Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Interpretive Summary: Active composts have a high level of microbial activity, and a rapidly changing microbial community. Tracking individual microbe groups or changes in the community requires a technique that is sensitive and independent of incubations, which themselves will allow the community to change. Phospholipids are present in all living cells. In microorganisms, the phospholipid makeup varies among species and also within species under differing growing conditions. Phospholipids were extracted from compost samples at initial, middle, and final stages of compost development. Changes in the populations of certain groups of microbes, such as bacteria, fungi, or thermophiles (heat-loving microbes), could then be identified. In these compost piles, total bacteria declined over time, although thermophilic organisms increased. Limitations of this and related techniques are discussed. Another method of analyzing a microbial community is by testing its ability to utilize specific compounds as sources of carbon. Microbes present in more mature compost were better able to utilize sugars found in plant material. This research will impact scientists who study compost and its microbial populations. Extraction and analysis of phospholipids is an indicator of the living population.
Technical Abstract: Composts were sampled three times during an 8-week development period and tested for phospholipid fatty acid (PLFA) contents and carbon source utilization. The proportion of the community made up by bacteria, particularly aerobes, (as determined by PLFA's) decreased during compost development. Indicators of thermophiles increased from the initial sampling, even though temperature declined. Several PLFA indicators gave differing results about populations of anaerobic organisms, so that this group could not be reliably tracked. Ability of the compost microbial inhabitants to utilize sucrose, galactose, and fructose, sugars common to plant material, increased during compost development; utilization of trehalose, uncommon in plant material, decreased.