Development of lysine overproducing streptococcus strain and its utilisation in the conservation of forages
1991
Joo, E. (Pannon Agricultural Univ., Mosonmagyarovar (Hungary). Fac. of Agronomy)
Having been screened more then 700 clones, the best one showed in lysine free broth after 72 hours of incubation at 30 C, a lysine overproduction of 78 microgram/ml. We called that strain LIZLAK. In our further experiment we have tested whether the lysine content of the media influences, the lysine overproduction of the strain LIZLAK. We could establish that the lysine content of the media till to a lysine amount of 50 microgram/ml does not influence the lysine secretion of the strain. Over that value, a slight inhibition can be observed. At the same time, the methionine content has been increased, too, by 18,1 microgram/ml in the lysine free broth. In the case of alfalfa silage, we could not detect any improvement in lysine content due to inoculation with LIZLAK. Therefore we left out that plant from the further evaluations. The results of analysis of maize grain and cabbage silages are given in the tables 2,3,5. The results indicate a successful enrichment in lysine content of the silages. It takes about 0,5 g lysine/kg dry matter. A smaller increase in methionine could be also observed. On the other hand, the lactic acid production of the LIZLAK mutant is less then that of the wild type Streptococcus lactis. There was no any other mentionable difference between the quality parameters of the treated and control silages. On the basis of that result, the use of lysine overproducing bacteria seems to be an economic way to increase the feeding value of grain maize silage (or cabbage) and to cut the relativ costs of inoculation by the additional lysine production.
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