Three Rhizobiumjaponicum strains and two slow-growing cowpea-type Rhizobium strains were found to remain viable and able to rapidly nodulate their respective hosts after being stored in purified water at ambient temperatures for periods of 1 year and longer. Three fast-growing Rhizobium species did not remain viable under the same water storage conditions. After dilution of slow-growing Rhizobium strains with water to 103 to 105 cells ml-', the bacteria multiplied until the viable cell count reached levels of between 106 and 107 cells ml-1. The viable cell count subsequently remained fairly constant. When the rhizobia were diluted to 107 cells ml-1, they did not multiply, but full viability was maintained. If the rhizobia were washed and suspended at 109 cells ml-', viability slowly declined to 107 cells ml-' during 9 months of storage. Scanning electron microscopy showed that no major morphological changes took place during storage. Preservation of slow-growing rhizobia in water suspensions could provide a simple and inexpensive alternative to current methods for the preservation of rhizobia for legume inoculation.

No abstract

No abstract

Fermentation involves many complex biological processes, some of which can be difficult to monitor. In this study, aerosol measurement was explored as an additional technique for monitoring a batch aerobic fermentation process using Escherichia coli strain W3110. Using this technique, a small aerosol extraction flow from the fermentor was continuously dried in‐line and analyzed with an aerosol size spectrometer and an aerosol photometer, used to measure the size‐integrated aerosol concentration. The results of the measurements demonstrated that the bacterial growth rate and the aerosol number concentration changed in a similar fashion: the effluent aerosol number concentration increased during the exponential growth phase and subsequently decreased after the bacterial cell concentration had reached a stable level. This aerosol concentration increased sharply approximately 1 h after initiation of growth. Thus, this increase in aerosol concentration suggests that the release of aerosols changes as a function of the microbial product formation activity. The products may change the rheological properties of the liquid, especially if surface‐active compounds are produced. The increase in aerosol concentration corresponds to a decrease in the values of the measured surface tension during the same time frame. Furthermore, the aerosol size spectrometer and the photometer showed similar time traces of the effluent aerosols. The size distributions of the solid residues from the fermentation broth remained relatively constant, while the concentrations changed with the phase of fermentation. As the photometer is inexpensive, it appears promising as a convenient instrument for monitoring fermentation processes.

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report discusses testing that was performed for analyzing the alkali-silica reactivity of ULHS in cement slurries.

No abstract

No abstract

No abstract