Bacteria may display variable nutritional requirements. Certain bacteria can grow well in only dextrose with several mineral salts. Others require, in addition to these, amino acid, purine, pyrimidine, vita-min or hemin. However, what fulfills nutrient generally in most kinds of bacteria in different suituations is complex organic nitrogen compounds and extracts.
While the importance of nitrogenous substances for bacterial growth was recognized early in the development of the bacteriological media, it was also realized that bacteria could not always obtain their nitrogen requirements directly from protein.
A variety of procedures, such as hydrolysis with alkali, acid, enzymatic digestion, partial digestion of plasma, et al.,have been used for the preparation of protein hydrolysates. When subjected to hydrolysis proteins yield metaproteins, proteoses, peptones, polypeptides, and finally, the chemically simpler amino acids and their analogs. All bacteriological peptones are mixtures of various products of protein hydrolysis. In general, proteinaceous materials used for the digestion are of either animal or plant origin: muscle, liver, milk, casein, blood, and soybean meal. In Korea, cattlefish are also a good nitrogen source that can be obtained economically, as compared with the above materials. The protein content of the fresh cattlefish (Ommastrephes sloanei pacificus) was 17. 5%. It would be desirable to obtain the excellent digest of cattlefish for the cultivation of bacteria.
The present report concerns the nutritive value of the cattlefish and the effects of the digest as a major component of a medium on the various bacterial growths.
The digests were prepared with pepsin, papain, and pancreatin respectively, under various conditions and made into a bacteriological medium, including NaCl and Na2HPO4.
Biochemical tests and bacteriological tests with Vibrio, Salmonella, Shigella, Staphylococcus, fi?Streptococcus, D. pneumoniae, B. pertussis, and C. diphtheriae were performed on the cuttlefish medium. The results of these experiments are as follows.
1. The digests prepared with papain, pepsin, and pancreatin supported good growths of Vibrio, Salmonella, Shigella, and Staphylococcus. Among these digests the papaic digest was best.
2. The baeteria grow best where the amount of amino nitrogen to total nitrogen of the digest is about 1:4.
3. The bacterial growth was more stimulated in the digests treated with bovine blood cells, active carbon, or starch and the digests with added dextrose.
4. The bacterial growth was most. Stimulated in the digests with both these treatments and addition of dextrose.
5. The digests were free from fermentable carbohydrate. The indole, acetylmethylcarbinol, and H2S were produced in the digests inoculated with E. coli, E. coli, A. aerogenes, and S. typhi respectively. The digest of cattlefish may be useful as a medium for the bacterial cultivation.
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