Physical and Chemical Correlates of Microbial Activity and Biomass in Composting Municipal Sewage Sludge

Various physical and chemical parameters were monitored to evaluate their influence on the microbial communities present in composting municipal sewage sludge. Temperature, moisture content, depth, pH, protein content, total nitrogen, total carbon, lipid phosphate biomass, and the rates of microbial incorporation of substrates into lipids were measured at several times throughout the 17- to 19-day composting runs. Temperature was found to have the most consistent and dramatic effect on microbial activity and biomass. When temperatures exceeded 55 to 60°C, microbial activity fell dramatically, usually by more than 1 order of magnitude. Microbial activity was generally greatest in samples taken from the 35 to 50°C areas of the composting piles. Changes in the composition of the compost over time included increased pH, increased protein content, and decreased total organic content. The changes in these parameters appeared to reflect the microbial activity and biomass present. The results of this study indicate that the rate of composting may best be optimized by controlling the composting temperatures, provided that the other parameters fall within reasonable limits in the starting material.     

Improvements in and Environmental Applications of Double-Vial Radiorespirometry for the Study of Microbial Mineralization

Several variations in the scintillation mixture and the filter paper arrangements for double-vial radiorespirometry were compared. Improved efficiencies (44%) and shorter response times were found by adding wetting agents and methanolic NaOH to the scintillation mixture in the filter paper. The scintillation chemicals used did not contain dioxane and were found to be nontoxic to the test microbiota in this system. Covering the inner reaction vial with aluminum foil minimized the reduction in counting efficiency when testing colored or dense environmental samples. Mineralization rates were determined with ¹⁴C-labeled glucose, acetate, and glutamate and [¹⁴C]cellulose- and [¹⁴C]lignin-labeled lignocellulose for composting cow manure, forest soil, and arctic lake sediment microbiota. This improved method can be used in a variety of procedures involving the measurement of microbial mineralizations of organic compounds. Since no liquid scintillation cocktail is used for counting, the radioactive wastes are aqueous or can be incinerated, making disposal easy.     

Effect of chromium nicotinic acid supplementation on selected cardiovascular disease risk factors

The effects of daily supplemental chromium (200 μg) complexed with 1.8 mg nicotinic acid on plasma glucose and lipids, including total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides, were assessed in 14 healthy adults and 5 adults with noninsulin-dependent diabetes mellitus (NIDDM) using a double-blind crossover study with 8-wk experimental periods. Eight of the 14 healthy subjects and all 5 subjects with NIDDM also underwent an oral glucose tolerance test with assessment of 90 min postprandial plasma glucose and insulin concentrations. No statistically significant effects of chromium nicotinic acid supplementation were found on plasma insulin, glucose, or lipid concentrations, although chromium nicotinic acid supplementation slightly lowered fasting plasma total and LDL cholesterol, triglycerides, and glucose concentrations, and 90-min postprandial glucose concentrations in individuals with NIDDM.     

Effects of Acid on Plant Litter Decomposition in an Arctic Lake

The effects of acid on the microbial decomposition of the dominant aquatic macrophyte (Carex sp.) in Toolik Lake, Alaska were studied in microcosms during the ice-free season of 1980. Toolik Lake is slightly buffered, deep, and very oligotrophic. Microbial activities, as determined by ¹⁴C-acetate incorporation into extractable lipids, associated with Carex litter were significantly (P < 0.01) reduced within 2 days at pHs of 3.0 and 4.0, but not 5.0, 5.5, or 6.0, as compared with ambient controls (pH 7.4). ATP levels were significantly reduced at pH 3.0, but not at the other pHs tested. After 18 days, microbial activity significantly correlated with weight loss (P < 0.05), nitrogen content (P < 0.01), and C/N ratios (P < 0.01) of the litter, but did not correlate with ATP levels. Scanning electron microscopy of the litter surface revealed that the fungi present at ambient pH did not become dominant at pHs below 5.5, diatoms were absent below pH 4.0, and bacterial numbers and extracellular slime were greatly reduced at pH 4.0 and below. Mineralization of Carex¹⁴C-lignin-labeled or ¹⁴C-cellulose-labeled lignocellulose was reduced at pH 2.0, but not at pH 4.0, 5.0, or 6.0, compared with controls (pH 7). We concluded that if the pH of the water from this slightly buffered lake was sufficiently reduced, rates of litter decomposition would be significantly reduced.     

Endothelium Dependent Vasomotion and In Vitro Markers of Endothelial Repair in Patients with Severe Sepsis: An Observational Study

Background

Outcome in sepsis is mainly defined by the degree of organ failure, for which endothelial dysfunction at the macro- and microvascular level is an important determinant. In this study we evaluated endothelial function in patients with severe sepsis using cellular endothelial markers and in vivo assessment of reactive hyperaemia.

Materials and Methods

Patients with severe sepsis (n = 30) and 15 age- and gender- matched healthy volunteers were included in this study. Using flow cytometry, CD34+/KDR+ endothelial progenitor cells (EPC), CD31+ T-cells, and CD31+/CD42b- endothelial microparticles (EMP) were enumerated. Migratory capacity of cultured circulating angiogenic cells (CAC) was assessed in vitro. Endothelial function was determined using peripheral arterial tonometry at the fingertip.

Results

In patients with severe sepsis, a lower number of EPC, CD31+ T-cells and a decreased migratory capacity of CAC coincided with a blunted reactive hyperaemia response compared to healthy subjects. The number of EMP, on the other hand, did not differ. The presence of organ failure at admission (SOFA score) was inversely related with the number of CD31+ T-cells. Furthermore, the number of EPC at admission was decreased in patients with progressive organ failure within the first week.

Conclusion

In patients with severe sepsis, in vivo measured endothelial dysfunction coincides with lower numbers and reduced function of circulating cells implicated in endothelial repair. Our results suggest that cellular markers of endothelial repair might be valuable in the assessment and evolution of organ dysfunction.     

Root–root interactions: extending our perspective to be more inclusive of the range of theories in ecology and agriculture using in-vivo analyses

Background

There is a large body of literature on competitive interactions among plants, but many studies have only focused on above-ground interactions and little is known about root–root dynamics between interacting plants. The perspective on possible mechanisms that explain the outcome of root–root interactions has recently been extended to include non-resource-driven mechanisms (as well as resource-driven mechanisms) of root competition and positive interactions such as facilitation. These approaches have often suffered from being static, partly due to the lack of appropriate methodologies for in-situ non-destructive root characterization.

Scope

Recent studies show that interactive effects of plant neighbourhood interactions follow non-linear and non-additive paths that are hard to explain. Common outcomes such as accumulation of roots mainly in the topsoil cannot be explained solely by competition theory but require a more inclusive theoretical, as well as an improved methodological framework. This will include the question of whether we can apply the same conceptual framework to crop versus natural species.

Conclusions

The development of non-invasive methods to dynamically study root–root interactions in vivo will provide the necessary tools to study a more inclusive conceptual framework for root–root interactions. By following the dynamics of root–root interactions through time in a whole range of scenarios and systems, using a wide variety of non-invasive methods, (such as fluorescent protein which now allows us to separately identify the roots of several individuals within soil), we will be much better equipped to answer some of the key questions in root physiology, ecology and agronomy.     

Pollen morphology and its taxonomic significance in the tribe Gochnatieae (Compositae, Gochnatioideae)

In the context of recent molecular phylogenies of the basal grades of Compositae, we investigated the utility of pollen morphology within the tribe Gochnatieae. The pollen of 64 species of Anastraphia, Cnicothamnus, Cyclolepis, Gochnatia, Pentaphorus, and Richterago was studied using light microscopy and scanning electron microscopy. In addition, three extra-Gochnatieae genera (Ianthopappus, Leucomeris, and Nouelia) were examined as they were traditionally morphologically related to members of the tribe Gochnatieae. Three of the species of Gochnatieae were examined using transmission electron microscopy. Two pollen types, and two new subtypes, have been recognized on the basis of the pollen shape, size, and exine sculpture. The pollen features of Gochnatia sect. Moquiniastrum and G. cordata are similar and distinctive within the genus and support the recently re-circumscribed section Hedraiophyllum. Within the species with echinate pollen surface, the distinctive spine length of Anastraphia supports its recent resurrection as a genus. The identity of Pentaphorus could not be supported by pollen features as was for other morphological characteristics. The pollen features shared across Cyclolepis, Ianthopappus, Leucomeris, Nouelia and Gochnatia sect. Moquiniastrum, as well as those shared by Richterago and Anastraphia could be a result of parallel evolution.