1154 
About a third part of the weight of the carbonic acid corresponds 
to the oxidised petroleum. 
The velocity with which paraffin is oxidised by these bacteria 
was estimated by stating the diminution in weight, by the bacterial 
action, of two grams of paraffin, very minutely mixed with distilled 
water and anorganic salts, after a month’s culture at 28° CU. 
The rest of the originally added paraffin was dissolved in petro- 
leum-ether ; of this solution a certain quantity was evaporated and 
the remaining quantity of the paraffin was weighed. 
So it was found that during a month’s culture was oxidised in 
mers. by : 
Mycobactertum album 300 
‘ rubrum 330 
Micrococcus paraffinae 180 
B. fluorescens liquefaciéns 180 
Crude culture © 540 
Summary. 
1. Paraffins (petroleum, paraffin, benzine) can be used by certain 
species of microbes as source of carbon and energy, and are oxidised 
to carbonic acid and water. As intermediary products acid could be 
indicated. 
The bacteria were obtained by means of the accumulation method, 
with the said substances as source of carbon. 
2. The microbes active in this process belong to two groups. 
a. Fat-splitting bacteria, very common in nature, as B. fluorescens 
liquefaciens, B. pyocyaneus, B. punctatus, B. Stutzeri, B. lipolyticum, 
M. paraffinae. 
b. Non-fat-splitting bacteria belonging .to the genus Mycobacterium 
likewise widely spread, of which the following were distinguished : 
Mycobacterium album, M. phlei, M. lacticola, and M. rubrum. 
3. The paraffin-oxidising species decompose, on an average, 
15 mG. petroleum and 8 mm. paraffin in 24 hours at 28° C. per 
2 cm’. surface of culture liquid. 
Microbiological Laboratory of the 
Technical University, Delft. 
15 
Proceedings Rayal Acad. Amsterdam. Vol. XV. 
