THE PRESENT STATUS OF SOME ASPECTS OF MARINE MIQROBIOLOOY
137
C . The submerged slide or fouling technique
Another method for the enumeration and isolation of bacteria in
situ at various depths in the ocean, is the submerged slide or fouling
tcchniquc, based on that of Kholodny’s (1930) for soils and Henrici’s
(1933) for fresh water (ZoBell, 1946; Kriss, 1963). Kriss (1963) made
extensive use of it, more particularly in his attempts to calculate the
annual biomass production in various oceans throughout the world.
Sterile glsss slides, usually about 50 x 76 mm, attached to holders
fixed to a hydrological cable are immersed at various depths and after
known periods of time, ranging from hours to several days, are removed
and examined by direct microscopy. The method, in experienced
hands, can give valuable information both of numbers and types of
bacteria at desired positions at any one time.
111. MEDIA
The choice of media poses many problems and the adage that the
composition, along with the cultural conditions such as temperature,
osmotic pressure, pH and salinity, should simulate the natural environment holds good here as elsewhere. It is almost impossible to generalize,
since the numbers and types of media proposed for the investigation of
marine waters, muds, ete., arc legion. For special physiological groups of
bacteria, such as sulphate and nitrate reducers, and cellulose, starch,
alginate or chitin digesters, the reader is referred to the various monographs on marine microbiology for details (see Benecke, 1933; ZoBell,
1946; Brisou, 1955; and Kriss, 1963).
So far as the heterotrophs are concerned it is obvious that the most
successful media should be based on knowledge concerning the growth
requirements of these bacteria. Unfortunately few data of this kind
exist but if MaeLeod et aZ.’s (1954) organisms are at all typical, then
many marine heterotrophs require in addition to the ions normally
present in sea water-such as sodium, potassium, magnesium, sulphate,
phosphate and traces of iron-organic sources of carbon as in various
amino acids, and certain vitamins, mainly of the B complex. Consequently, it is not surprising that the most successful media are based on
sea water, peptone and yeast extract. The amount of peptone andlor
Yeast extract required depends on the biological status of the sample
under investigation, which, even at the same sampling station, may
vary markedly from season to season. As ZoBell(l946) discovered many
Years ago, natural sea water has to be aged, usually for about 3 months,
Preferably in the dark, to avoid growth of photosynthetic organiama,
and to get rid of inhibitory factors, before being used in media making.
137
C . The submerged slide or fouling technique
Another method for the enumeration and isolation of bacteria in
situ at various depths in the ocean, is the submerged slide or fouling
tcchniquc, based on that of Kholodny’s (1930) for soils and Henrici’s
(1933) for fresh water (ZoBell, 1946; Kriss, 1963). Kriss (1963) made
extensive use of it, more particularly in his attempts to calculate the
annual biomass production in various oceans throughout the world.
Sterile glsss slides, usually about 50 x 76 mm, attached to holders
fixed to a hydrological cable are immersed at various depths and after
known periods of time, ranging from hours to several days, are removed
and examined by direct microscopy. The method, in experienced
hands, can give valuable information both of numbers and types of
bacteria at desired positions at any one time.
111. MEDIA
The choice of media poses many problems and the adage that the
composition, along with the cultural conditions such as temperature,
osmotic pressure, pH and salinity, should simulate the natural environment holds good here as elsewhere. It is almost impossible to generalize,
since the numbers and types of media proposed for the investigation of
marine waters, muds, ete., arc legion. For special physiological groups of
bacteria, such as sulphate and nitrate reducers, and cellulose, starch,
alginate or chitin digesters, the reader is referred to the various monographs on marine microbiology for details (see Benecke, 1933; ZoBell,
1946; Brisou, 1955; and Kriss, 1963).
So far as the heterotrophs are concerned it is obvious that the most
successful media should be based on knowledge concerning the growth
requirements of these bacteria. Unfortunately few data of this kind
exist but if MaeLeod et aZ.’s (1954) organisms are at all typical, then
many marine heterotrophs require in addition to the ions normally
present in sea water-such as sodium, potassium, magnesium, sulphate,
phosphate and traces of iron-organic sources of carbon as in various
amino acids, and certain vitamins, mainly of the B complex. Consequently, it is not surprising that the most successful media are based on
sea water, peptone and yeast extract. The amount of peptone andlor
Yeast extract required depends on the biological status of the sample
under investigation, which, even at the same sampling station, may
vary markedly from season to season. As ZoBell(l946) discovered many
Years ago, natural sea water has to be aged, usually for about 3 months,
Preferably in the dark, to avoid growth of photosynthetic organiama,
and to get rid of inhibitory factors, before being used in media making.