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251.
A. J.H. Pieterse 《African Journal of Aquatic Science》2013,38(1):77-79
SUMMARY The Coulter Counter has been employed with success to estimate the number and sizes of suspended particles in seawater. In the present study this method was applied to Wuras Dam, a turbid man made lake south of Bloemfontein. High concentrations of larger clay sized particles occur in the inflow water as well as in the water of the dam proper. Fractionation of particles between ca 1 and 2 pm in diameter have been achieved, and a higher concentration of small sized particles (ca 1 μm) occurred in the dam water while the concentration of the larger particles (1,69 to 2,03 μm) was lower. Surface area estimations were made for each size fraction. A considerable surface area (ca 163 m2 m?3) was associated with the investigated suspended particles in Wuras Dam. This might be of extreme importance for the physical, chemical and biological characteristics of the dam. The limnological importance of the suspended particles is briefly discussed. 相似文献
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Smid Eddy J Erkus Oylum Spus Maciej Wolkers-Rooijackers Judith CM Alexeeva Svetlana Kleerebezem Michiel 《Microbial cell factories》2014,13(1):1-9
This review describes the recent advances made in the studies of the microbial community of complex and undefined cheese starter cultures. We report on work related to the composition of the cultures at the level of genetic lineages, on the presence and activity of bacteriophages and on the population dynamics during cheese making and during starter culture propagation. Furthermore, the link between starter composition and starter functionality will be discussed. Finally, recent advances in predictive metabolic modelling of the multi-strain cultures will be discussed in the context of microbe-microbe interactions.
相似文献253.
Deryl J. Barlow W. L.J. van Rensburl A. J.H. Pieterse J. N. Eloff 《African Journal of Aquatic Science》2013,38(2):79-83
SUMMARY Microcystis aeruginosa toxic strain UV-006 stored a fixed amount of polyphosphate in spherical granules located in the centroplasm. Twenty four hours of phosphate starvation induced use of stored polyphosphate, manifested by reduction in granule numbers. Reintroduction of 2, 4 or 8 mg l?1 K2HPO4 resulted in redeposition of polyphosphate in a critical number of centroplasmic polyphosphate granules. Growth rate was unaffected by phosphate concentrations, although the final cell yield was slightly lower at 8 mg l ?1 Continued starvation decreased photosynthetic rate and growth ceased. Cells appeared senescent. Cyanophycin and polyglucoside reserves apparently increased in these cells, whilst thylakoids were reduced in number and reorientated away from. the cell wall and polyhedral bodies were lost. After the initial decrease, centroplasmic polyphosphate bodies increased to about half of the maximum numbers stored in cells grown in the presence of phosphate, suggesting that translocation of phosphorus from other areas in the phosphate-starved cell occurred. Two further polyphosphate deposition areas were observed. DNA fibrils may have represented nucleation sites for developing polyphosphate granules. Intrathylakoidal deposits were rare. 相似文献
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K J van Vliet G L Smit J J Pieterse H J Schoonbee J H Van Vuren 《Comparative biochemistry and physiology. A, Comparative physiology》1985,82(1):19-21
Blood coagulation in two freshwater fish species was investigated by thrombelastography. This indicated that the process in fish is similar to that of humans and mammals, involving the same three basic processes, i.e. extrinsic and/or intrinsic thromboplastin generation, the conversion of prothrombin in thrombin and the formation of fibrinogen to fibrin. Calcium is essential for these reactions to occur. 相似文献
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