Soil geochemical parameters influencing the spatial distribution of anthrax in Northwest Minnesota,USA

Bacillus anthracis is the pathogenic bacterium that causes anthrax, which dwells in soils as highly resilient endospores. B. anthracis spore viability in soil is dependent upon environmental conditions, but the soil properties necessary for spore survival are unclear. In this study we used a range of soil geochemical and physical parameters to predict the spatial distribution of B. anthracis in northwest Minnesota, where 64 cases of anthrax in livestock were reported from 2000 to 2013. Two modeling approaches at different spatial scales were used to identify the soil conditions most correlated to known anthrax cases using both statewide and locally collected soil data. Ecological niche models were constructed using the Maximum Entropy (Maxent) approach and included 11 soil parameters as environmental inputs and recorded anthrax cases as known presences. One ecological niche model used soil data and anthrax presences for the entire state while a second model used locally sampled soil data (n = 125) and a subset of anthrax presences, providing a test of spatial scale. In addition, simple logistic regression models using the localized soil data served as an independent measure of variable importance. Maxent model results indicate that at a statewide level, soil calcium and magnesium concentrations, soil pH, and sand content are the most important properties for predicting soil suitability for B. anthracis while at the local level, clay and sand content along with phosphorous and strontium concentrations are most important. These results also show that the spatial scale of analysis is important when considering soil parameters most important for B. anthracis spores. For example, at a broad scale, B. anthracis spores may require Ca-rich soils and an alkaline pH, but may also concentrate in microenvironments with high Sr concentrations. The study is also one of the first ecological niche models that demonstrates the major importance of soil texture for defining the ecological niche of B. anthracis. These results will help improve our understanding of the soil geochemical conditions most suitable for B. anthracis as well as more reliably identify areas where anthrax may be found to focus prevention and remediation efforts.     

Rock varnish in New York: An accelerated snapshot of accretionary processes

Samples of manganiferous rock varnish collected from fluvial, bedrock outcrop and Erie Barge Canal settings in New York state host a variety of diatom, fungal and bacterial microbial forms that are enhanced in manganese and iron. Use of a Dual-Beam Focused Ion Beam Scanning Electron Microscope to manipulate the varnish in situ reveals microbial forms that would not have otherwise been identified. The relative abundance of Mn-Fe-enriched biotic forms in New York samples is far greater than varnishes collected from warm deserts. Moisture availability has long been noted as a possible control on varnish growth rates, a hypothesis consistent with the greater abundance of Mn-enhancing bioforms. Sub-micron images of incipient varnish formation reveal that varnishing in New York probably starts with the mortality of microorganisms that enhanced Mn on bare mineral surfaces; microbial death results in the adsorption of the Mn-rich sheath onto the rock in the form of filamentous networks. Clay minerals are then cemented by remobilization of the Mn-rich material. Thus, the previously unanswered question of what comes first - clay mineral deposition or enhancement of Mn - can be answered in New York because of the faster rate of varnish growth. In contrast, very slow rates of varnishing seen in warm deserts, of microns per thousand years, make it less likely that collected samples will reveal varnish accretionary processes than samples collected from fast-accreting moist settings.     

湛江港南三岛近岸海区异养细菌数量变动与潮汐周期关系研究

研究了南三岛近岸海区异养细菌数量变动与潮汐周期的关系。结果表明：在２４ｈ内异养细菌的数量随着潮位的上升而减少或随着潮位的下降而增加，高平潮时数量最低，低平潮时数量最高。比较一个月内各个高平潮异养细菌的数量，发现异养菌数量在小潮期向大潮期转变的过程中达到顶峰，并在大潮期急剧下降至最低值，接着从大潮期至小潮期，异养细菌数量缓慢回升，直至小潮期后才快速地上升。在水平分布中，异养细菌的数量在潮间带最大，其次是离低潮线１００ｍ的海区，离低潮线３００ｍ的海区最小。在垂直分布中．异养细菌数量以表层水最高，中层水次之，底层水最低。     

三种植物生长激素对光合细菌生长影响的研究

研究了不同浓度的三十烷醇、α-萘乙酸和赤霉素对光合细菌生长的影响。结果表明这三种植物生长激素对光合细菌的生长均有促进作用。其中赤霉素的促生作用最明显,其最佳质量浓度为0.5 mg/L。三十烷醇和α-萘乙酸的最佳质量浓度均是1.0 mg/L。试验表明在增殖培养中,通过添加某些植物生长激素,来促进光合细菌的生长是可行的。     

越冬亲虾及其环境的细菌学研究

通过对亲虾越冬系统的外蓄水池、预热池水、虾池水、亲虾用饵料、虾体及其病患作细菌分析,发现从外蓄水至虾体这五个环节存有细菌等微生物富集过程。稳定的环境、过多的营养、残饵、污物、病虾等是亲虾池细菌富集的要因;不健康亲虾富集并扩散病原微生物。对虾病病因、种类、亲虾成活率等的分析,发现至少31％的疾病与细菌等微生物有关。亲虾成活率与环境微生物一些参数,如几丁质降解菌含量、C/H％和V/H％间有很好的负相关。结果表明,监测亲虾越冬期各类细菌消涨势态,防治病害等是提高亲虾质量数量乃至育苗成功不可少的工作。     

The role of microorganisms on the mineralogical and geochemical characteristics of the Parnassos-Ghiona bauxite deposits,Greece

The Parnassos-Ghiona bauxite deposits of Greece are hosted within carbonate rocks and have been formed during different geological ages. The most economically important deposits occur in the B3 bauxite horizon, which is developed over long distance as a continuous layer of 1–10 m in thickness, within Cretaceous limestones. Due to intense tectonics, a significant (approximately 30 vol.%) bauxite ores along and near their contact with faults show a brittle deformation and change in the color from red to black-gray, in a distance of tens of meter. Commonly gray to whitish bauxites are aluminum-enriched (> 65 wt.% Al₂O₃) and iron depleted.     

Aerosol bacteria over the Southern Ocean during ACE-1

Individual bacterial cells occur in many samples that were collected at Cape Grim, Tasmania and during the Lagrangian “B” experiment of the Aerosol Characterization Experiment 1 (ACE-1) campaign that was conducted above the Southern Ocean. They are present in samples from altitudes as high as 5.4 km. Morphologically, almost all bacteria are rod-shaped, about 1 μm long or smaller, have one polar flagellum, and contain inclusions that are rich in P and K. Their morphological features suggest that these bacteria are motile, marine species. It seems likely that the cells became airborne by the same bubble-bursting mechanism that ejects sea-salt aerosol particles into the atmosphere; however, the bacteria and sea-salt particles are typically not aggregated with one another. The estimated number ratio of bacteria and the dominant aerosol species, sea salt, varies in the samples and averages about 1%. The aerosol bacteria seem to represent an important atmospheric reservoir of P and organic compounds; on the other hand, since they are externally mixed with sea salt, they are unlikely to be effective as cloud condensation nuclei.     

Characterization of natural colloids from a river and spring in a karstic basin

 Colloids are known to transport contaminants over long distances in natural media. Despite this potentially harmful effect, very few studies have been undertaken in subsurface aquifers. This paper presents the first results of a study of natural colloids and particles in a karstic aquifer. The site was chosen for its coverage by clay layers and peat which deliver various and numerous particle types in water. The methodological part describes three methods used for size determination and sample fractionation of surface water and spring water. These methods have been adapted for the treatment of multiple samples due to the rapid discharge variation typical of karstic aquifers. The analysis of many particle size distributions (PSD) shows that they can be described by a Pareto law. The variation of the slope of the PSD at the spring is mainly dependent on discharge. This behavior is interpreted as a washing of the karstic drains during the first phase of high flow events. Fractionation of the samples allowed application of various characterization techniques to particle size classes. X-ray diffraction (XRD) patterns showed that most of the mineral particles originated from Quaternary deposits and limestones. However the use of scanning electron micrsocopy with energy-dispersive spectrometer (SEM-EDS) detailed the composition of individual particles and revealed particles not found by XRD. These techniques also showed the high complexity of the natural particles and the important place of coprecipitation in their formation. Consequences on the fluxes of particulate matter and its potential role as a carrier of contaminants are discussed. Received: 28 October 1996 · Accepted: 7 July 1997     

Jet drop enrichment of bacteria,virus, and dissolved organic material

Four parameters that control the enrichment of bacteria in jet drops are bubble scavenging, drop size, drop position in the jet set, and the type of bacteria. Without the scavenging of bacteria as a bubble rises through the water it is doubtful that the observed enrichment factors, EF, greater than 1000 could be obtained. There is a maximum in EF as a function of top jet drop size, and the EF decreases from the top to the bottom drop of the jet set. The efficiency by which bubbles scavenge bacteria varies with species. Presumably these parameters apply in some degree to the EF of virus in jet drops. Dissolved organic material in natural waters can adsorb to bubbles and contribute to a large EF in jet drops, but there is a feedback mechanism whereby changes in bubble surface free energy modify the jet drop-size distribution. However, there is reason to believe this will not significantly influence the jet drop-size distribution produced by bubbles in the sea.     

Untersuchung von drei Grundwasserwerken auf Vorkommen von Acanthamoeben,Naeglerien und anderen freilebenden Amöben

Prevalence of Acanthamoebae, Naegleriae and Other Free-living Amoebae in the Course of Water Treatment in Three Well Waterworks Numerous species of free-living amoebae and other protozoa had been observed in the raw water of three representative waterworks with enriched well water. They were eliminated most effectively during the water treatment procedure. Acanthamoebae and Naegleriae including thermophilic strains of these genera could not be identified in any of the clear water samples. Acanthamoebae and Vannellae isolated from different samples exhibited repeatedly intracellular infections with bacteria of the genus Cytophaga. Their role as possible hosts of different pathogenic and non pathogenic bacteria like Legionella sp., Listeria sp., and Pseudomonas sp. is confirmed by this observation. As known from earlier findings in connection with the Acanthamoeba-Legionella model, it can be assumed, that bacteria multiplying in trophozoites or being enclosed in cysts are protected against high concentrations of chlorine and other biocides.