van Leewenhoeck’s publication (van Leewenhoeck 1677) mostly was about the
microoganisms that could be seen by examining water droplets. Our planets simplest
life forms do create some impressive, although not always favorably appreciated,
communal aquatic displays that are know as freshwater microbial scums and slimes.
Those particular displays are produced by algae including the diatoms, bacteria
including the cyanobacteria, and the participation list progresses to the upwardly
mobile protozoa and zooplankton. Aquatic displays do go upscale, to exhibitions of
floating macroscopic plants including the duckweeds (Lemna, Spirodela), water
meal (Wolffia), and water fern (Azolla) as photographically described by Kannan
and Lenca (2013) and all of which have vital associations with microorganisms.
Perhaps one of the bigest advances in understanding microbial processes was
made by Sergei Nikolaievich Winogradsky during a time period when Winogradsky
was working with Heinrich Anton de Bary at the University of Strasbourg. There,
Winogradsky discovered lithotrophy when he found that Beggiatoa can form intracellular sulfur deposits by oxidizing hydrogen sulfide (Winogradsky 1887).
Beggiatoa are able to use reduction as a means of generating hydrogen sulfide
from gypsum, which is calcium sulfate dihydrate. They then can form sulfur by
using internally stored nitrate to oxidize the hydrogen sulfide. The sulfur is further
oxidized and releasing as sulfuric acid into the surrounding water. Biogenic sulfuric
acid corrosion unfortunately causes damage to sewerage and wastewater treatment
facilities. Beggiatoa typically are considered to be aquatic microbes, although they
also can use molecular oxygen to oxidize hydrogen sulfide in the rhizosphere of
swamp plants, releasing water and elemental sulfur. In the presence of oxygen,
Beggiatoa can heterotrophically gain energy by oxidizing organic compounds to
carbon dioxide.
One of the most complex outcomes from microbial metabolism has been the
creation of soil. Soil represents the foundation, both physically and figuratively, for
terrestrial life. We also have needed to understand, and we should never forget, the
importance of microorganisms in sustaining those characteristics of soil upon which
much of evolution has relied.
Helen Cecilia De Silver Abbott explained to a general audience the state of
knowledge in plant biochemistry (Abbott HC de 1887). I would summarize her
presentation as being that plants combined four basic elements, which were carbon,
hydrogen, oxygen, and nitrogen, grouping these elements with each other along with
sulphur, phosphorus, and ash-elements derived from the mineral world. She mentioned the concept of plant evolution, and that the soil supplied what was needed by
the plants. But, notably missing from her presentation was mention of microbiology.
Indeed, at that time soil was considered by many as being almost a magical resource.
We knew that soil could be healthy, and that repeated agricultural use often depleted
soil of its healthiness, but we did not understand that it was the microbial players
contained in soil and their roles which made the soil healthy. Soil is in fact a magical
resource, but the magic in soil comes from the interactivity of its microbes and their
macrobial symbionts.
Forty years later, our understanding of soil microbiology had advanced to the
point that Selman Abraham Waksman was able to published what seems to have
6
C. J. Hurst
microoganisms that could be seen by examining water droplets. Our planets simplest
life forms do create some impressive, although not always favorably appreciated,
communal aquatic displays that are know as freshwater microbial scums and slimes.
Those particular displays are produced by algae including the diatoms, bacteria
including the cyanobacteria, and the participation list progresses to the upwardly
mobile protozoa and zooplankton. Aquatic displays do go upscale, to exhibitions of
floating macroscopic plants including the duckweeds (Lemna, Spirodela), water
meal (Wolffia), and water fern (Azolla) as photographically described by Kannan
and Lenca (2013) and all of which have vital associations with microorganisms.
Perhaps one of the bigest advances in understanding microbial processes was
made by Sergei Nikolaievich Winogradsky during a time period when Winogradsky
was working with Heinrich Anton de Bary at the University of Strasbourg. There,
Winogradsky discovered lithotrophy when he found that Beggiatoa can form intracellular sulfur deposits by oxidizing hydrogen sulfide (Winogradsky 1887).
Beggiatoa are able to use reduction as a means of generating hydrogen sulfide
from gypsum, which is calcium sulfate dihydrate. They then can form sulfur by
using internally stored nitrate to oxidize the hydrogen sulfide. The sulfur is further
oxidized and releasing as sulfuric acid into the surrounding water. Biogenic sulfuric
acid corrosion unfortunately causes damage to sewerage and wastewater treatment
facilities. Beggiatoa typically are considered to be aquatic microbes, although they
also can use molecular oxygen to oxidize hydrogen sulfide in the rhizosphere of
swamp plants, releasing water and elemental sulfur. In the presence of oxygen,
Beggiatoa can heterotrophically gain energy by oxidizing organic compounds to
carbon dioxide.
One of the most complex outcomes from microbial metabolism has been the
creation of soil. Soil represents the foundation, both physically and figuratively, for
terrestrial life. We also have needed to understand, and we should never forget, the
importance of microorganisms in sustaining those characteristics of soil upon which
much of evolution has relied.
Helen Cecilia De Silver Abbott explained to a general audience the state of
knowledge in plant biochemistry (Abbott HC de 1887). I would summarize her
presentation as being that plants combined four basic elements, which were carbon,
hydrogen, oxygen, and nitrogen, grouping these elements with each other along with
sulphur, phosphorus, and ash-elements derived from the mineral world. She mentioned the concept of plant evolution, and that the soil supplied what was needed by
the plants. But, notably missing from her presentation was mention of microbiology.
Indeed, at that time soil was considered by many as being almost a magical resource.
We knew that soil could be healthy, and that repeated agricultural use often depleted
soil of its healthiness, but we did not understand that it was the microbial players
contained in soil and their roles which made the soil healthy. Soil is in fact a magical
resource, but the magic in soil comes from the interactivity of its microbes and their
macrobial symbionts.
Forty years later, our understanding of soil microbiology had advanced to the
point that Selman Abraham Waksman was able to published what seems to have
6
C. J. Hurst