Studies on the effect of Polycyclic Aromatic Hydrocarbons in the life and activity of Perna spp

In the present study an endeavour has been made to analyse the acute toxicity of WAFs of Bombay High crude and Light Diesel oil on commercially important bivalve species Perna viridis and Perna indica by static bioassay methods. The toxic effects of chemicals in the WAF on the organisms ; their tissues and eventually on rate functions have been elucidated. Marine oil pollution not only affects productivity and quality of marine organisms but also eventually affects the health of human population due to a possible health risk by way of consumption of oil contaminated seafood

Charakterisierung der mikrobiellen Population und Untersuchungen zum Quorum Sensing in der Rhizosphäre vom Weidelgras (Lolium perenne) auf einer Rückstandshalde der Kaliindustrie

Im Rahmen dieser Dissertation wurden die Dynamik und die Kommunikation innerhalb der mikrobiellen Population der Rhizosphäre von Deutschem Weidelgras (Lolium perenne) untersucht, welches auf einer teilweise rekultivierten Rückstandshalde der Kaliindustrie wuchs. Um die niederschlagsbedingte Auswaschung von Salzen zu reduzieren, wird die Rückstandshalde des Kaliwerks Sigmundshall (in Bokeloh bei Hannover) schrittweise mit dem technogenen Abdecksubstrat REKAL/SAV ummantelt. Dieses weist eine hohe Standfestigkeit und Wasserspeicherkapazität auf und kann zudem begrünt werden, wofür als Pionierpflanze Lolium perenne dient. Durch diese Rekultivierung wird Niederschlag besser gespeichert und über Evapotranspiration wieder in die Luft abgegeben, was letztendlich die Bildung von Salzwasser vermindert. Da das Abdecksubstrat neben alkalischem pH-Wert auch teilweise hohe Schwermetallkonzentrationen aufweist, sollte in der vorliegenden Arbeit erstmals die mikrobielle Rhizosphären-Gemeinschaft in diesem extremen Habitat mittels einer kulturunabhängigen Methode erforscht werden. Zudem wurden erste Untersuchungen angestellt, ob im Substrat die zelldichte-abhängige bakterielle Kommunikation (Quorum Sensing) nachgewiesen werden kann. Mittels extrahierter Gesamt-DNA wurde anhand der 16S rDNA die Analyse des „Terminalen Restriktonsfragmentlängenpolymorphismus“ (TRFLP) verwendet, um die komplexe bakterielle Rhizosphären-Gemeinschaft unter zeitlichen und lokalen Aspekten zu vergleichen. Auftretende Veränderungen bei den bakteriellen Populationen der jeweiligen Proben wurden durch eine Zu- oder Abnahme der auch als Ribotypen bezeichneten terminalen Restriktionsfragmente (TRF) erfasst. Hierbei zeigten sich am Südhang der Halde während der Sommermonate der Jahre 2008 und 2009 zwar Schwankungen in den bakteriellen Gemeinschaftsprofilen, es lagen jedoch keine eindeutigen Dynamiken vor. Im Vergleich zum Südhang der Halde wies der Nordhang eine höhere Ribotyp-Diversität auf, was mit der fortgeschritteneren Rekultivierung dieses Haldenabschnitts zusammenhängen könnte. Zusätzlich wurden Bakterien aus der Rhizosphäre von Lolium perenne isoliert und mithilfe der Biosensoren Agrobacterium tumefaciens A136 pCF218 pCF372 und Chromobacterium violaceum CV026 auf die Produktion von N-Acylhomoserinlactonen (AHLs) überprüft. Diese AHLs werden von Gram-negativen Mikroorganismen als Signalmoleküle verwendet, um ihre Genexpression zelldichteabhängig zu kontrollieren. Von den 47 getesteten Gram-negativen Rhizosphärenisolaten konnten nur bei einem reproduzierbar AHL-Moleküle mithilfe des Reporterstamms A. tumefaciens nachgewiesen werden. Der AHL-Produzent wurde als Pseudomonas fluorescens identifiziert. Mittels dünnschichtchromatographischer Analysen konnten die extrahierten bakteriellen AHL-Moleküle den N-Octanoyl-L-homoserinlactonen zugeordnet werden.

Characterization of resistance in vitro to different antimicrobial in strains of Staphylococcus spp. in a hospital of the city of Valledupar between January and July 2009

The Staphylococcus spp. they can cause a wide range of infections systemic and located in community and hospital patients. Its high pathogenicity and growing resistance to multiple antimicrobials including methicillin, causes high morbiditymortality rates, causing a high epidemiological impact. Objective: to determine the phenotypic profile of resistance to different antimicrobials in strains of the genus Staphylococcus spp. Materials and methods: collected 75 strains and determined them susceptibility to different antibiotics by the Kirby-Bauer method. The production of betalactamasecheck using the nitrocefin test. (Resistance to Methicillin in S. aureus was conductedusing Mueller Hinton with 4% NaCl and oxacillin 6 μg/mL). Inducible clindamycin resistance tamizo by D-Test test. Results: they were isolated by 38% of staphylococcus coagulase negative (SNA) and 62% of S. aureus. 53% were penicillin resistant staphylococci: S. aureus with 58% and 42% SNA. 47% of the strains showed resistance to methicillin: S. aureus with 61% and SNA with 39%. A strain of S. aureus showed inducible resistance to clindamycin (1.33%). Coagulase negative staphylococci were isolated mostly from blood samples (31%), blood (29%), tip of catheter (5%) and came mostly from neonatal ICU (25%), medical (21%) and surgery (16%).Conclusions: S. aureus and SNA were isolated with greater frequency in blood and wounds from surgery and neonatal ICU. The predominant resistance phenotypes were penicillin and oxacillin.

Avaliação da ocorrência de Giardia spp. por diferentes métodos coprológicos

O género Giardia inclui espécies com potencial zoonótico e com uma distribuição mundial, e em que alguns genótipos de Giardia duodenalis são responsáveis anualmente por milhares de novos casos em humanos. Existem vários ciclos de transmissão, sendo a água de consumo, por contaminação fecal de origem animal, uma das principais fontes de infecção humana. Neste estudo foram colhidas 162 amostras fecais de animais de quatro origens diferentes (Zoológico = 55; Produção = 25; Doméstico = 5; Canil = 77) que foram testadas por duas técnicas coprológicas diferentes, a técnica de flutuação com sacarose e a técnica de sedimentação com formol-acetato. Para a implementação de Nested PCR foram testados vários genes, β-giardina, Glutamato desidrogenase e 18SrRNA, ocorrendo apenas amplificação das amostras com o gene 18SrRNA. Com esta técnica foram analisadas 26 amostras, que incluía a treze positivas à microscopia e as restantes escolhidas aleatoriamente. Este trabalho permitiu determinar a ocorrência de Giardia spp. através das técnicas coprológicas em treze animais de diferentes origens e verificar que o número de animais de canil positivos não foi o esperadas de acordo com o descrito na literatura que refere ser este o grupo com maior prevalência. Este estudo também permitiu uma comparação entre os dois métodos de concentração de quistos de Giardia spp., com maior recuperação utilizando a técnica de flutuação com sacarose. Através da técnica molecular confirmaram-se dez dos positivos encontrados por microscopia e ainda se detectaram dois novos positivos.

Determination of the impact of continuous defoliation of Lolium perenne and Trifolium repens on bacterial and fungal community structure in rhizosphere soil

To determine the effects of defoliation on microbial community structure, rhizosphere soil samples were taken pre-, and post-defoliation from the root tip and mature root regions of Trifolium repens L. and Lolium perenne L. Microbial DNA isolated from samples was used to generate polymerase chain reaction-denaturing gradient gel electrophoresis molecular profiles of bacterial and fungal communities. Bacterial plate counts were also obtained. Neither plant species nor defoliation affected the bacterial and fungal community structures in both the root tip and mature root regions, but there were significant differences in the bacterial and fungal community profiles between the two root regions for each plant. Prior to defoliation, there was no difference between plants for bacterial plate counts of soils from the root tip regions; however, counts were greater in the mature root region of L. perenne than T. repens. Bacterial plate counts for T. repens were higher in the root tip than the mature root region. After defoliation, there was no effect of plant type, position along the root or defoliation status on bacterial plate counts, although there were significant increases in bacterial plate counts with time. The results indicate that a general effect existed during maturation in the root regions of each plant, which had a greater impact on microbial community structure than either plant type or the effect of defoliation. In addition there were no generic consequences with regard to microbial populations in the rhizosphere as a response to plant defoliation.

Exudation of alcohol and aldehyde sugars from roots of defoliated Lolium perenne L. grown under sterile conditions

Root exudates were collected over a 27 day period from defoliated and non-defoliated Lolium perenne L. plants grown under sterile conditions in microlysimeters. Eleven individual sugars, including both aldehyde and alcohol sugars, were identified and quantified with a gas chromatograph-mass spectrometer (GC-MS). There was no change in the number of sugars present between 7 and 27 days, but the exudation of alcohol sugars decreased rapidly at about day 12. Xylose and glucose were present in the largest amounts. Defoliation initially increased the total amount of sugars in the exudates, but continuous defoliation reduced total sugar exudation by 16% and induced changes in the exudation patterns of individual sugars. Defoliation enhanced exudation of erythritol, threitol, and xylitol, reduced exudation of glucose and arabitol, but had little effect on the amounts of other sugars exuded. The more complex 6 C, 5 OH aldehyde sugars, especially glucose, showed changes earlier and to a greater extent (17 days), than the 5 C, 4 OH (xylose and ribose) and 6 C 4 OH (fucose) aldehyde groups. These findings confirm the general finding that repeated defoliation reduces the quantity of total sugars exuded, but the pattern of release of individual sugars is complex and variable.

Nitrosospira spp. can produce nitrous oxide via a nitrifier denitrification pathway

Nitrous oxide (N2O) emission from soils is a major contributor to the atmospheric loading of this potent greenhouse gas. It is thought that autotrophic ammonia oxidizing bacteria (AOB) are a significant source of soil-derived N2O and a denitrification pathway (i.e. reduction of NO2- to NO and N2O), so-called nitrifier denitrification, has been demonstrated as a N2O production mechanism in Nitrosomonas europaea. It is thought that Nitrosospira spp. are the dominant AOB in soil, but little information is available on their ability to produce N2O or on the existence of a nitrifier denitrification pathway in this lineage. This study aims to characterize N2O production and nitrifier denitrification in seven strains of AOB representative of clusters 0, 2 and 3 in the cultured Nitrosospira lineage. Nitrosomonas europaea ATCC 19718 and ATCC 25978 were analysed for comparison. The aerobically incubated test strains produced significant (P < 0.001) amounts of N2O and total N2O production rates ranged from 2.0 amol cell(-1) h(-1), in Nitrosospira tenuis strain NV12, to 58.0 amol cell(-1) h(-1), in N. europaea ATCC 19718. Nitrosomonas europaea ATCC 19718 was atypical in that it produced four times more N2O than the next highest producing strain. All AOB tested were able to carry out nitrifier denitrification under aerobic conditions, as determined by production of N-15-N2O from applied N-15-NO2-. Up to 13.5% of the N2O produced was derived from the exogenously applied N-15-NO2-. The results suggest that nitrifier denitrification could be a universal trait in the betaproteobacterial AOB and its potential ecological significance is discussed.

The impact of Eisenia veneta on As, Cu, Pb and Zn uptake by ryegrass (Lolium perenne L)

Earthworms are an essential part of the soil fauna in many global soils, represent a significant proportion of the soil biomass and are regarded as a useful indicator of soil health and quality (Edwards, 2004). They are also often the subject of inoculation programmes during the restoration of degraded lands (Butt, 1999) and the inoculation of earthworms to metal-contaminated soils has been suggested (Dickinson, 2000) largely due to the role earthworms are known to play in soil formation at such sites (Frouz et al., 2007).

Genotypic differences in the growth of bananas (Musa spp.) infected with migratory endoparasitic nematodes. 1. Roots

The effects of nematodes on root morphology and the association of root characteristics with resistance to nematodes of seven banana varieties were investigated in two experiments. Banana plants were grown in controlled conditions within polytunnels and harvested on three occasions for the measurement of root morpholopy, and biomass. Varieties differed in their resistance to nematodes, from resistant (Yg Km5, FHIA 17, FHIA 03) and partly resistant (FHIA 01, FHIA 25) to not resistant ((FHIA 23, Williams). Nematodes reduced the root dry weight of FHIA 01, FHIA 17 and FHIA 23 at some harvests. Primary root number was on average 9.5% lower in nematode-infected plants than controls, with no differences among the varieties. Thus, there was no simple association between the resistance of these varieties and their tolerance to nematodes. Varieties differed in root morphology. Root dry weight was greatest for resistant varieties Yg Km5 and FHIA 03, and least for non-resistant varieties FHIA 23 and Williams. Thus, resistance to nematodes was associated with varieties with greater root mass and more and larger primary roots.