Populations and Softening Enzyme Activity of Filamentous Fungi on Flowers, Ovaries, and Fruit of Pickling Cucumbers

Although investigations have dealt with softening of brined cucumbers since 1899 (Aderhold), the studies have been primarily concernied with proving the bac- terial theory of spoilage.Much effort has been directed toward implicating the aerobic bacilli as the responsible agents (Kossowicz, 1908; LeFevre, 1919; Fabian and Johnson, 1938; Faville and Fabian, 1949; Demain and Fabian, 1950, Unpublished Experiments; and Vaughn et al., 1954).The nature of the acid fermentation of cucumbers presents three important obstacles to serious consideration of the much-studied aerobic bacillus theory of softening spoilage: (1) the salt content of the fermenting brines; (2) the acidic condition of the brine aind accom- painying drop in pH resulting from early and rapid development of the lactic acid bacteria; and (3) the low oxygen tension of the brine attested to by excellent grow-th of the microaerophilic, lactic acid bacteria.SucK conditions wrould indeed be highly restrictive if niot wholly inhibitive for growth by aerobic, sporeform- ing bacteria of the genius Bacillus.Thus it is niot sur- prising that populations for these organisms have niot beeii demonstrated in cucumber fermentations brined under conditions typical of the industry.Early brining studies (UInpublished) by Etchells anid Jones (1940), conducted with replicated 45-gallon bar- rel lots at a commercial pickle plant in easterni North Carolina, confirmed the above conclusion that cucumber fermentations offer a rather unfavorable environment for development of aerobic bacilli.Heavy inocula of washed cells of young cultures of Bacillus mesentericus fuiscas (Bacillus stibtilis) failed to develop when added to cucumber fermentations at the outset, and the cured brine-stock showed no loss of firmness over uninoculated controls.Furthermore, in other experiments, broth fil- trates from the above organism, when added to cucum- ber fermentations at the start, did not cause softening ' One of the laboratories of the Southern Utilization Re- search and Development D)ivision, Agriculttural Research Serv- ice, U. S. Department of Agrictultture.