Event Title

Microbial and Carbon Cycling Analysis of Leaf Litter in an Agricultural Landscape during the Decomposition of Varying Lignin Composition of Sorghum Bicolor

Location

CSU Ballroom

Start Date

18-4-2016 10:00 AM

End Date

18-4-2016 11:30 AM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Christopher Ruhland

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Second Mentor's Name

Timothy Secott

Second Mentor's Department

Biological Sciences

Second Mentor's College

Science, Engineering and Technology

Description

Sorghum bicolor is used as livestock forage because of its drought tolerance in agronomic settings but is difficult to digest due to its high lignin content. The brown-midrib (BMR) varieties of S.bicolor have mutations that result in reduced concentrations of lignin, a complex polymer that provides structural rigidity in plants. The objectives of this investigation were to examine differences in microbial communities during decomposition of four S.bicolor strains (wild-type, bmr-6, bmr-12 and bmr-6-12) by identifying carbon substrates used during catabolism, and to test the decomposition rate of bmr varieties relative to their wild type counterparts. S.bicolor litter from all types were collected from senescing litter and placed in bags in a fallow field. We examined changes in mass, cellulose, hemicellulose, and lignin with a fiber analyzer. Changes in microbial communities were measured by examining carbon substrate utilization with BIOLOG plates (community level physiologic profiling; CLPP). After five months, no differences in decomposition were observed among strains. CLPP initially indicated microbial communities associated with the bmr-6-12 and wild type strains were significantly different. However, these differences diminished over time, indicating the lignin content had little effect on microbial consortium. Microbial communities in surrounding soil remained different. Communities associated with the wild-type changed little, indicating microbes associated with the wild type were different from those of the soil. These changes contrasted what was observed for bmr-6-12 and help illuminate the role of microorganisms in nutrient cycling and their subsequent abilities to break down lignin.

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Apr 18th, 10:00 AM Apr 18th, 11:30 AM

Microbial and Carbon Cycling Analysis of Leaf Litter in an Agricultural Landscape during the Decomposition of Varying Lignin Composition of Sorghum Bicolor

CSU Ballroom

Sorghum bicolor is used as livestock forage because of its drought tolerance in agronomic settings but is difficult to digest due to its high lignin content. The brown-midrib (BMR) varieties of S.bicolor have mutations that result in reduced concentrations of lignin, a complex polymer that provides structural rigidity in plants. The objectives of this investigation were to examine differences in microbial communities during decomposition of four S.bicolor strains (wild-type, bmr-6, bmr-12 and bmr-6-12) by identifying carbon substrates used during catabolism, and to test the decomposition rate of bmr varieties relative to their wild type counterparts. S.bicolor litter from all types were collected from senescing litter and placed in bags in a fallow field. We examined changes in mass, cellulose, hemicellulose, and lignin with a fiber analyzer. Changes in microbial communities were measured by examining carbon substrate utilization with BIOLOG plates (community level physiologic profiling; CLPP). After five months, no differences in decomposition were observed among strains. CLPP initially indicated microbial communities associated with the bmr-6-12 and wild type strains were significantly different. However, these differences diminished over time, indicating the lignin content had little effect on microbial consortium. Microbial communities in surrounding soil remained different. Communities associated with the wild-type changed little, indicating microbes associated with the wild type were different from those of the soil. These changes contrasted what was observed for bmr-6-12 and help illuminate the role of microorganisms in nutrient cycling and their subsequent abilities to break down lignin.

Recommended Citation

Tiry, Celsey. "Microbial and Carbon Cycling Analysis of Leaf Litter in an Agricultural Landscape during the Decomposition of Varying Lignin Composition of Sorghum Bicolor." Undergraduate Research Symposium, Mankato, MN, April 18, 2016.
http://cornerstone.lib.mnsu.edu/urs/2016/poster-session-A/9