Inhibition of certain lactic acid bacteria by free and bound sulphur dioxide

Abstract

Growth of two heterofermentative lactic acid bacteria (Lactobacillus hilgardii and Leuconostoc nzesenteroides) isolated from wine, was inhibited in a medium to which sulphurous acid and an excess of acetaldehyde had been added. It was found that the bacteria rapidly attacked the aldehyde and liberated sufficient free sulphur dioxide to prevent further growth. A homofermentative bacterium (Lactobacillus arabinosus) consumed much less aldehyde than the two heterofermentative organisms, but nevertheless failed to grow in the presence of 100 p.p.m. of bound sulphur dioxide.The significance of these results in relation t o the malo-lactic fermentation in wines is discussed.

Production of SO2 Binding Compounds and SO2 by Saccharomyces during Alcoholic Fermentation and the Impact on Malolactic Fermentation

“…However, strong inhibition of MLF was still observed demonstrating that, in this case, a shift in the form of some of the bound SO 2 from acetaldehyde bound to pyruvic acid bound did not impact the inhibition of MLF. Because of this, MLF inhibition by bound SO 2 in the present study was caused by acetaldehyde bound SO 2 , a finding in agreement with Fornachon (1963). In contrast, Larsen et al (2003) and Hood (1983) suggested forms of bound SO 2 other than acetaldehyde bound SO 2 were responsible for MLF inhibition although no alternative forms were identified.…”

“…This is further evidence that bound SO 2 has an inhibitory action against O. oeni VFO as suggested by others (Fornachon, 1963;Hood 1983;Larsen et al, 2003;Osborne & Edwards, 2006). However, what has not been established is whether the form of bound SO 2 present is important and whether different forms of bound SO 2 are more or less toxic to O. oeni.…”

“…In wine, the bisulfite ion will react with carbonyl compounds such as acetaldehyde, forming adducts such as hydroxysulfonic acids. Although acetaldehyde binds most strongly with SO 2 , other carbonyl compounds found in wine, such as pyruvic acid and a-ketoglutaric acid, may also bind with SO 2 (Fornachon, 1963;Rankine & Pocock, 1969;Burroughs & Sparks, 1973a;Azevedo et al, 2007). While bound SO 2 is thought to have much weaker antimicrobial properties than free SO 2 (and in particular the molecular portion) (Eschenbruch, 1974;Hammond & Carr, 1976;Hinze & Holzer, 1986;Rose & Pilkington, 1989), a number of researchers have suggested that bound SO 2 may be more antimicrobial than previously believed, particularly towards bacteria (Hood, 1983;Larsen et al, 2003;Osborne & Edwards, 2006).…”

Effect of pH, Temperature and S02 Concentration on the Malo-Lactic Fermentation Abilities of Selected Bacteria and on Wine Colour

“…However, MLF is possible at S02 concentrations where bacterial growth has been stopped (Lafon-Lafourcade, 1975). Heterofermentative cocci appeared to be more sensitive to S02 than other malo-lactic bacteria (Fornachon, 1963;Carr, Davies & Sparks, 1976).…”

“…The inhibitory effect of bound S02 may be due to bacterial attack on the aldehydes, which would set S02 free (Fornachon, 1963). A decrease in pH shifts the equilibrium of the reactions sol-+ H+ ~ HS03-+ H+ ~ S02 + H10 in the direction of molecular S0 2 which as a more potent effect on bacterial growth than the two ionic forms (Carr, Davies & Sparks, 1976).…”