Morphological changes in putrefactive anaerobe 3679 (Clostridium sporogenes) induced by sorbate, hydrochloric acid, and nitrite

Abstract

Putrefactive anaerobe 3679 (Clostridium sporogenes), a gram-positive bacterium, was examined by light and electron microscopy during normal growth and in a medium containing sorbate (50 mM, pH 6.5), hydrochloric acid (pH of medium adjusted from 7 to 5 with HCl), or nitrite (1 mM, pH 7). During the early exponential growth phase, untreated cells were filamentous and nonseptate, but became septate later and divided when the culture entered the stationary phase. Untreated short and filamentous cells had a double-layered cell wall. Sorbate-treated cells were usually filamentous and nonseptate, but with distorted shapes characterized by numerous bends and bulges. Septation, when present, resulted in minicells. The inner cell wall appeared to be thickened and the outer wall was absent in many areas. Acid-treated cells were similar to sorbate-treated cells but contained septa. Considerable cellular debris was present in the suspension. Nitrite-treated cells were also filamentous, bent, and bulged but the cell wall appeared normal. Considerable cellular debris was also present in suspensions of nitrite-treated cells. Changes in morphology are discussed in relation to possible mechanisms of cell growth regulation and the inhibitory action of sorbate, acid, and nitrite.

Study of the combined effect of electro-activated solutions and heat treatment on the destruction of spores of Clostridium sporogenes and Geobacillus stearothermophilus in model solution and vegetable puree

“…In our work we found a reduction of ≥6 logs CFU/ml of C. sporogenes concluding that the mode of action involved damaging inner and outer bacterial membranes resulting in necrosis thereby killing E. coli O157: H7 [42]. A similar result was found in the work of Ronning and Frank (1989) where they microscopically observed the growth phases of C. sporogenes injured by sorbate, hydrochloric acid and nitrite in the medium [43]. Inhibitory action of sorbate and hydrochloric acid was found similar; the cells were with distorted shapes M A N U S C R I P T…”

“…Furthermore, cell wall appeared to be thickened and the outer wall was absent in many areas [43]. Marais and Brozel (2006) concluded that different reactive chemical species (e.g.…”