Growth and metabolic features of lactic acid bacteria in media with hydrolysed fish viscera. An approach to bio-silage of fishing by-products.

The reparameterization of two classic growth models (the logistic and Gompertz equations), and the dynamic modification of the integrated form of the first of these, was applied to the description of the kinetics and metabolic behaviour of six strains of lactic acid bacteria in four media: three of these from visceral waste from fishing products, and one commercial medium. The descriptions obtained -always consistent models and statistically significant parameters- provided a wide range of reliable numerical values on notable characteristics of microbial growth and bioproductions, which allowed the assessment of the individual systems by direct comparison, and also the suggesting of the potentially most suitable groups (of species of fish and of bacteria) for bio-silage processes.

Proteases production by two Vibrio species on residuals marine media.

A comparative study was carried out on the growth and production of alkaline proteases by two Vibrio species using different marine peptones from fish viscera residues. The bacteria tested, Vibrio anguillarum and Vibrio splendidus, are producers of high levels of proteolytic enzymes which act as factors of virulence in fish cultures, causing high mortality rates. The kinetic assays and subsequent comparison with the parameters obtained from the adjustment to various mathematical models, highlighted the potential interest of the media formulated, for their possible production on an industrial scale, particularly the production of proteases by V. anguillarum growing in rainbow trout and squid peptones.