Ward also included some examples for photosynthetic microbial symbioses
which then were known in animals. Those were the mutualistic association between
sponges and what we now term cyanobacteria, and the mutualistic association
between Hydra and its endosymbiont algae Chlorella. He included among those
animals the “Green Infusoria”, for which I presume he intended relationships such as
the endosymbiotic cyanobacteria that exist in amoeba of the genus Paulinella. We
now consider amoeba to be protists rather than animals.
Ward indicated that another example of derived advantage might be when an
aerobic microorganism prevents the access of oxygen to an anaerobic microorganism. In this regard, he mentioned the fixation of atmospheric nitrogen accomplished
by Clostridium pasteurianum as facilitated by other organisms that can scavage
oxygen to create adequately anaerobic conditions for the Clostridium. The
scavanging of oxygen is important because the nitrogenase which fixes nitrogen is
rapidly degraded by oxygen.
Ward talked about ‘metabiosis’ as representing instances when one organism
prepares a more suitable environment for another. We now consider metabiosis to be
a form of commensalism. Wards examples of metabiosis included when one species
modifies a substance, after which a different organism subsequently can utilize that
modified substance, with this representing the provision of definite food materials by
one for the other. His suggestion was that these metabiotic associations might be a
‘half-way house’ to symbiosis, with an example being when one organism can
hydrolyze starch via diastase although the subsequent build-up of sugar eventually
might become enzymatically inhibitory, after which another organism would ferment the sugar to alcohol and thereby remove the inhibition. We now use the term
diastase in reference to any α-, β-, or γ-amylase, which are hydrolases capable of
breaking down carbohydrate. The specific example which Ward gave was for sake
production, when Aspergillus acts upon the starch in rice, which prepares the way for
yeast to then ferment the sugar into alcohol.
Ward also suggested that there might be mutualistic cooperations in which either
species could ‘carry on’ alone in a given situation although they did better when
acting together. We now define ‘mutualism’ as representing relationships when each
organism derives a net benefit. ‘Commensal’ is a relationship in which one species
gains benefit while the other is not necessarily harmed. Ward suggested the term
‘Antibiosis’ to represent antagonism.
Ward was a prolific writer, and in that same Annals of Botany volume he included
the third part in his series of articles about the microorganisms found in the Thames
River (Ward 1899a) plus information on methods for culturing algae (Ward 1899c).
14 Discovering the Symbiotic Nature of Microbial Life: Summarizing Milestone. . .
231
which then were known in animals. Those were the mutualistic association between
sponges and what we now term cyanobacteria, and the mutualistic association
between Hydra and its endosymbiont algae Chlorella. He included among those
animals the “Green Infusoria”, for which I presume he intended relationships such as
the endosymbiotic cyanobacteria that exist in amoeba of the genus Paulinella. We
now consider amoeba to be protists rather than animals.
Ward indicated that another example of derived advantage might be when an
aerobic microorganism prevents the access of oxygen to an anaerobic microorganism. In this regard, he mentioned the fixation of atmospheric nitrogen accomplished
by Clostridium pasteurianum as facilitated by other organisms that can scavage
oxygen to create adequately anaerobic conditions for the Clostridium. The
scavanging of oxygen is important because the nitrogenase which fixes nitrogen is
rapidly degraded by oxygen.
Ward talked about ‘metabiosis’ as representing instances when one organism
prepares a more suitable environment for another. We now consider metabiosis to be
a form of commensalism. Wards examples of metabiosis included when one species
modifies a substance, after which a different organism subsequently can utilize that
modified substance, with this representing the provision of definite food materials by
one for the other. His suggestion was that these metabiotic associations might be a
‘half-way house’ to symbiosis, with an example being when one organism can
hydrolyze starch via diastase although the subsequent build-up of sugar eventually
might become enzymatically inhibitory, after which another organism would ferment the sugar to alcohol and thereby remove the inhibition. We now use the term
diastase in reference to any α-, β-, or γ-amylase, which are hydrolases capable of
breaking down carbohydrate. The specific example which Ward gave was for sake
production, when Aspergillus acts upon the starch in rice, which prepares the way for
yeast to then ferment the sugar into alcohol.
Ward also suggested that there might be mutualistic cooperations in which either
species could ‘carry on’ alone in a given situation although they did better when
acting together. We now define ‘mutualism’ as representing relationships when each
organism derives a net benefit. ‘Commensal’ is a relationship in which one species
gains benefit while the other is not necessarily harmed. Ward suggested the term
‘Antibiosis’ to represent antagonism.
Ward was a prolific writer, and in that same Annals of Botany volume he included
the third part in his series of articles about the microorganisms found in the Thames
River (Ward 1899a) plus information on methods for culturing algae (Ward 1899c).
14 Discovering the Symbiotic Nature of Microbial Life: Summarizing Milestone. . .
231