SUMMARY. TWO polysaccharides produced concurrently by Lactococcus lactis subsp. cremoris strain LC330 have been identified. One had a high molecular mass (> 1 x 10 s Da) and was neutral. The second was smaller (~ 10000 Da), charged and had a high phosphorus content. Sugar composition also differed. In chemostat culture the neutral polj'saccharide was influenced by temperature and by nitrogen limitation. This polysaccharide was branched with terminal galactose moieties and contained galactose, glucose and glucosamine. The phosphopolysaccharide was more complex with glucose, rhamnose, galactose and glucosamine in an approximate ratio of 6:5:4:1.
Microbiological developments during industrial meat fermentations (salami), made with and without commercial starter cultures, were followed at two factories in Germany and Italy. In the German product microbial growth was evident only for the first 48 h, followed by a gradual decline in numbers of most micro-organisms. The pH fell from 5.8 to 4.8 in the 28 d required for production. In Italy a similar situation was seen, except that a second period of bacterial growth began around 15 d, coincident with the appearance of intentional surface mould growth which reversed the pH fall, the final pH being 6.2. The German starter culture was a mixture of Lactobacillus plantarum and Staphylococcus carnosus, whereas in Italy only Staph. carnosus was used. The strain of Lact. plantarum used did not grow in the German product whereas the Staph. carnosus grew well in both products to form a substantial proportion of the final microflora.
The effects of culture conditions on acyl lipid metabolism in the oleaginous yeastRhodotorula gracilis (CBS 3043) have been investigated. Growth ofR. gracilis under conditions of nitrogen‐limitation resulted in the accumulation of large quantities of triacylglycerols. Thin layer and gas chromatographic analysis of total lipid extracts revealed that the majority of this storage lipid was produced by stationary‐phase cells. In contrast, no such increase in triacylglycerol biosynthesis could be detected in carbon‐limited cells. Freeze‐fracture electron microscopy evidence supported these findings. Growth medium composition was found to have little effect on the relative abundance of the primary phospholipid classes present inR. gracilis. The acyl compositions of triacylglycerols were similarly unchanged by alterations in the composition of the growth medium. In contrast, the degree of unsaturation exhibited by the phospholipid fractions appeared to be particularly sensitive to this external parameter. Acyl quality of triacylglycerol pools extracted from nitrogen‐limited cells were observed to become increasingly saturated as cultures increased in age.Growth of nitrogen‐limited cells at a lower growth temperature was observed to have little effect on triacylglycerol accumulation. However, both triacylglycerol and phospholipid fractions extracted from these cultures were found to contain increased proportions of the polyunsaturated fatty acid, α‐linolenate.
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