like
Bacillus subtilis and
Lactobacillus plantanum, and single cell protein produced therefrom by heat-drying has no acute toxicity.
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