THE VENEZUELAN SALT-FISH INDUSTRIES 



under the same conditions o This indicated that after the longer growth period little or 

 none of the inoculated gelatin remained unchanged, 



Chromogeneaia 



The cultures of the reddening organism varied in color from pale pink to cherry-red. 

 In gelatin media, the coloration was more pronounced when beef extract or peptone had been 

 added. This showed that the protein constituents provided better conditions for the produc- 

 tion of pignent. In nutrient agar, those cultures which were grown at the prevailing room 

 temperature of 25° to 30° C exhibited a much darker coloration than those incubated at i*2°Co 

 Also, the nutrient agar media that contained 5 percent salt produced growth of deeper color 

 than those containing 0, 10, or 15 percent. 



Action on Nitrates 



Broth tubes and agar slants containing 0.1 percent potassium nitrate, 5 percent sodium 

 chloride, beef extract, and peptone were inoculated with the reddening organism and then 

 incubated at U20 C for four days. Absence of gas formation was indicated by the lack of 

 foam in the broth tubes and the non-appearaince of cracks in the agar slants. The test for 

 nitrite, through the use of sulphanilic acid and alpha-naphthylamine reagents, was negative. 



As good growths had been produced in the above-mentioned media, it was felt desirable to 

 determine whether the nitrate had been completely reduced beyond the nitrite stage. The 

 test for the presence of nitrates was carried out by adding a pinch of zinc dust to the 

 tubes to which the nitrite reagents had been added. The characteristic pink color which 

 developed after a few minutes showed that at least some of the nitrate had remained un- 

 reduced. 



Indole Production 



The test for indole was jjerformed by the method of Ehrlich and also by the Gore modi- 

 fication of that method. The medium used was a one percent solution of bacto-tryptone to 

 which had been added 5 percent of sodium chloride. The tests were carried out after incu- 

 bation at 42° C for one-day and four-day periods. There was good growth in all the in- 

 oculated tubes, but the tests for indole were negative. 



Action with Various Organic Compounds 



To characterize the reddening organism further tests were carried out to determine 

 whether it would produce gas or alter the pH of the substratum when grown in culture media 

 to which certain carbohydrates, alcohols, or glucosides had been added. According to Bergey 

 et al (1939), Paeudomonas sailinaria does not produce acid in media containing carbohydrate. 



The test compounds were dissolved in approximately four parts of water, and the acidity 

 was adjusted to a pH between 6,8 and 7.0, The various solutions were separately autoclaved 

 for 15 minutes at 15 pounds pressure, and then the containers were plunged into cold water. 

 Sufficient solution was added to the basal media to give a final concentration of the test 

 compound of 0.5 to 0,6 percent, and the pH was, then brought to between 6.8 and 7,0, The 

 basal media used were broth and agar, each containing beef-peptone plus 5 percent salt. 



Inoculations were made into Durham Termentation tubes and agar shake cultures so that 

 gas production could be detected. These cultures, along with uninoculated Durham-tube con- 

 trols, were then incubated at U2° C. The organism grew well in all the test media, but it 

 developed somewhat more luxuriantly, forming a surface ring or pellicle, in those cultures 

 that contained 1-arabinose, d-xylose , d-galactose, lactose, or dulcitol. After 72 hours 

 of incubation, there were no visible evidences of gas production in either the Durham fer- 

 mentation tubes or the agar shake cultures. 



After 3 and 8-day periods of incubation, the pH values of the media in both the in- 

 oculated and sterile Durham fermentation tubes were determined with a Beckman pH meter. 

 The results are summarized in Table 3, 



71 



