THE PRESENT STATUS OF SOME ASPECTS OF MARINE MICROBIOLOGY
165
A. Deterioration of nets, ropes, etc.
The deterioration of nets and ropes, resulting particularly in the loas
of teneile strength, has always been a serious problem and it has long
been recognized that microorganisms are the primary cause of the
decay. Recently synthetic fibres of various kinds (" nylon ", polypropylone, etc.) have been introduced for fishing nets, particularly
trawl and seine nets, but even so the latest available information
tends to show that materials made from natural fibres-cotton, hemp,
ramie, etc., are still used in vast quantities. In Japan about 8 years ago,
76% of such riets required replacing annually, mainly as a ;onsequence
of microbial deterioration (Kadota, 1956). The microorganisms
concerned are chiefly cellulose decomposing bacteria, although some
believe that fungi which attack lignin and cellulose are also partly
responsible for the deterioration of hemp and sisal cordage as well as of
piling and other wood structures in the sea. These cellulolytic microorganisms are almost universdly present in sea water and sea muds,
and the various enrichment media and methods suitable for their
isolation have been enumerated and described by Kadota (1956, 1959).
Most of the cellulolytic bacteria so far isolated are said to belong to the
Vibrio and Cytophaga groups, although a few Pseudomow, Micrococcus, Flavobacterium, Nocardia and Streptmyces spp. have also been
described (Kadota, 1056; Freitas and Bhat, 1964). Kadota (1966)
has supplied a key to the species of marine aerobic cellulose decomposing bacteria, including some sixteen new species isolated by him.
1. The distribution of cellulolytic bacteria in the sea
It is well recognized by fishermen that various waters differ in the
intensity of their attack on fishing nets; and indeed, t ~ s might be
expected, the distribution, both qualitatively and quantitatively is
affected by various environmental factors, such as season, geographical
area, pH, salinity, dissolved organic matter and suspended solids. Two
of the most recent studies well illustrate these points. Kadota (1966),
using cotton netting and working in Maizura and Hiroshima Bays in
Japan, found no definite seasonal cycles in the total abundance of
aerobic cellulose decomposers in sea water or muds. However, the types
of cellulose decomposers did appear to vary seasonally. During the
summer Vibrio purpureus and Vibrio aquamarinus predominated
because it appeared they grew between 20 to 36OC, and decomposed
rapidly at 30°C. On the other hand in the cold months of the
Year Vibrio marinojiavescem and Vibrio f u l w predominated ; they grew
well a t 20 to 26°C but failed to grow beyond 3OOC. Since the activity of
165
A. Deterioration of nets, ropes, etc.
The deterioration of nets and ropes, resulting particularly in the loas
of teneile strength, has always been a serious problem and it has long
been recognized that microorganisms are the primary cause of the
decay. Recently synthetic fibres of various kinds (" nylon ", polypropylone, etc.) have been introduced for fishing nets, particularly
trawl and seine nets, but even so the latest available information
tends to show that materials made from natural fibres-cotton, hemp,
ramie, etc., are still used in vast quantities. In Japan about 8 years ago,
76% of such riets required replacing annually, mainly as a ;onsequence
of microbial deterioration (Kadota, 1956). The microorganisms
concerned are chiefly cellulose decomposing bacteria, although some
believe that fungi which attack lignin and cellulose are also partly
responsible for the deterioration of hemp and sisal cordage as well as of
piling and other wood structures in the sea. These cellulolytic microorganisms are almost universdly present in sea water and sea muds,
and the various enrichment media and methods suitable for their
isolation have been enumerated and described by Kadota (1956, 1959).
Most of the cellulolytic bacteria so far isolated are said to belong to the
Vibrio and Cytophaga groups, although a few Pseudomow, Micrococcus, Flavobacterium, Nocardia and Streptmyces spp. have also been
described (Kadota, 1056; Freitas and Bhat, 1964). Kadota (1966)
has supplied a key to the species of marine aerobic cellulose decomposing bacteria, including some sixteen new species isolated by him.
1. The distribution of cellulolytic bacteria in the sea
It is well recognized by fishermen that various waters differ in the
intensity of their attack on fishing nets; and indeed, t ~ s might be
expected, the distribution, both qualitatively and quantitatively is
affected by various environmental factors, such as season, geographical
area, pH, salinity, dissolved organic matter and suspended solids. Two
of the most recent studies well illustrate these points. Kadota (1966),
using cotton netting and working in Maizura and Hiroshima Bays in
Japan, found no definite seasonal cycles in the total abundance of
aerobic cellulose decomposers in sea water or muds. However, the types
of cellulose decomposers did appear to vary seasonally. During the
summer Vibrio purpureus and Vibrio aquamarinus predominated
because it appeared they grew between 20 to 36OC, and decomposed
rapidly at 30°C. On the other hand in the cold months of the
Year Vibrio marinojiavescem and Vibrio f u l w predominated ; they grew
well a t 20 to 26°C but failed to grow beyond 3OOC. Since the activity of