Transcript Bacterial Ecology in Arthropod Digestive Tracts

Bacterial Ecology in Arthropod Digestive Tracts
Casey Eisele
Significance of Research

Arthropods aid in ruminant digestion

Little research has been conducted using
arthropods

Studies suggest that arthropods benefit from
both
– enzymatic activity (cellulose degradation)
– products of fermentation
Within the guts of Arthropods

Microbes have been isolated from cockroaches,
crickets, mealworms, desert millipedes, and scarab
beetles

Normal flora
– high ratio of microbes/biomass
– attachment to endothelium


cockroaches: 100 species
crickets:
25 species
Materials and Methods

Arthropods were sacrificed, sterilized and dissected

Bacteria was liberated from the lining of the gut
using a dilute solution of EDTA and sonication

1/10,000 dilutions were plated on
– T Soy Agar

Isolated bacteria were used to inoculate
– Phenol Red Broth
– Lactate Broth
– Cellulose plates and broth
Results

Bacteria were isolated from all three arthropod
species
T Soy Agar (Periplaneta americana)
Careful, they’re quick.

Isolated 5 species
– Underestimation
– Psychotolerant
T Soy Agar (Zophobas morio)

Isolated 2 species
T Soy Agar (Acheta dometicus)

Isolated 2 species
Populations and Diversity
My Data
Mealworm
Cockroach
10
9
8
7
6
5
4
3
2
1
0

Weight of gut
–
–
–
Cricket
(1x10 ^5 cfu/mg)
Bacterial Count
Bacteria/Biomass
Species

Cricket
= 2mg
Mealworm =54mg
Cockroach =25mg
# of species
2
2
>5
Bacteria/Biomass ratios confirmed
the findings of Cazemier et al. and
other studies
Biochemical Tests

1) Fermentation
Glycolytic Pathway
host/bacteria
bacteria
Lactose (6 C) — —> Lactate (3 C) —> Pyruvate,Acetic Acid, Ethanol
Phenol red broth
Lactate Broth
Results


Bacteria were isolated from all three arthropod
species
6 species fermented lactose
Glycolytic Pathway
Lactose

Cockroach
–
–
–
–
–

Species 1
Species 2
Species 3
Species 4
Species 5
no
proteolytic
Mealworm
–
–

—>
Species 6
Species 7
Cricket
–
–
Species 8
Species 9
proteolytic
Lactate —> Pyruvate/Acetic/Ethanol
Lactose Fermentation
lactose fermenters
control
proteolytic
proteolytic
cricket
mealworm
cockroach
Results

Bacteria were isolated from all three arthropod
species

6 species fermented lactose

All Bacteria reduced lactate
Glycolytic Pathway
Lactose

Cockroach
–
–
–
–
–

—> Lactate
Species
Species
Species
Species
Species
1
2
3
4
5
no
proteolytic
Mealworm
– Species 6
– Species 7

Cricket
– Species 8
– Species 9
proteolytic
—> Pyruvate/Acetic/Ethanol
Biochemical Tests

1) Fermentation

2) Cellulose Degradation
bacteria
Cellulose —> Simple Sugars (6 C)
Cellulose plate/broth
Cellulose Degradation
Cellulose tests
were inconclusive

Conclusions

My study confirmed the presence of large bacterial
populations living within the gut of arthropods

These bacteria exhibited the ability to ferment
compounds, whose end-products may be used by the
host for nutrition

Further testing would be needed to determine
cellulose-degrading capabilities
Acknowledgements
 Thank
You
– Professor Rose
– Professor Smith
– Tony