Regulation of Enzymatic Insect Breakdown in Pitcher Plants
Mentor 1
Dr. Erica Young
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
Carnivorous pitcher plants capture insect prey, which is broken down to release nutrients for plant uptake, compensating for poor nutrient supply from soils. Unlike some carnivorous pants, pitcher plants make no digestive enzymes of their own. They therefore depend on a microbial community in pitcher fluid to produce hydrolytic enzymes including chitinase, which breaks down the chitin in insect exoskeletons. This research aimed to examine the regulation of chitinase activity in pitcher microbial communities in response to additions of insect prey and supply of alternative nitrogen (N) and carbon (C) substrates. Pitchers maintained in the greenhouse were enriched with Drosophila fruit flies, glucose as a C source, or glutamine as a C and N source. Chitinase and protease enzyme activity was measured in pitcher fluid samples collected at 0, 6, 12, 24, 48, and 96 hours after additions using fluorometric assays. Samples were also collected for bacterial abundance measurements using epifluorescence microscopy. To determine the contribution of chitinase activity from flies, rather than the bacteria, whole and ground flies were added to sterile water and chitinase activity assayed over 2 weeks. Fluorometric assay data was plotted and change over time analyzed by regression to obtain rates of hydrolysis, proportional to enzyme activity. Preliminary results indicate that enzyme activity was quite variable between pitchers, even with the same treatment. Chitinase activity peaked 12-24 hours after addition of nutrients and/or flies, and declined in all treatments by 48 hours. High activities were observed with all 3 pitcher additions, and glutamine- or glucose-only additions also showed high chitinase activity. These results suggest that supply of alternative C and N substrates for bacteria did not suppress chitinase activity targeted towards fly degradation. Results also suggest that some chitinase activity measured in pitchers may be derived from fly carcasses, not from resident bacteria.
Regulation of Enzymatic Insect Breakdown in Pitcher Plants
Union Wisconsin Room
Carnivorous pitcher plants capture insect prey, which is broken down to release nutrients for plant uptake, compensating for poor nutrient supply from soils. Unlike some carnivorous pants, pitcher plants make no digestive enzymes of their own. They therefore depend on a microbial community in pitcher fluid to produce hydrolytic enzymes including chitinase, which breaks down the chitin in insect exoskeletons. This research aimed to examine the regulation of chitinase activity in pitcher microbial communities in response to additions of insect prey and supply of alternative nitrogen (N) and carbon (C) substrates. Pitchers maintained in the greenhouse were enriched with Drosophila fruit flies, glucose as a C source, or glutamine as a C and N source. Chitinase and protease enzyme activity was measured in pitcher fluid samples collected at 0, 6, 12, 24, 48, and 96 hours after additions using fluorometric assays. Samples were also collected for bacterial abundance measurements using epifluorescence microscopy. To determine the contribution of chitinase activity from flies, rather than the bacteria, whole and ground flies were added to sterile water and chitinase activity assayed over 2 weeks. Fluorometric assay data was plotted and change over time analyzed by regression to obtain rates of hydrolysis, proportional to enzyme activity. Preliminary results indicate that enzyme activity was quite variable between pitchers, even with the same treatment. Chitinase activity peaked 12-24 hours after addition of nutrients and/or flies, and declined in all treatments by 48 hours. High activities were observed with all 3 pitcher additions, and glutamine- or glucose-only additions also showed high chitinase activity. These results suggest that supply of alternative C and N substrates for bacteria did not suppress chitinase activity targeted towards fly degradation. Results also suggest that some chitinase activity measured in pitchers may be derived from fly carcasses, not from resident bacteria.
