Environmental stress and micro-organisms. Leavening baked foods

anglais. This is a report on the ability of lactic acid bacteria (LAB), given that they are microflora of food products, to cohabit and overcome certain phases of stress of varying nature. The types of stress in question are stress caused by acidity, and stress of a thermal and osmotic nature, which require, in order for them to be overcome, protein synthesis (as of new or significantly changed in the levels of protein expression). Even LABs from oven-leavened products are physiologically adapt in this special manner. Conditions for overcoming critical phases, in the sense mentioned, by the LABs, have been researched in this paper, in order to understand the relative systems of response that are considered to be useful for favouring the use of this natural starter (acid yeast, natural yeast, leaven, sourdough). Therefore, using experimental systems, answers that were useful for understanding certain mechanisms of resistance were illustrated. This is something which, as far as our knowledge on the subject goes, had not been previously pointed out

italien. E' stato riferito sull'attitudine dei batteri lattici (LAB), in quanto microflora dei prodotti alimentari, a convivere e superare alcune fasi di stress di differente natura. Si tratta di stress da acidita', di natura termica e osmotica, i quali richiedono, per il loro superamento, sintesi proteiche (ex novo o di significativo cambiamento nei livelli di espressione proteica). Anche i LAB dei prodotti lievitati da forno mettono in atto questa particolare fisiologia adattativa. Le condizioni di superamento delle fasi critiche, in tal senso indicate, da parte dei LAB, sono state ricercate in questo studio per conoscere i relativi sistemi di risposta, ritenuti utili per favorire l'uso di questo starter naturale (lievito acido, lievito naturale, levains, sourdough). Pertanto, attraverso sistemi sperimentali si sono evidenziate risposte utili a comprendere certi meccanismi di resistenza, cio' che, secondo le nostre conoscenze sull'argomento, non era stato messo in evidenza in precedenza