156
ROBINA B. SCHOLES AND J. M. SHEWAN
Vibrio purpureus was generally much higher than that of Vibrio
marinoflavescens, the gencral variation in the rates of deterioration of
the cotton nets could easily be explained.
Cellulose decomposers were usually more abundant in surface than
in the deeper waters and still more abundant in the muds. An interesting
feature noted by Kadota was that Cytophuga spp. in sea watcr accounted
for anything from 0 to 33% of the total cellulolytic flora and that the
numbers of cytophagas seemed to parallel the abundance of plankton
or suspended matter in the sea, bccause these organisms are epiphytic
in habit. When fishing nets were immersed for a period of 10 days in
sea water Kadota found that the number of Cytophugn spp. present
rose to about twice that found in the sea water itself; again possibly due
to the epiphytic characteristics of the Cytophaga spp. Kadota also
found that when nets were stored dry, with moisture contents ranging
from about 7 to 11%, for periods of up to 48 days, the C y t o p w a spp.
accounted for about 60 to 80% of the survivors. Such treatment,
more particularly if often repeated, would undoubtedly lead to an
enrichment in the flora in Cytophaga spp. As Kadota says (1956, 1959)
there is much reason to believe that the Cytophaga spp. are the most
active group in the deterioration of nets, ropes, etc., made from natural
fibres.
Brandt (1954) has also been studying the rotting of fishing nets in
stagnant and free flowing water in the Baltic and North Sea. He found
that deterioration was greater in flowing waters than in stagnant ones,
and that irrespective of the degree of pollution or of eutrophy, there was
a marked correlation with temperature, deterioration decreasing
sharply below 5°C. In stagnant surface waters, the amount of rotting
was greater in eutrophic waters than in oligotrophic ones and in
summer than in winter. In the North Sea deterioration decreased
with increasing distance from the shore. Kadota on the other hand in
Maizura and Hiroshima Bays found distance from the land had no
direct effect on the populntion of cellulolytic bacteria or in the bottom
deposits, but as can be deduced from the above discussion it does not
necessarily follow that the rate of deterioration of the nets immersed
in such waters always correIates with numbers of organisms isolated
by culture methods.
2. Node of cellulose brmkdown
It is now believed that the breakdown of cellulose under microbial
attack can take place in two ways : (1) there is a continuous lopping-off
from the end of the chain of glucose units, of short terminal sections
mnbining from one to a few glucose units; or (2) the chain is split
ROBINA B. SCHOLES AND J. M. SHEWAN
Vibrio purpureus was generally much higher than that of Vibrio
marinoflavescens, the gencral variation in the rates of deterioration of
the cotton nets could easily be explained.
Cellulose decomposers were usually more abundant in surface than
in the deeper waters and still more abundant in the muds. An interesting
feature noted by Kadota was that Cytophuga spp. in sea watcr accounted
for anything from 0 to 33% of the total cellulolytic flora and that the
numbers of cytophagas seemed to parallel the abundance of plankton
or suspended matter in the sea, bccause these organisms are epiphytic
in habit. When fishing nets were immersed for a period of 10 days in
sea water Kadota found that the number of Cytophugn spp. present
rose to about twice that found in the sea water itself; again possibly due
to the epiphytic characteristics of the Cytophaga spp. Kadota also
found that when nets were stored dry, with moisture contents ranging
from about 7 to 11%, for periods of up to 48 days, the C y t o p w a spp.
accounted for about 60 to 80% of the survivors. Such treatment,
more particularly if often repeated, would undoubtedly lead to an
enrichment in the flora in Cytophaga spp. As Kadota says (1956, 1959)
there is much reason to believe that the Cytophaga spp. are the most
active group in the deterioration of nets, ropes, etc., made from natural
fibres.
Brandt (1954) has also been studying the rotting of fishing nets in
stagnant and free flowing water in the Baltic and North Sea. He found
that deterioration was greater in flowing waters than in stagnant ones,
and that irrespective of the degree of pollution or of eutrophy, there was
a marked correlation with temperature, deterioration decreasing
sharply below 5°C. In stagnant surface waters, the amount of rotting
was greater in eutrophic waters than in oligotrophic ones and in
summer than in winter. In the North Sea deterioration decreased
with increasing distance from the shore. Kadota on the other hand in
Maizura and Hiroshima Bays found distance from the land had no
direct effect on the populntion of cellulolytic bacteria or in the bottom
deposits, but as can be deduced from the above discussion it does not
necessarily follow that the rate of deterioration of the nets immersed
in such waters always correIates with numbers of organisms isolated
by culture methods.
2. Node of cellulose brmkdown
It is now believed that the breakdown of cellulose under microbial
attack can take place in two ways : (1) there is a continuous lopping-off
from the end of the chain of glucose units, of short terminal sections
mnbining from one to a few glucose units; or (2) the chain is split