RESUMO
This study examined the possibility of preserving Beijerinckia cultures by encapsulation using a spray drier, for use in biotechnological processes in the production of biopolymers. An adequate choice of the wall (coating) material is one of the factors that will determine the degree of cell survival and the maintenance of fermentative activity in the encapsulated inoculum. Malt dextrin, dehydrated glucose syrups, modified starch, and acacia (gum arabic) were used as wall materials. The results showed that spray-dried Beijerinckia encapsulated in malt dextrin, stored for 2 mo, and inoculated into sterile must after rehydration presented the greatest stability with respect to fermentative activity, although the glucose-encapsulated cells showed the highest percentage of viability during spray drying and during the storage period.
Assuntos
Beijerinckiaceae/crescimento & desenvolvimento , Dextrinas/química , Microbiologia Industrial/métodos , Preservação Biológica/métodos , Beijerinckiaceae/metabolismo , Desidratação , Fermentação , Glucose/química , Goma Arábica/químicaRESUMO
AIMS: This study aims at evaluating the ability of Beijerinckia derxii, a free-living nitrogen (N)-fixing bacterium frequently isolated from tropical soils, to release certain plant growth regulators [indoleacetic acid (IAA), ethylene, polyamines] and amino acids into the growth medium. METHODS AND RESULTS: The production of those substances was compared using both cultures in which nitrogenase was active (N-free medium) and cultures in which nitrogenase was repressed (combined-N cultures). Those cultures were grown under agitation and in absence of agitation. Total IAA production was higher in agitated, N-free cultures but specific production was greater in combined-N cultures under agitation. Putrescine and spermidine were detected under all conditions tested. Ethylene was produced in both N-free and combined-N cultures. A greatest diversity of amino acids was released in N-free cultures. CONCLUSIONS: There was no inhibition of the production of the analysed substances under conditions where nitrogenase was inactive. SIGNIFICANCE AND IMPACT OF THE STUDY: Beijerinckia derxii is potentially a producer of plant-active substances; its presence in the natural environment suggests that this bacterium may contribute to the development of other living organisms.