Some invasive species threaten native species because they possess traits to which natives are evolutionarily naïve. In Australia, many predators have been severely impacted by the introduction of cane toads, which produce toxins that native species have never encountered. Torresian crows, however, have been observed consuming cane toads safely by avoiding their toxin glands, suggesting learned behavioural adaptations. To inve...

The Kenya long‐term exclosure experiment (KLEE) was established in 1995 in semi‐arid savanna rangeland to examine the separate and combined effects of livestock, wildlife and megaherbivores on their shared environment. The long‐term nature of this experiment has allowed us to measure these effects and address questions of stability and resilience in the context of multiple drought‐rainy cycles. Here we outline lessons learned...

Summary Type IV pili (T4P) are bacterial surface‐exposed appendages that have been extensively studied in Gram‐negative pathogenic bacteria. Despite recent sequencing efforts, little is known regarding these structures in non‐pathogenic anaerobic Gram‐positive species, particularly commensals of the mammalian gut. Early studies revealed that T4P in two ruminal Gram‐positive species are associated with growth on cellulose, sugg...

Summary Interspecies cross‐feeding is a fundamental factor in anaerobic microbial communities. In the human colon, formate is produced by many bacterial species but is normally detected only at low concentrations. Ruminococcus bromii produces formate, ethanol and acetate in approximately equal molar proportions in pure culture on RUM‐RS medium with 0.2% Novelose resistant starch (RS3) as energy source. Batch co‐culturing on st...

Summary Ruminococcus bromii is a dominant member of the human colonic microbiota that plays a ‘keystone’ role in degrading dietary resistant starch. Recent evidence from one strain has uncovered a unique cell surface ‘amylosome’ complex that organizes starch‐degrading enzymes. New genome analysis presented here reveals further features of this complex and shows remarkable conservation of amylosome components between human colo...

Summary Ruminococcus champanellensis is a keystone species in the human gut that produces an intricate cellulosome system of various architectures. A variety of cellulosomal enzymes have been identified, which exhibit a range of hydrolytic activities on lignocellulosic substrates. We describe herein a unique R. champanellensis scaffoldin, ScaK, which is expressed during growth on cellobiose and comprises a cohesin module and a...

Summary Cereal fibres such as wheat bran are considered to offer human health benefits via their impact on the intestinal microbiota. We show here by 16S rRNA gene‐based community analysis that providing amylase‐pretreated wheat bran as the sole added energy source to human intestinal microbial communities in anaerobic fermentors leads to the selective and progressive enrichment of a small number of bacterial species. In parti...

Summary R uminococcus champanellensis is considered a keystone species in the human gut that degrades microcrystalline cellulose efficiently and contains the genetic elements necessary for cellulosome production. The basic elements of its cellulosome architecture, mainly cohesin and dockerin modules from scaffoldins and enzyme‐borne dockerins, have been characterized recently. In this study, we cloned, expressed and characteri...

Summary A cellulolytic fiber‐degrading bacterium, R uminococcus champanellensis , was isolated from human faecal samples, and its genome was recently sequenced. Bioinformatic analysis of the R . champanellensis genome revealed numerous cohesin and dockerin modules, the basic elements of the cellulosome, and manual sequencing of partially sequenced genomic segments revealed two large tandem scaffoldin‐coding genes that form par...

Summary We present here a first attempt at modelling microbial dynamics in the human colon incorporating both uncertainty and adaptation. This is based on the development of a M onod‐equation based, differential equation model, which produces computer simulations of the population dynamics and major metabolites of microbial communities from the human colon. To reduce the complexity of the system, we divide the bacterial commun...

Summary The recently isolated bacterial strain 80/3 represents one of the most abundant 16S rRNA phylotypes detected in the healthy human large intestine and belongs to the R uminococcaceae family of F irmicutes. The completed genome sequence reported here is the first for a member of this important family of bacteria from the human colon. The genome comprises two large chromosomes of 2.24 and 0.73 M bp, leading us to propose...

Summary The pH of the colonic lumen varies with anatomical site and microbial fermentation of dietary residue. We have investigated the impact of mildly acidic pH, which occurs in the proximal colon, on the growth of different species of human colonic bacteria in pure culture and in the complete microbial community. Growth was determined for 33 representative human colonic bacteria at three initial pH values (approximately 5.5...

Summary Many of the substrates available as energy sources for microorganisms in the human colon, including dietary plant fibre and secreted mucin, are insoluble. It seems likely that such insoluble substrates support a specialized microbiota, and in order to test this hypothesis, faecal samples from four healthy subjects were fractionated into insoluble (washed particulate) and liquid fractions. Analysis of 1252 PCR‐amplified...

Summary The microbiota of the human intestinal tract play an important role in health, in particular by mediating many of the effects of diet upon gut health. Surveys of 16S rRNA sequence diversity in the human colon have emphasized the low proportion of sequences that match cultured bacterial species. This may reflect limited recent effort on cultivation rather than inherent unculturability, however, as anaerobic isolation me...

Summary Insoluble plant polysaccharides and endogenous mucin are important energy sources for human colonic microorganisms. The object of this study was to determine whether or not specific communities colonize these substrates. Using faecal samples from four individuals as inocula for an anaerobic in vitro continuous flow system, the colonization of wheat bran, high amylose starch and porcine gastric mucin was examined. Recov...