A total of 159 endophytic bacteria were isolated from surface-sterilized root nodules of wild perennial Glycyrrhiza legumes growing on 40 sites in central and northwestern China. Amplified fragment length polymorphism (AFLP) genomic fingerprinting and sequencing of partial 16S rRNA genes revealed that the collection mainly consisted of Mesorhizobium, Rhizobium, Sinorhizobium, Agrobacterium and Paenibacillus species. Based on symbiotic properties with the legume hosts Glycyrrhiza uralensis and Glycyrrhiza glabra, we divided the nodulating species into true and sporadic symbionts. Five distinct Mesorhizobium groups represented true symbionts of the host plants, the majority of strains inducing N2-fixing nodules. Sporadic symbionts consisted of either species with infrequent occurrence (Rhizobium galegae, Rhizobium leguminosarum) or species with weak (Sinorhizobium meliloti, Rhizobium gallicum) or no N2 fixation ability (Rhizobium giardinii, Rhizobium cellulosilyticum, Phyllobacterium sp.). Multivariate analyses revealed that the host plant species and geographic location explained only a small part (14.4%) of the total variation in bacterial AFLP patterns, with the host plant explaining slightly more (9.9%) than geography (6.9%). However, strains isolated from G. glabra were clearly separated from those from G. uralensis, and strains obtained from central China were well separated from those originating from Xinjiang in the northwest, indicating both host preference and regional endemism.

We report here on novel groups of Archaea in the bacterioplankton of a small boreal forest lake studied by the culture-independent analysis of the 16S rRNA genes amplified directly from lake water in combination with fluorescent in situ hybridization (FISH). Polymerase chain reaction products were cloned and 28 of the 160 Archaea clones with around 900-bp-long 16S rRNA gene inserts, were sequenced. Phylogenetic analysis, including 642 Archaea sequences, confirmed that none of the freshwater clones were closely affiliated with known cultured Archaea. Twelve Archaea sequences from lake Valkea Kotinen (VAL) belonged to Group I of uncultivated Crenarchaeota and affiliated with environmental sequences from freshwater sediments, rice roots and soil as well as with sequences from an anaerobic digestor. Eight of the Crenarchaeota VAL clones formed a tight cluster. Sixteen sequences belonged to Euryarchaeota. Four of these formed a cluster together with environmental sequences from freshwater sediments and peat bogs within the order Methanomicrobiales. Five were affiliated with sequences from marine sediments situated close to marine Group II and three formed a novel cluster VAL III distantly related to the order Thermoplasmales. The remaining four clones formed a distinct clade within a phylogenetic radiation characterized by members of the orders Methanosarcinales and Methanomicrobiales on the same branch as rice cluster I, detected recently on rice roots and in anoxic bulk soil of flooded rice microcosms. FISH with specifically designed rRNA-targeted oligonucleotide probes revealed the presence of Methanomicrobiales in the studied lake. These observations indicate a new ecological niche for many novel 'non-extreme' environmental Archaea in the pelagic water of a boreal forest lake.

SummaryGastrointestinal symptoms and fecal frequency following ingestion of yogurt containing 15g of galacto-oligosaccharides (GOS) per d were observed in 12 healthy volunteers. The effect of GOS on intestinal microflora was also studied in six volunteers. Defecation frequency increased during the administration period, but gastrointestinal symptoms, especially flatulence, also increased. The level of fecal bifidobacteria did not increase by the yogurt intake, but a significant increase was observed in the fecal bacteria growing on MRS media. The results indicate that dietary GOS increase gastrointestinal symptoms and fecal frequency in normal adults and have an effect on intestinal microecosystem. Key Words galacto-oligosaccharides, gastrointestinal symptoms, bifido bacteria, defecation frequency Dietary fiber, as it passes to the colon, improves the colonic function (1). Fructo-oligosaccharides (FOS) are recently characterized components of the diet that are now considered in many countries as prebiotics and as a dietary fiber (2). A prebiotic is a "non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon that have the potential to improve host health" (3). The prebiotics that have been identified today and which have served to introduce this concept are carbohydrates that resist autoenzymic digestion and that are quantita tively fermented in the colon. FOS have been studied intensively over the past decade, and many positive health effects of FOS have been found (4). There is evidence that FOS relieve constipation, reduce the production of toxic substances

No abstract