Diversity of bacterial morphologies

The rich nutrient supply, moderate temperatures during transportation and storage of mineral slurry dispersions, as well as a neutral to slightly alkaline pH (7 10), provide an environmental spectrum of conditions for a large number of microorganisms to develop and thrive. 

Photo 4 Identification of microorganisms found to occur in mineral dispersions. 

Photo 3 Bacterial diversity in a CaCOs slurry sample from France lOOx / light microscopy with phase contrast. 

Photo 4 This gel shows RISA products, prepared by PCR amplification of the 16s-23s spacer region on the rDNA operon of several CaCOs slurry isolates. The number of bands corresponds to the number of rDNA operons inherent to each species while the size and sequence of each spacer region is species specific. 

Depending on the nutrient supply, some species can be favoured. Similarly, in certain cases often found in mineral slurries, Methanotrophs and Methylotrophs can be favoured not only due to original nutrient sources but also in respect to the biocides used. A wide variety of bacteria are known that can grow on methanol, methylamine, or formate, and, in the case of Methanotrophs, also on methane. If, therefore, pure formaldehyde donors are used as biocide it cannot be ruled out that bacteria of these genera will accumulate over a certain period of time. This is just one example of how the spectrum of bacteria in relation to nutrient before and during preservation must be considered and not just the original dominant contamination. 

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