Should We Study Microbes at Microbial Scales, and If We Should, How Can We?

Michael Sieracki

Bigelow Laboratory for Ocean Sciences

Philosophy

• Scientists try to be rational, objective, and unbiased.

Philosophy

• Scientists try to be rational, objective, and unbiased.

• But scientists are human, and humans are irrational, subjective, and biased.

Philosophy

• Scientists try to be rational, objective, and unbiased.

• But scientists are human, and humans are irrational, subjective, and biased.

• Human minds are visual, and we like stories.

Philosophy

• Scientists try to be rational, objective, and unbiased.

• But scientists are human, and humans are irrational, subjective, and biased.

• Human minds are visual, and we like stories.

• So much of what we “know” about nature is based on good stories that hold together and are pleasing to us. Evidence and observations fit into these stories, so they are believable. But that does not make the stories true.

Wolpert, Lewis (1993, reprinted 2000)

The unnatural nature of science: why science does not make (common) sense.

Harvard University Press.

Advice

• Learn everything you can about your subject, from lectures, literature.

• Know it, but do not believe it (this is not religion).

• You must know the subject to judge when an idea or observation is new.

• Be skeptical of experts, do not believe what we tell you or what you read.

• Trust your own eyes, your own observations, over what someone else says or has written (especially experts).

• Question your instructors, make them uncomfortable, find out what they don’t know.

Plankton Orders of Magnitude

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

“Micro-liter-sphere”

.

1 microliter (µL)

= 1 cubic millimeter (mm3)

1 cm

VirusesViruses

BacteriaBacteria

PicophytoplanktonPicophytoplankton

FlagellatesFlagellates

CiliatesCiliates

DiatomsDiatoms

10,000

1,000

10

1

0.02

0.02

Number of organisms in 1 microliter of open ocean water

Dissolved Organic Matter

Small phytoplankton

Bacteria

Flagellates Ciliates

Microbial Food Web

All forms produce dissolved organic matter

In every microliter of seawater there are all the organisms for a complete, functional ecosystem.

These organisms form the fabric of life in the sea - the other organisms are embroidery on this fabric.

“Microliter-sphere”

“Microlitersphere”

• Nice story, but….

“Microlitersphere”

• Nice story, but….

• Is it true??

“Microlitersphere”

• Nice story, but….

• Is it true??

• What could be wrong with this picture?

“Microlitersphere”

• Nice story, but….

• Is it true??

• What could be wrong with this picture?

• Hint: what are the assumptions?

DAPI stained bacteria

Polymer Gels

Tanaka 1993

Polymer gels are naturally produced and dispersed in seawater

dispersion

assembly

1 nm

fragmentation

annealing

1 um

Macro-molecules

Nanogel

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Microgel

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+Ca2+

Orellana and Verdugo 2003

Azam Impressionist View1998 Science 280:694-696

• “Organic matter continuum”

• Dissolved to particulate

Bacterial clustering around protists

• Darkfield microscopy

Blackburn et al. 1998

Science 282:2254-2256

Should we study microbes at microbial scales?

……… if so ……. how?