Physicochemical Factors in Growth

摘要: Some physicochemical factors affecting microbial growth are controlled by the constituents of culture medium (hydrogen ion activity, water osmotic pressure, and viscosity). Others external environment (temperature, oxygen, light, hydrostatic magnetic-field strength). This chapter addresses practical aspects application control factors. Continuous pH may be achieved automatic addition acid or base. The effects pressure on physiology metabolism bacteria discussed. A number Pseudomonas Bacillus species also exhibit a microaerophilic phenotype when growing in low-substrate media. oxidation-reduction (redox) potential (Eh ) provides useful scale for measuring degree anaerobiosis. motile that possess magnetite- greigite containing magnetosomes, e.g., Magnetospirillum (formerly Aquaspirillum) magnetotacticum, align with Earth geomagnetic field, which has strength about 1 G. As consequence, they show biased swimming behavior, both north-seeking south-seeking forms known. behavior been termed magnetotaxis is thought, part, to help these (many microaerophilic) orient toward aquatic sediments where dissolved-oxygen concentrations lower than surface waters.