154
ROBINA B. SCHOLEY AND J . M. SHEWAN
VIl. DETERIORATION OF MATERIALS AND SPOILAGE OF FISH
In this connectioii, we are coiiccrned primarily with biodeterioration
more particularly since in the destruction of nets, ropes, and wood
abiogenic factors such as oxidation, light and salt play a very minor
role. It has recently been suggested (H. J. Hueck, personal communication) that there are at least two ways in which microorganisms
are concerned in biodeterioration : (1) they may attack the material,
nets, wood, metals, etc., chemically, (2) they may only foul the surfaces
as in ship hulls, where bacteria are said to be initially concerned in the
production of the primary film paving the way for later colonization
by other organisms.
In the former case the materials may serve as nutrients for the
microorganisms resulting in changes in their mechanical, chemical
or electrical properties ; a good example is the loss of tensile strength
of fishing nets made from natural fibres, due to activities of cellulose
decomposing bacteria andlor fungi. This type of attack has been
called " assimilatory " in contrast to the " dissimilatory " one in which
the products of microbial metabolisms, such as the production of acid,
could result in the pitting, discoloration, breaking, etc., of the material
attacked. A good example of this latter type of attack is the corrosion of metals by sulphate reducing bacteria.
For all such micro-organisms, be they of the assimilatory or dissimilatory type, the term " hylopathogon " has been suggested. (H. J.
Hueck, personal communication). A hylopathogen as such should
conform to the Koch principles of (1) being present in the materials
showing the biodeterioration phenomenon under investigation ; (2)
being capable of isolation in pure culture from such material ; and (3)
producing, under controlled conditions in pure culture, the biodeterioration phenomenon comparable to that under investigation.
Unfortunately, few of the organisms said to be involved in biodeterioration and described in the literature appear to have been
tested for conformity to these three principles. However, it is to be
expected that once the recently formed International Group on biodeterioration, working under the auspices of O.E.C.D., gets under way,
such data may soon become available. Apart from their imprecise role
in fouling of surfaces, ships hulls, etc., marine bacteria are involved in
the deterioration of ropes, canvas, fishing nets and possibly of wood,
concrete and metal surfaces, and cables. The spoilage of fi8h after
capture may be looked upon as a special case of assimilatory biodeterioration.
ROBINA B. SCHOLEY AND J . M. SHEWAN
VIl. DETERIORATION OF MATERIALS AND SPOILAGE OF FISH
In this connectioii, we are coiiccrned primarily with biodeterioration
more particularly since in the destruction of nets, ropes, and wood
abiogenic factors such as oxidation, light and salt play a very minor
role. It has recently been suggested (H. J. Hueck, personal communication) that there are at least two ways in which microorganisms
are concerned in biodeterioration : (1) they may attack the material,
nets, wood, metals, etc., chemically, (2) they may only foul the surfaces
as in ship hulls, where bacteria are said to be initially concerned in the
production of the primary film paving the way for later colonization
by other organisms.
In the former case the materials may serve as nutrients for the
microorganisms resulting in changes in their mechanical, chemical
or electrical properties ; a good example is the loss of tensile strength
of fishing nets made from natural fibres, due to activities of cellulose
decomposing bacteria andlor fungi. This type of attack has been
called " assimilatory " in contrast to the " dissimilatory " one in which
the products of microbial metabolisms, such as the production of acid,
could result in the pitting, discoloration, breaking, etc., of the material
attacked. A good example of this latter type of attack is the corrosion of metals by sulphate reducing bacteria.
For all such micro-organisms, be they of the assimilatory or dissimilatory type, the term " hylopathogon " has been suggested. (H. J.
Hueck, personal communication). A hylopathogen as such should
conform to the Koch principles of (1) being present in the materials
showing the biodeterioration phenomenon under investigation ; (2)
being capable of isolation in pure culture from such material ; and (3)
producing, under controlled conditions in pure culture, the biodeterioration phenomenon comparable to that under investigation.
Unfortunately, few of the organisms said to be involved in biodeterioration and described in the literature appear to have been
tested for conformity to these three principles. However, it is to be
expected that once the recently formed International Group on biodeterioration, working under the auspices of O.E.C.D., gets under way,
such data may soon become available. Apart from their imprecise role
in fouling of surfaces, ships hulls, etc., marine bacteria are involved in
the deterioration of ropes, canvas, fishing nets and possibly of wood,
concrete and metal surfaces, and cables. The spoilage of fi8h after
capture may be looked upon as a special case of assimilatory biodeterioration.