The growth of compact and diffuse variants of Staphylococcus aureus in bovine mastitic and normal whey

Comparative growth of trichoderma strains in different nutritional sources, using bioscreen c automated system

Trichoderma is one of the fungi genera that produce important metabolites for industry. The growth of these organisms is a consequence of the nutritional sources used as also of the physical conditions employed to cultivate them. In this work, the automated Bioscreen C system was used to evaluate the influence of different nutritional sources on the growth of Trichoderma strains (T. hamatum, T. harzianum, T. viride, and T. longibrachiatum) isolated from the soil in the Juréia-Itatins Ecological Station (JIES), São Paulo State - Brazil. The cultures were grown in liquid culture media containing different carbon- (2%; w/v) and nitrogen (1%; w/v) sources at 28ºC, pH 6.5, and agitated at 150 rpm for 72 h. The results showed, as expected, that glucose is superior to sucrose as a growth-stimulating carbon source in the Trichoderma strains studied, while yeast extract and tryptone were good growth-stimulating nitrogen sources in the cultivation of T. hamatum and T. harzianum.

Growth characteristics of Staphylococcus aureus and Escherichia coli in whey from sequentially infected milk

The growth of Staphylococcus aureus and Escherichia coli was followed in bovine whey samples which had been prepared from milk previously incubated with cultures of S. aureus or E. coli. Staphylococcal strains were divided into 2 groups according to their ability to form compact or diffuse colonies on serum soft agar, which is related to the absence or presence of capsule respectively. The growth of compact staphylococci was dependent on the bulk tank milk used whereas diffuse colony forming staphylococci grew equally well in all bulk milk, also in all inoculated milk. The growth of E. coli was markedly enhanced in whey samples prepared from milk preincubated with staphylococci. However, clear growth inhibition was seen with E. coli and S. aureus strains when grown in whey prepared from milk preincubated with E. coli. Results indicate that the growth promotion of pathogens due to compositional changes in milk are of importance during the course of infection because the growth pattern on staphylococci is dependent on these compositional changes. The growth-inhibitory effects caused by E. coli may explain difficulties in isolating this organism.