Bacteria chemical mutagenesis

Mutants impaired in the synthesis and accumulation of PHAs have been obtained from conventional chemical mutagenesis or transposon mutagenesis from many bacteria. Mutant PHB4 from R. eutropha strain H16 [130] and mutant GpP104 from P. putida strain KT2442 [36] are most probably those mutants which were mostly used, although the genotypes of these mutants were never analyzed. 

The introduction of techniques for mutagenesis by UV irradiation or by the use of chemicals considerably extended the applications of microbial studies to nutrition (Davis, 1954-1955). Auxotrophic mutants were produced with nutrient dependencies not shown in the untreated parental strains (Beadle and Tatum, 1940). The fortuitous discovery of penicillin by Fleming and its successful use in the treatment of infections (Florey) promoted exhaustive research into its mode of action. Eventually it was established that penicillin prevented the proliferation of gram-positive bacteria by blocking the synthesis of their cell walls... 

Other, more sensitive, tests have been suggested for the evaluation of potential carcinogenic risk of exposure to chemicals. These include the bacterial mutagenesis test devised by Dr. Bruce Ames ( ). This test has been applied to many of the amines listed in Table 1, both alone and after reaction with nitrite in weakly acid solution, followed by neutralization and application to the bacteria. In Table 3 are given the results of a number of such tests, together with comparison of the results of chronic... 

At the present time such non-haemolytic and hyaluronidase-negative strains are usually obtained by non-direct chemical and UF-induced mutagenesis, followed by selection or cloning of the hyaluronidase gene in order to transform Streptococcus sp. into non-pathogenic bacteria [33]. Of all the hyaluronan producers, the most appropriate strain is streptococcus of the group C, that is Streptococcus equi because it produces the highest yield of HA [30]. 

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