Formation of Hydrogen Peroxide by Group N Streptococci and Its Effect on Their Growth and Metabolism

Abstract

The formation of hydrogen peroxide by group N streptococci was found to occur through the action of a reduced nicotinamide adenine dinucleotide (NADH) oxidase which catalyzed the oxidation of NADH by molecular oxygen. The enzyme was activated by flavine adenine dinucleotide. Whereas some of the hydrogen peroxide formed was removed through the action of an NADH peroxidase, sufficient accumulated in media to inhibit the growth, respiration, and viability of these organisms. The amount of hydrogen peroxide which accumulated varied among strains, and this variation could be related to differences in the properties of the NADH oxidase present.

Responses of lactic acid bacteria to oxygen

“…Work at this laboratory established that about half of 20 Group N streptococci [8] and several lactobacitli [32] were inhibited by HzO 2 accumulation during aerobic growth. Other reports clearly demonstrate that accumulation to auto-inhibitory levels during exposure to 02 is widespread, but not universal among LAB [4,7,27,33,34; J.B. Smart and T.D. Thomas, unpublished data).…”

“…The NADH:H202 oxidase (Table 1) was first reported in S. faecalis by Dolin [1,2] and its presence in many LAB has since been confirmed [3][4][5][6][7][8]. The enzyme is cytoplasmic, is rather unstable and has not been purified.…”

“…Accumulation of H202 in aerobic cultures in LAB results from a greater capacity to form H202 than to break it down. A flavoprotein NADH peroxidase (Table 1) first reported by Dolin [2,50] and which is widespread among LAB [3][4][5]12,14,47,51,52; J.B. Smart and T.D. Thomas, unpublished data] is probably mainly responsible for H202 breakdown.…”

“…Many of these bacteria have the genetic capacity to make products other than lactate from pyruvate, such as acetate, CO2, formate, ethanol, acetoin, diacetyl and 2,3-butanediol [see Figs. [2][3][4] and their accumulation can be demonstrated by varying the conditions of sugar utilisation. For example, several lactic streptococci accumulate substantial amounts of formate, ethanol and acetate and correspondingly less lactate when grown in glucose-or lactose-limited unaerated chemostat cultures, whereas with excess sugar the same cultures are homolactic.…”

Overview on sugar metabolism and its control in – The input from in vivo NMR

“…However, some L. lactis strains can benefit from the presence of oxygen and their growth is positively affected by low oxygen levels [159,160]. Sensitivity to aeration is extremely variable and strain dependent, and oxygen can partially or completely inhibit growth of some L. lactis strains [150,159,161]. The ability to grow and survive in the presence of oxygen has been related to the presence of flavin-type NADH oxidases, NADH peroxidase and superoxide dismutase [150,[159][160][161][162][163][164].…”