The source and content of vitamin B12 in the tempehs.

Vitamin B12 contents were determined on 10 commercial tempeh samples purchased from various markets in Jakarta, Indonesia. A relatively high vitamin B12 content was found, i.e., 19 ng/g (ranges from 1.8 to 41.4 ng/g). As soybeans contain no vitamin B12, the amount of vitamin in the tempeh must therefore be derived from the other sources during the fermentation process. The tempeh prepared in the laboratory by inoculation of the commercial starter into the sterile soybean contained a much higher amount of vitamin B12, 127 ng/g (ranges from 122 to 136 ng/g). Pure mold and a single species of bacteria were isolated from the starter and commercial tempehs. Pure mold did not produce vitamin B12 in the sterile broth, soybean and medium used for vitamin B12 production. Only the isolated bacteria, identified as K. pneumoniae, could produce vitamin B12 in those substrates. The presence of mold did not significantly enhance or inhibit the vitamin B12 production by K. pneumoniae. It was, therefore, concluded that K. pneumoniae, the bacteria contaminated during the process of tempeh production, was responsible for the vitamin B12 production.

A simple and rapid diagnostic test for typhoid fever.

Barber protein sensitized latex particles were used in the latex agglutination test for the diagnosis of typhoid fever and the result compared with that of Widal 'O' and 'H' agglutination test. The latex agglutination test was positive in all 20 bacteriologically proved typhoid patients, in 81 of 85 (95.3%) typhoid suspected patients, and only in 2 of 85 (2.3%) blood donors. In contrast, the positive rates were 60% for both 'O' and 'H' Widal agglutinations in bacteriologically proved typhoid patients, 34.2% and 71.7% respectively in typhoid suspected patients, and none of blood donors were positive. The sensitivity and specificity of the latex agglutination test were 100% and 97.6% respectively with positive and negative predictive values of 90.9% and 100% respectively. The latex agglutination test may be particularly useful for the presumptive diagnosis of typhoid fever in remote health centres.