Effect of hydrolysable and condensed tannins on growth, morphology and metabolism of Streptococcus gallolyticus (S. caprinus) and Streptococcus bovis

Abstract

Streptococcus gallolyticus (S. caprinus) was resistant in vitro to at least 7 % (w/v) tannic acid and 4 % (w/v) acacia condensed tannin, levels 10-fold greater than those tolerated by S. bovis. Growth of S. gallolyticus in liquid medium was characterized by a lag period which increased, and a growth rate which decreased, with increasing tannin concentration. S. gallolyticus was also more tolerant to the presence of simple phenolic acid monomers than was S. bovis, but the lag period was still concentration dependent. Gallate decarboxylase activity in S. gallolyticus was elevated in the presence of tannic acid or gallic acid but not with other phenolic acids. Scanning electron microscopic analysis showed that both the size and shape of S. gallolyticus and S. bovis changed in response to tannin but only S. gallolyticus was surrounded by an extracellular polysaccharide matrix which accumulated in a tannin-concentration-dependent fashion. Washing of the cells to remove extracellular polysaccharide increased the lag period of S. gallolyticus in the presence of 1 % (w/v) tannic acid from 4 h to 6 h. In contrast, increasing extracellular polysaccharide synthesis in S. bovis did not increase its tolerance to tannic acid. These data demonstrate that S. gallolyticus has developed a number of mechanisms to reduce the potential effect of tannins on cell growth, and that these mechanisms provide the organism with a selective advantage over S. bovis when grown in the presence of tannins.

Tannin-tolerant bacteria from crossbred Holstein x Zebu cows

“…Regarding fermentation patterns, three divisions for S. bovis are described in literature (Ruoff et al, 1989); among these, the group biotype I is able to ferment mannitol, as isolate 7 from the present study. Tannin tolerance has been described for the genus ) acacia condensed tannin, levels 10-fold greater than those tolerated by S. bovis (O'Donovan & Brooker, 2001). Similarly, Rusniok et al (2010) described the ability of this species to adapt to the presence of tannins in the rumen, due to its capacity to use a broad range of carbohydrates, as found in the present study (Table 1), especially those present in the plant cell wall, and to express several hydrolytic enzymes, including tannases and other phenolic compounds decarboxylases that should contribute to the detoxification of the digestive tract.…”

“…Similarly, Khiaosa-Ard et al (2009) observed that treatments of feed with condensed tannins reduced ruminal fiber and crude protein degradation. However, effectively using feedstuff is still possible, due to the complex microbiota found in the gastro-intestinal tract, whose composition is mainly determined by the available diet (O'Donovan & Brooker, 2001;Ammar et al, 2009;Khiaosa-Ard, 2009). …”

Semi arid browse forages: Their antinutritive substances and in sacco neutral detergent fibre and organic matter degradability

“…However, effects are not the same for all CT as they depend upon its chemical structure [24]. Several ruminal microorganisms have been identified that can tolerat relatively high concentrations of both hydrolysable and condensed tannins (CTs) [34]. However, the mechanism for this tolerance has not been completely elucidated.…”

The role of condensed tannins in ruminant animal production: advances, limitations and future directions

“…are generally HT rather than CT. However, S. gallolyticus also demonstrates resistance to Acacia CT (< 4%) in vitro, whereas S. bovis is inhibited at >0.5% (O'Donovan and Brooker, 2001). Whether S. gallolyticus or other rumen microbes have the ability to degrade CT in the rumen is unclear.…”