Wechselwirkungen von Mikroorganismen und Tonmineralen-eine Übersicht

Relationships Between Soil Microorganisms and Clay Minerals-a Review Clay minerals belong to the most important environmental factors in soils, influencing the composition and metabolic activity of soil microflora. Their influence on bacteria, actinomycetes and microscopic fungi is very complex and includes trophogenic relationships, cation exchange capacity, sorptive activity, osmotic and other physico-chemical effects in microbial environments. In this review, different effects of clay minerals on soil microorganisms and also the influence of microorganisms on the clay minerals are briefly discussed.     

Ferulic acid release and 4-vinylguaiacol formation during brewing and fermentation: indications for feruloyl esterase activity in Saccharomyces cerevisiae

The release of ferulic acid and the subsequent thermal or enzymatic decarboxylation to 4-vinylguaiacol are inherent to the beer production process. Phenolic, medicinal, or clove-like flavors originating from 4-vinylguaiacol frequently occur in beer made with wheat or wheat malt. To evaluate the release of ferulic acid and the transformation to 4-vinylguaiacol, beer was brewed with different proportions of barley malt, wheat, and wheat malt. Ferulic acid as well as 4-vinylguaiacol levels were determined by HPLC at several stages of the beer production process. During brewing, ferulic acid was released at the initial mashing phase, whereas moderate levels of 4-vinylguaiacol were formed by wort boiling. Higher levels of the phenolic flavor compound were produced during fermentations with brewery yeast strains of the Pof(+) phenotype. In beer made with barley malt, ferulic acid was mainly released during the brewing process. Conversely, 60-90% of ferulic acid in wheat or wheat malt beer was hydrolyzed during fermentation, causing higher 4-vinylguaiacol levels in these beers. As cereal enzymes are most likely inactivated during wort boiling, the additional release of ferulic acid during fermentation suggests the activity of feruloyl esterases produced by brewer's yeast.     

Effects of soil invertebrates on the survival of some genetically engineered bacteria in leaf litter and soil

Seven bacterial strains, most of them bearing natural or recombinant plasmids, were introduced in oak leaf litter or soddy-podzolic soil. In these substrata, which contained litter-dwelling diplopods and isopods, or endogenic earthworms, bacteria survival was followed. In the absence of the animals, the numbers of introduced strains gradually decreased. In the presence of the animals, plasmid-bearing strains of Pseudomonas putida survived at 10⁵–10⁷ CFUs g^-1 up to 1.5 months in both leaves and soil. The total numbers of bacteria found in excrements from the soil macrofauna were 5–15 times higher than in the food. The numbers of P. putida in the excrements were equal to or higher than in the food. The numbers of Pseudomonas stutzeri JM302 (pLV1013) and Azospirillum brasiliense ATCC29710 (pFACII) in the excrements were always 2–10 times lower than in the food. The digestive fluid taken from the middle part of the gut of the diplopod Pachyiulus flavipes showed a strong antibacterial activity. Those bacteria with lower survival in the gut appeared to be more sensitive to digestion by the midgut fluid. In contrast, the hindgut fluid did not suppress the viability of P. stutzeri JM302 (pLV1013). We postulate that the introduced bacteria partially survive the midgut passage and then multiply with a high growth rate in the hindgut of the animals. The environmental consequences of the interactions between soil invertebrates and the released bacteria are discussed.Dedicated to Professor J. C. G. Ottow on the occasion of his 60th birthday     

Magic applied to roof experiments (Risdalsheia,N; Gårdsjön,S; Klosterhede,DK) to evaluate the rate of reversibility of acidification following experimentally reduced acid deposition

Soil and stream water responses to clean rain treatments at three roof covered forest ecosystems in Norway, Sweden and Denmark were modelled by the MAGIC model. The model outputs were compared with measured responses. Over the wide span in site conditions among the three sites MAGIC successfully reproduced the observed effects in the clean rain treatments. Seasalt influence caused single year discrepancies but the long term trends were well reproduced. In particular the significant decreases in SO₄ output were well reproduced. A simultaneous change in base cation leaching was observed, which in the long run will be the basis for the recovery of these acidified systems. The rate of recovery at the 3 studied sites was very slow.     

Sequential Extraction of Lead from Grain Size Fractionated River Sediments Using the Optimized BCR Procedure

Fluvial bed sediments are widely used for characterizing anthropogenic contaminant signals in urban watersheds. This study presents the first preliminary examination of sequentially extracted Pb from grain size fractionated bed sediments using the optimized (standardized) BCR procedure. Baseline sediment samples and samples from the vicinity of three storm-sewer outlets in Nuuanu Stream, Honolulu, Hawaii, were examined. The weighted average Pb liberated from four sequentially extracted phases was 144?±?26 mg/kg (±SD). These Pb concentrations are high compared to 3 mg/kg leached by a 0.5 M HCl solution, and 13 mg/kg from a 4-acid total digestion of baseline sediments. Over a 1.8 km section of stream channel, land use variations and traffic density differences had little impact on the magnitude of Pb in specific phases for each of the six grain size fractions examined. Regardless of grain size or spatial location, Pb in the reducible phase exceeded that in oxidizable, residual and acid extractable phases. Weighted reducible Pb concentrations for three sewer outlet sites ranged from 69 to 92 mg/kg, and this phase typically accounted for 70–80% of all labile Pb. The <63 μm grain size class did not exhibit the highest Pb concentration, instead this was found in either the 125–250 μm or 500–1,000 μm fractions. Examining bed sediment phase associations of Pb over a smaller length dimension (i.e., 40 m) centered around one sewer outlet, indicated higher concentrations at the outlet (180 mg/kg) compared to upstream (132 mg/kg) or downstream (150 mg/kg). The differences were primarily associated with higher Pb concentrations in the reducible and oxidizable phases of the coarse sand fractions (500–2,000 μm) at the outlet. Overall, all data point to a significant anthropogenic signal for Pb in bed sediments in the urbanized section of Nuuanu Stream.     

Exposure to non‐ionizing electromagnetic radiation of public risk prevention instruments threatens the quality of spermatozoids

The use of artificial insemination in cattle breeding has evolved to global extent, and insemination doses are often shipped via air transport which requires strict radiation‐based examinations. For the determination of effect of non‐ionizing radiation (NIR), to which are beings frequently exposed due to protection of airport or cultural event security, freshly ejaculated and cryopreserved bovine spermatozoa were used as experimental model. Following radiation with hand‐held metal detector in various exposition times (0, 10 s, 15, 30 and 60 min—groups FR, FR10, FR15, FR30 and FR60) the spermatozoa underwent motility and DNA fragmentation analyses. Study on cryoconserved semen treated with NIR was performed in time intervals 0, 10 s, 1 and 5 min (insemination doses radiated before cryoconservation—CB, CB10, CB1, CB5; samples radiated after freezing—CA, CA10, CA1 and CA5). Fresh semen and insemination doses radiated after cryoconservation showed significantly lower total and progressive motility. No effect on motility parameters was detected in semen extended with cryopreservative medium and radiated prior to freezing. Surprisingly, NIR showed a potential to stimulate spermatozoa velocity; however, the effect was modulated throughout the post‐thawing incubation. Based on the DNA fragmentation assay, sperm DNA stayed intact. Present study underlines the potential harm of NIR, which is frequently used in everyday life, with overall adverse impact on human and animal reproduction. Current study also points out on interesting short‐term spermatozoa stimulation induced by NIR.     

Phenolic compounds in seven South American Ilex species.

Ilex paraguariensis (common name: 'mate' or 'yerba mate') is used for the preparation of the most popular tea-like beverage of South America. Choleretic, hypocholesteremic, antioxidant, hepatoprotective and bitter taste properties of mate are attributed to the phenolic constituents of the leaves. I. paraguariensis has seven local congeneric substitutes or adulterants: I. brevicuspis; I. theezans; I. microdonta; I. dumosa var. dumosa; I. taubertiana; I. pseudobuxus; I. integerrima; and I. argentina. An HPLC method using UV with Photodiode Array Detector was developed for the identification and quantification of caffeoyl derivatives (caffeic acid, chlorogenic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid) and flavonoids (quercetin, rutin and kaempferol) in these species. I. paraguariensis showed a higher content of flavonoids and caffeoyl derivatives than the other assayed species.     

Campylobacter control in poultry by current intervention measures ineffective: urgent need for intensified fundamental research

Campylobacter-contaminated poultry meat is an important source of foodborne gastroenteritis and poses a serious health burden in industrialized countries. Broiler chickens are commonly regarded as a natural host for this pathogen and infected birds carry a very high Campylobacter load in their gastrointestinal tract, especially the ceca. This results in contaminated carcasses during processing. While hygienic measures at the farm and control measures during carcass processing can have some effect on the reduction of Campylobacter numbers on the retail product, intervention at the farm level by reducing colonization of the ceca should be taken into account in the overall control policy. This review gives an up-to-date overview of suggested on-farm control measures to reduce the prevalence and colonization of Campylobacter in poultry.     

Fungal colonization of coastal Douglas‐fir following mechanical commercial thinning damage

Commercial‐aged Douglas‐fir trees mechanically damaged during commercial thinning activities were investigated to quantify fungal taxa present 14 years after thinning. A total of 235 wood cores from 18 damaged and 18 non‐damaged control trees were obtained. Fungi were isolated on malt extract agar and molecular methods were used to identify 48 taxa. Damaged Douglas‐fir trees were more than twice as likely to contain wood‐inhabiting fungi as undamaged trees (p = 0.07) and contained more than 2.5 times more fungi (p = 0.006). However, typical Douglas‐fir stem‐decay fungi were not isolated. Fungi present were mostly endophytes and no significant differences were found in frequencies of decay/non‐decay soft‐rot fungi between damaged and control trees (p = 0.67). Likewise, no significant differences were found for the trend in number of fungi isolates over radial depth into the stem between damaged and control trees (p = 0.29). Frequency of fungal isolates was non‐linearly related to depth in the tree bole. Significant differences between damaged and control trees (p = 0.03) was influenced by the data in the outermost 3 mm. With the exception of these data, there were no significant differences between damaged and control trees in the radial trend in fungal frequency (p = 0.37). Results of this study suggest that wounding in commercial‐aged Douglas‐fir may not contribute significantly to occurrence and species composition of wood inhabiting fungi over the period of a short‐rotation final harvest. However, damage mitigation is recommended supported by a related study showing vertical discolouration affecting all wounded stems.     

Restriction Fragment Length Analysis of the Cytochrome b Gene and Muscle Fatty Acid Composition Differentiate the Cryptic Flatfish Species Solea solea and Solea aegyptiaca

Overlapping external morphometric characters easily confound the flatfishes Solea aegyptiaca and Solea solea (Soleidae) in areas of the Mediterranean Sea where both species live in sympatry. This leads to uncertainties in the fisheries and marketing of the species, in addition to misinterpretations in biogeography and conservation studies. This paper describes a simple restriction fragment length-based diagnostic test that differentiates S. solea from S. aegyptiaca, as well as from other species of the Soleidae family. Furthermore, the two species living in sympatry in the Gulf of Kavala (North Aegean Sea, Greece) present significant qualitative differences in muscle fatty acid composition, a property that can also be used to distinguish the two cryptic species.