THE PRESENT STATUS OF SOME ASPECTS OF MARINE MIOROBIOLOOY
151
" psychrophile " was first used in 1902 by Schmidt-Nielsen to describe
such organisms. As mentioned earlier, it was later shown that many
marine types not only grow well a t 0°C but are also very heat labile
(ZoBell and Conn, 1940 ; Hayes, 1963), many being killed within 10 min
at 30°C (ZoBell and Conn 1940). However, it has only very recently been
recognized that there are some types, found particularly in the Polar
seas and soils, which cannot tolerate temperatures much above 15°C.
Since the introduction of refrigerated storage for materials such
blood and plasma it has been found that there are also several types of
mesophilic bacteria with growth optima about 37°C which can grow,
albeit slowly, in the region of 0 to 6°C. Accordingly, there has been some
confusion over the term '' psychrophilic " or cold loving. As with the
halophiles it might be appropriate to define those types which grow at
the region of O'C, but have growth optima of 20" and beyond as
" psychrotolerant ", restricting " pschrophilic " to these species
having growth optima somewhat below 20°C. Extreme psychrophiles
might, therefore, be reserved for types having maxima between 16 and
20°C (see Stokes, 1962).
The physiological basis for psychrophility in marine bacteria has
not yet been worked out although there is much research activity in this
field (Rose, 1062; Ingraham, 1962; Stokes, 1962; Morita and Burton,
1963 ; and Burton and Morita, 1963). The most obvious explanation
is that true psychrophiles have exceptionally heat labile enzymes,
whose inactivation leads directly to cessation of growth, aa found by
Morita and Burton (1963) for the malic dehydrogenase of a marine
Vibrio sp. Others believe that there may be an accumulation of a
metabolic poison at the higher temperatures. As Morita and Burton
(1963) point out, however, there are in all probability many factors
involved, in addition to the heat lability of the essential enzymes or to
cell permeability, which only further work will elucidate.
D. Luminous bacteria
Luminescence is one of the most beautiful and fascinating properties
of living things, ranging from bacteria to fish, in the marine environment. The burning of the sea, so long a mystery to fishermen and sailors
generally, is now known to be due to the presence of large numbera of
dinoflagellates, which lumiliesce when disturbed. During World War 11,
the Japanese used dried Cypridinae, small crustaceans, aa a source of low
intensity light where a flash lamp might have given their positions away.
This powder, when moistened in the palm of the hand, gives enough
light to read a message, a watch or a map. It haa also been known for
Some time that marine fish, and other animals such rn squid, when
.(.Y.n.-Z
?
151
" psychrophile " was first used in 1902 by Schmidt-Nielsen to describe
such organisms. As mentioned earlier, it was later shown that many
marine types not only grow well a t 0°C but are also very heat labile
(ZoBell and Conn, 1940 ; Hayes, 1963), many being killed within 10 min
at 30°C (ZoBell and Conn 1940). However, it has only very recently been
recognized that there are some types, found particularly in the Polar
seas and soils, which cannot tolerate temperatures much above 15°C.
Since the introduction of refrigerated storage for materials such
blood and plasma it has been found that there are also several types of
mesophilic bacteria with growth optima about 37°C which can grow,
albeit slowly, in the region of 0 to 6°C. Accordingly, there has been some
confusion over the term '' psychrophilic " or cold loving. As with the
halophiles it might be appropriate to define those types which grow at
the region of O'C, but have growth optima of 20" and beyond as
" psychrotolerant ", restricting " pschrophilic " to these species
having growth optima somewhat below 20°C. Extreme psychrophiles
might, therefore, be reserved for types having maxima between 16 and
20°C (see Stokes, 1962).
The physiological basis for psychrophility in marine bacteria has
not yet been worked out although there is much research activity in this
field (Rose, 1062; Ingraham, 1962; Stokes, 1962; Morita and Burton,
1963 ; and Burton and Morita, 1963). The most obvious explanation
is that true psychrophiles have exceptionally heat labile enzymes,
whose inactivation leads directly to cessation of growth, aa found by
Morita and Burton (1963) for the malic dehydrogenase of a marine
Vibrio sp. Others believe that there may be an accumulation of a
metabolic poison at the higher temperatures. As Morita and Burton
(1963) point out, however, there are in all probability many factors
involved, in addition to the heat lability of the essential enzymes or to
cell permeability, which only further work will elucidate.
D. Luminous bacteria
Luminescence is one of the most beautiful and fascinating properties
of living things, ranging from bacteria to fish, in the marine environment. The burning of the sea, so long a mystery to fishermen and sailors
generally, is now known to be due to the presence of large numbera of
dinoflagellates, which lumiliesce when disturbed. During World War 11,
the Japanese used dried Cypridinae, small crustaceans, aa a source of low
intensity light where a flash lamp might have given their positions away.
This powder, when moistened in the palm of the hand, gives enough
light to read a message, a watch or a map. It haa also been known for
Some time that marine fish, and other animals such rn squid, when
.(.Y.n.-Z
?