Chapter VII 



— 107 — 



Activities in Deposits 



Table XXX. — Numbers of bacteria which developed acrobically and anaerobically in marine 

 mud strata from dijjcrent depths. The redox capacity in terms of spontancojis or abiogcnic 

 oxygen absorption and the redox potential (intensity) in terms of E corrected to pH 7.0 are also 

 given {from ZoBell and Anderson, 1936b): — 



ways. Pearsall and Mortimer (1939) find that the states of iron, sul- 

 fur, and certain nitrogen compounds are functions of the redox potential 

 of mud. Reducing conditions created by bacterial processes are believed 

 by LovERiNG (1927) to promote the precipitation of copper, vanadium, 

 and other minerals. 



Factors influencing oxygen consumption: — Most bacteria consume 

 oxygen. The marine bacteria studied by Johnson (1936) consumed from 

 2.8 to 185 X io~^2 mgm. of oxygen per cell per hour as " resting cells" sus- 

 pended in sea water at 25° C. About one-fifth this quantity of oxygen 

 was consumed at 5° C, the Qio being 2.3 between 5° and 15° C. and 2.18 

 between 15° and 25° C. The addition of 0.04 per cent alginate increased 

 the oxygen uptake by from 7.9 to no per cent, while the addition of 0.04 

 per cent glucose effected an increase of from 10 to 378 per cent. 



By determining the amount of oxygen consumed by bacteria in sea 

 water and the number of bacteria present at any given time, ZoBell 

 (19406) estimated that marine bacteria multiplying in sea water consume 

 an average of 20.9 X io~^^ mgm. of oxygen per cell per hour at 22° C. The 

 rate of oxygen consumption was increased nearly four times when the sea 

 water was enriched with 0.05 per cent of asparagine or glucose. The rate 

 of oxygen consumption was found to be independent of the oxygen tension 

 within the examined range of between 0.43 and 17.84 mgm. of oxygen 

 per liter. 



The oxygen consumption of microorganisms in Lake Glubokoje, Rus- 

 sia, studied by Liagina and Kusnetzow (1937) ranged from 12.5 to 

 30.3 X io~^- mgm. per cell per hour for baciUi to 128 to 184 X lo"^^ mgm. 

 per cell per hour for torulae at 15° to 25° C. Their calculations clearly 

 show that the respiration of bacteria could account for the depletion of 

 oxygen from the bottoms of the lakes studied. 



Multiplying bacteria from Lake Mendota, Wisconsin, were found by 

 ZoBell and Stabler (19406) to consume from 51 to 93 X io~^- mgm. of 

 oxygen per cell per hour in freshly collected lake water at 25° C. The 

 rate decreased as oxidizable organic matter became a limiting factor, but 

 the rate of oxygen consumption was independent of the oxygen tension 

 within the examined ranges of 0.30 to 36 mgm. per liter. The rate of 

 respiration is a function of temperature, the Qio being 2.1 between 8° and 

 25° C. (ZoBell, 1940a). The effect of the quahty and quantity of or- 

 ganic matter upon the respiration of marine bacteria has been studied by 

 ZoBell and Grant (1943) who found that concentrations of organic 

 matter as low as o.io mgm. per hter are quantitatively utilized. 



