The role of the motility of Methylobacterium in bacterial interactions in drinking water

Bacterial motility is one important factor that affects biofilm formation. In drinking water there are key bacteria in aggregation, whose biology acts to enhance the formation of biofilms. However, it is unclear whether the motility of these key bacteria is an important factor for the interactions between bacteria in drinking water, and, subsequently, in the formation of aggregates, which are precursors to biofilms. Thus, the role of the motility of one of these key bacteria, the Methylobacterium strain DSM 18358, was investigated in the interactions between bacteria in drinking water. The motility of pure Methylobacterium colonies was initially explored; if it was affected by the viscosity of substrate, the temperature, the available energy and the type of substrate. Furthermore, the role of Methylobacterium in the interactions between mixed drinking water bacteria was investigated under the mostly favourable conditions for the motility of Methylobacterium identified before. Overall, the motility of Methylobacterium was found to play a key role in the communication and interactions between bacteria in drinking water. Understanding the role of the motility of key bacteria in drinking water might be useful for the water industry as a potential tool to control the formation of biofilms in drinking water pipes

A keystone Methylobacterium strain in biofilm formation in drinking water

The structure of biofilms in drinking water systems is influenced by the interplay between biological and physical processes. Bacterial aggregates in bulk fluid are important in seeding biofilm formation on surfaces. In simple pure and co-cultures, certain bacteria, including Methylobacterium, are implicated in the formation of aggregates. However, it is unclear whether they help to form aggregates in complex mixed bacterial communities. Furthermore, different flow regimes could affect the formation and destination of aggregates. In this study, real drinking water mixed microbial communities were inoculated with the Methylobacterium strain DSM 18358. The propensity of Methylobacterium to promote aggregation was monitored under both stagnant and flow conditions. Under stagnant conditions, Methylobacterium enhanced bacterial aggregation even when it was inoculated in drinking water at 1% relative abundance. Laminar and turbulent flows were developed in a rotating annular reactor. Methylobacterium was found to promote a higher degree of aggregation in turbulent than laminar flow. Finally, fluorescence in situ hybridisation images revealed that Methylobacterium aggregates had distinct spatial structures under the different flow conditions. Overall, Methylobacterium was found to be a key strain in the formation of aggregates in bulk water and subsequently in the formation of biofilms on surfaces

Productivity of Florida Springs: Second semi-annual report to the Biology Division, Office of Naval Research progress from February 1, 1953 to June 30, 1953

During this second six months emphasis has been laid on developing a complete understanding of the metabolism of the Silver Springs ecosystem as an example of a community apparently in a steady state. Variation in phosphates, uptake of nitrates, and importance of boron have been estimated. Fluctuation of some major elements has been estimated. Examination of stomach contents has permitted trophic classifications of dominant species and the standing crops have been estimated for these species by number and by dry weight. From these a pyramid of mass has been constructed. Special attention has been paid to bacteria using 3 methods for comparison of Silver Springs with lakes and estimation of the standing crop. The oxygen gradient method has been repeated at half hourly intervals. A carbon-dioxide gradient method has also been used to check the oxygen and to obtain a photosynthetic quotient. Black and light Bell jar experiments have been initiated to obtain checks on the other production measurement and to obtain a community respiration rate. An approximate balance has resulted from estimates of production , respiration , and downstream loss. A flow rate diagram has been constructed to clarify definitions of efficiency and their relationship to a steady state system. Mr. Sloan has statistically verified the increase of insect number and variety away from the boils and demonstrated the reliability of quantitative dipping for aquatic insects. Plans for the third half year include detained and comparative study of the dominant algae and further estimates of rates of growth of all community components. (29pp.

Productivity of Florida Springs: first semi-annual report to Biology Division, Office of Naval Research, progress from June 1, 1952 to January 31, 1953

Work has begun on studying the factors responsible for productivity in the Florida springs, which are nearly constant temperature, constant chemical, steady state giant laboratories. Progress has been made on five aspects: qualitative description, quantitative description, completion of knowledge of chemical factors, measurement of productivity , development of productivity theory. Measurement of the primary productivity in Silver Springs and Green Cove Springs by two new methods: the raising of organisms in cages, and the measurement of night & day differences in oxygen downstream agree roughly. Production in these springs is greater than previous production figures reported for marine, fresh water, and land areas. Instantaneous measures of production show large variations with season, time of day, cloud cover. Production estimates range from 11,000 lbs per acre per year to 70,000 lbs. glucose per acre per year during daylight hours. Essential stability of the springs environment has been shown with respect to temperature, phosphorus, and plant cover. A correlation of species number with lack of stability has been shown with insects. Quantitative studies have shown very large plant base to pyramids of mass. Correlation of marine invasion with chlorinity has been shown. The essential aspects of pH regulated phosphorus geochemistry in Florida have been outlined. Some theoretical ideas on productivity have been evolved. Mapping of sessile organisms in springs and taxonomic identification of dominants are half completed. Plans for second six months include measurement of herbivore and carnivore production rates and completion of food chain efficiency determinations in Silver Springs as a preparation for subsequent comparisons between springs. (34pp.