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Introduced, invasive plants can alter local soil chemistry and microbial communities, but the underlying mechanisms and extent of these changes are largely unknown. Based on characteristics associated with invasiveness in plants, it was hypothesized that introduced species that produce large amounts of litter with distinctive secondary compounds can a) alter the chemistry of both extractable and bulk carbon in the soil, b) shift microbial communities towards microbes better able to metabolize the compounds in the litter and c) cause soil carbon chemistry and microbial communities to shift to relatively uniform, novel states at multiple sites. Composition of phenolics in senescent tissues (leaves and roots) of Polygonum cuspidatum was compared to the composition of extractable phenolics and non-extractable bulk organic carbon in soils under and adjacent to large, long-established stands of P.cuspidatum at four sites in the eastern U.S. Rates of degradation of phenolics, activities of enzymes associated with the breakdown of phenolics and shifts in microbial community composition were also measured at the sites. Soils under P.cuspidatum stands contained twice as much phenolics as adjacent soils, but the composition of phenolics differed greatly between soils under stands and senescent tissues of P.cuspidatum. Flavonoids and proanthocyanidins constituted >90% of the identified phenolics in P.cuspidatum tissues, whereas monophenolic compounds accounted for >90% of the phenolics in soils under stands. Soils under and adjacent to stands also exhibited distinctive compositions of relatively persistent bulk organic carbon; composition differed less between soils under stands at different sites than between soils under and adjacent to stands at the same site. Soils under P.cuspidatum had 28 times greater abundance of fungi than soils adjacent to stands, and fungal markers showed clear separation of soils under and adjacent to P.cuspidatum. However, the potential activity of enzymes that degrade polyphenols was lower in soils under stands. Exogenously applied, chemically complex polyphenols persisted in both P.cuspidatum-invaded and adjacent non-invaded soils, whereas less complex compounds rapidly disappeared from both soils.Synthesis. Results suggest that interactions between plant inputs, abiotic reactions and biotic transformations may create and maintain new states in invaded soils that are chemically and biologically less diverse. In the case of polyphenol-rich, fast-growing invasive species, these interactions may alter the composition of bulk soil organic matter that has relatively slower turnover rates, resulting in legacy effects. Restoration could thus require, not just removal of the species, but also post-removal interventions such as soil amendments.

This study was conducted to isolate and characterize soil microorganisms capable of solubilizing Chilembwe and Sinda rock phosphates readily available in Zambia. Single isolates were obtained by direct plating and enrichment cultures with succinate, cellulose and glucose as the carbon sources. Isolates were differentiated using colony morphology (form, margin, elevation and colour) and a subset of 20 was chosen for identification using the 16S rRNA gene sequences. After being cultured in nutrient broth and defined medium with tricalcium phosphate as the sole phosphate source, ten isolates were characterized for acid phosphatase enzyme activity. Over 80 isolates were obtained from different rock phosphate-sugar combinations. Isolates had varying morphological characteristics and the 20 strains identified showed a large diversity of organisms belonging to the genera Enterobacter, Burkholderia, Arthrobacter, Bacillus, Beijerinckia and two genera not previously reported to have P-solubilizing capabilities, Dyella and Curtobacterium. Both the observed growth and genera to which isolates belonged were dependent on the type of rock phosphate. Almost all isolates tested showed acid phosphatase activity that were similar to previously reported levels, ranging from 0.62 to 4.8 µg p-nitrophenol per 108 cells per hour. This work will be useful as the basis for the development of appropriate seed inocula that can enhance Sinda and Chilembwe rock phosphate dissolution and increased plant available P for crop production. Key words: Chilembwe, Sinda, Rock Phosphate, Burkholderia, Enterobacter, Rhizobia, Dyella, Arthrobacter, Curtobacterium, Dyella.

Galactooligosaccharides (GOS), prebiotic nondigestible oligosaccharides derived from lactose, have the potential for improving mineral balance and bone properties. This study examined the dose-response effect of GOS supplementation on calcium and magnesium absorption, mineral retention, bone properties, and gut microbiota in growing rats. Seventy-five 4-week-old male Sprague-Dawley rats were randomized into one of five treatment groups (n = 15/group) and fed a diet containing 0, 2, 4, 6, or 8% GOS by weight for 8 weeks. Dietary GOS significantly decreased cecal pH and increased cecal wall weight and content weight in a dose-dependent manner (p < 0.0001). Fingerprint patterns of the 16S rRNA gene PCR-DGGE from fecal DNA indicated the variance of bacterial community structure, which was primarily explained by GOS treatments (p = 0.0001). Quantitative PCR of the samples revealed an increase in the relative proportion of bifidobacteria with GOS (p = 0.0001). Net calcium absorption was increased in a dose-response manner (p < 0.01) with GOS supplementation. Dietary GOS also increased (p < 0.02) net magnesium absorption, femur ⁴⁵Ca uptake, calcium and magnesium retention, and femur and tibia breaking strength. Distal femur total and trabecular volumetric bone mineral density (vBMD) and area and proximal tibia vBMD increased (p < 0.02) with GOS supplementation. Trabecular-rich bones, that is, those that rapidly turn over, were most benefited. Regression modeling showed that GOS benefited calcium and magnesium utilization and vBMD through decreased cecal pH, increased cecal wall and content weight, and increased proportion of bifidobacteria.

The notion of community has been at the heart of the Internet since its inception. For many years, scientists have used the Internet to share data, collaborate on research, and exchange messages. In essence, scientists formed interactive research communities that existed not on a physical campus but on the Internet. Within the last few years, millions of computer users worldwide have begun to explore the Internet and commercial on-line services such as Prodigy and America Online. Many have joined one or more of the communities that have sprung up to serve consumer needs for Communication, information, and entertainment. One of the oldest virtual communities is the Well, launched in 1985 by a group of high-tech enthusiasts located primarily near San Francisco. Over the past decade, thousands of computer users have communicated with one another through the Well and, over time, developed strong personal relationships off-line.