Bacterial Ecology in Arthropod Digestive Bacterial Ecology in Arthropod Digestive TractsTracts

Casey EiseleCasey Eisele

Significance of ResearchSignificance of Research Arthropods aid in ruminant digestionArthropods aid in ruminant digestion

Little research has been conducted using Little research has been conducted using arthropodsarthropods

Studies suggest that arthropods benefit Studies suggest that arthropods benefit from bothfrom both– enzymatic activity (cellulose degradation)enzymatic activity (cellulose degradation) – products of fermentationproducts of fermentation

Within the guts of ArthropodsWithin the guts of Arthropods

Microbes have been isolated from Microbes have been isolated from cockroaches, crickets, mealworms, desert cockroaches, crickets, mealworms, desert millipedes, and scarab beetles millipedes, and scarab beetles

Normal flora Normal flora – high ratio of microbes/biomasshigh ratio of microbes/biomass– attachment to endotheliumattachment to endothelium

cockroaches: 100 speciescockroaches: 100 species crickets: 25 speciescrickets: 25 species

Materials and MethodsMaterials and Methods Arthropods were sacrificed, sterilized and dissectedArthropods were sacrificed, sterilized and dissected

Bacteria was liberated from the lining of the gut using a Bacteria was liberated from the lining of the gut using a dilute solution of EDTA and sonicationdilute solution of EDTA and sonication

1/10,000 dilutions were plated on1/10,000 dilutions were plated on– T Soy AgarT Soy Agar

Isolated bacteria were used to inoculate Isolated bacteria were used to inoculate – Phenol Red BrothPhenol Red Broth– Lactate BrothLactate Broth– Cellulose plates and brothCellulose plates and broth

ResultsResults

Bacteria were isolated from all three arthropod Bacteria were isolated from all three arthropod speciesspecies

T Soy Agar T Soy Agar ((Periplaneta Periplaneta americanaamericana))

Isolated 5 speciesIsolated 5 species– UnderestimationUnderestimation– PsychotolerantPsychotolerant

Careful, they’re quick.

T Soy Agar T Soy Agar (Zophobas morio)(Zophobas morio)

Isolated 2 speciesIsolated 2 species

T Soy Agar T Soy Agar (Acheta (Acheta dometicus)dometicus)

Isolated 2 speciesIsolated 2 species

Populations and DiversityPopulations and Diversity

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10

Cri

cket

Cock

roach

My Data

Weight of gut # of Weight of gut # of speciesspecies– Cricket = 2mg 2Cricket = 2mg 2– Mealworm =54mg 2Mealworm =54mg 2– Cockroach =25mg >5Cockroach =25mg >5

Bacteria/Biomass ratios Bacteria/Biomass ratios confirmed the findings of confirmed the findings of Cazemier et al. and other Cazemier et al. and other studiesstudies

Mealw

orm

Species

B

acte

rial C

ou

nt

(

1x1

0 ^

5

cfu

/mg

)

Bacteria/Biomass

Biochemical TestsBiochemical Tests 1) Fermentation1) Fermentation

Glycolytic PathwayGlycolytic Pathway

host/bacteriahost/bacteria bacteriabacteria

Lactose Lactose (6 C) — —> (6 C) — —> LactateLactate (3 C) —> Pyruvate,Acetic Acid, Ethanol (3 C) —> Pyruvate,Acetic Acid, Ethanol

Phenol red broth Phenol red broth Lactate BrothLactate Broth

ResultsResults

Bacteria were isolated from all three arthropod Bacteria were isolated from all three arthropod speciesspecies

6 species fermented lactose6 species fermented lactose

Glycolytic PathwayGlycolytic Pathway

Lactose —> Lactate —> Lactose —> Lactate —> Pyruvate/Acetic/EthanolPyruvate/Acetic/Ethanol

CockroachCockroach– Species 1Species 1 no no – Species 2Species 2 proteolytic proteolytic– Species 3Species 3– Species 4Species 4 – Species 5Species 5

MealwormMealworm– Species 6Species 6– Species 7Species 7

CricketCricket– Species 8Species 8 – Species 9 proteolyticSpecies 9 proteolytic

Lactose FermentationLactose Fermentation

control

proteolytic

cricket mealworm cockroach

lactose fermenters

proteolytic

ResultsResults

Bacteria were isolated from all three arthropod Bacteria were isolated from all three arthropod speciesspecies

6 species fermented lactose6 species fermented lactose

All Bacteria reduced lactateAll Bacteria reduced lactate

Glycolytic PathwayGlycolytic Pathway

Lactose —> Lactate —> Lactose —> Lactate —> Pyruvate/Acetic/EthanolPyruvate/Acetic/Ethanol

CockroachCockroach– Species 1Species 1 no no – Species 2Species 2 proteolytic proteolytic– Species 3Species 3– Species 4Species 4 – Species 5Species 5

MealwormMealworm– Species 6Species 6– Species 7Species 7

CricketCricket– Species 8Species 8 – Species 9 proteolyticSpecies 9 proteolytic

Biochemical TestsBiochemical Tests 1) Fermentation1) Fermentation

2) Cellulose Degradation2) Cellulose Degradation bacteriabacteria

Cellulose —> Simple Sugars (6 C)Cellulose —> Simple Sugars (6 C)

Cellulose plate/brothCellulose plate/broth

Cellulose DegradationCellulose Degradation

Cellulose Cellulose tests tests

were inconclusive were inconclusive

ConclusionsConclusions

My study confirmed the presence of large My study confirmed the presence of large bacterial populations living within the gut of bacterial populations living within the gut of arthropodsarthropods

These bacteria exhibited the ability to ferment These bacteria exhibited the ability to ferment compounds, whose end-products may be used compounds, whose end-products may be used by the host for nutritionby the host for nutrition

Further testing would be needed to determine Further testing would be needed to determine cellulose-degrading capabilities cellulose-degrading capabilities

AcknowledgementsAcknowledgements

Thank YouThank You

– Professor RoseProfessor Rose– Professor SmithProfessor Smith– TonyTony