Chemical and Biological Assays to Evaluate Bacterial Inhibition by Tannins

Tannin-tolerant bacteria from crossbred Holstein x Zebu cows

“…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. Nelson et al (1997) also observed that Streptococcus was able to tolerate tannin. Therefore, the different fermentation patterns found among isolates 7 and 37, in the present study, may indicate a new species not previously described in literature.…”

“…To increase the number of tannin-tolerant strains, 2 or 3 g L -1 of tannin extract were added. The tubes were incubated at 39 o C for three days (Nelson et al, 1997). Isolated colonies were picked under CO 2 and transferred into tubes containing glucose medium, and incubated at 39 o C overnight.…”

“…Bacterial isolates were characterized according to Nelson et al (1997) and Odenyo et al (2001), with some modifications, by Gram staining and motility (fresh aliquots diluted into ADS solution) through examination on phase-contrast microscopy (Leitz Laborlux, Leica Microsystems, Wetzlar, Germany). The growth rate of each isolate was determined in glucose medium, and the growth measured as a direct proportion to the increase in light absorbance at 600 nm (OD 600 nm) every hour for eight hours.…”

Efeito dos taninos condensados de forrageiras nativas do semi-árido nordestino sobre o crescimento e atividade celulolítica de Ruminococcus flavefaciens FD1

“…A exemplo de Fibrobacter succinogenes e Ruminococcus albus (Bae et al, 1993;Nelson et al, 1997), FD1 foi fortemente inibida pela presença de taninos condensados solúveis no meio. A concentração de 50µg/ml de taninos condensados das três espécies estudadas foi capaz de reduzir a atividade da endoglucanase em, pelo menos, 44,5%.…”

“…Essas plantas, a exemplo da maioria das leguminosas tropicais, A presença de taninos na dieta diminui a digestibilidade dos carboidratos fibrosos, levando a decréscimo na produção de ácidos graxos voláteis, de gases e do valor energético dos alimentos (Kumar e Singh, 1984). Esses efeitos são atribuídos às ligações dos taninos solúveis com componentes da parede celular, tendo como resultado complexos indigestíveis ou inacessíveis às enzimas bacterianas (CanoPoloche, 1993), à redução da atividade enzimática, com inativação de importantes enzimas microbianas, ou ainda a uma modificação da microflora, devido à ação bacteriostática ou bactericida do tanino (Kumar e Vaithiyanathan, 1990;Nelson et al, 1997;Mcsweeney et al, 2001). …”