qnrA gene diversity in Shewanella spp.

Members of Shewanella are ubiquitous in aquatic environments, some of which have been implicated in human infections. The progenitors of antibiotic resistance genes with clinical relevance, such as qnrA genes, have been identified in Shewanella. qnrA code for a pentapeptide repeat protein that protects type II topoisomerases, decreasing susceptibility to quinolones and fluoroquinolones. In this study, 248 genomes of 49 Shewanella species were analysed as well as 33 environmental isolates belonging to 10 Shewanella species. The presence of the qnrA gene was detected in 22.9% of the genomes and 15.2% of the isolates. The gene was more often detected in Shewanella algae, but was also detected in Shewanella carassii, Shewanella chilikensis, Shewanella haliotis and Shewanella indica. The identified genes encoded the previously described variants QnrA3 (in 22 genomes of one species), QnrA2 (eight genomes and three species), QnrA1 (six genomes and two species), QnrA7 (five genomes and two species), QnrA10 (two genomes of one species) and QnrA4 (one genome). In addition, 11 novel variants with 3 to 7 amino acid substitutions were identified (in 13 genomes and one environmental isolate). The presence of this gene appears to be species-specific although within some species several variants were detected. The study presents a previously unknown diversity of qnrA in Shewanella, highlighting the role of this genus as progenitor and reservoir of these genes. Further studies are needed to determine the phenotypes conferred by the new variants and the mechanisms that may mediate the transfer of these genes to new hosts.

Impact of Ag2S NPs on soil bacterial community - A terrestrial mesocosm approach.

Soils might be a final sink for Ag2S nanoparticles (NPs). Still, there are limited data on their effects on soil bacterial communities (SBC). To bridge this gap, we investigated the effects of Ag2S NPs (10 mg kg-1 soil) on the structure and function of SBC in a terrestrial indoor mesocosm, using a multi-species design. During 28 days of exposure, the SBC function-related parameters were analysed in terms of enzymatic activity, community level physiological profile, culture of functional bacterial groups [phosphorous-solubilizing bacteria (P-SB) and heterotrophic bacteria (HB)], and SBC structure was analysed by 16S rRNA gene-targeted denaturing gradient gel electrophoresis. The SBC exposed to Ag2S NPs showed a significative decrease of functional parameters, such as ß-glucosidase activity and L-arginine consumption, and increase of the acid phosphatase activity. At the structural level, significantly lower richness and diversity were detected, but at later exposure times compared to the AgNO3 treatment, likely because of a low dissolution rate of Ag2S NPs. In fact, stronger effects were observed in soils spiked with AgNO3, in both functional and structural parameters. Changes in SBC structure seem to negatively correlate with parameters related to phosphorous (acid phosphatase activity) and carbon cycling (abundance of HB, P-SB, and ß-glucosidase activity). Our results indicate a significant effect of Ag2S NPs on SBC, specifically on parameters related to carbon and phosphorous cycling, at doses as low as 10 mg kg-1 soil. These effects were only observed after 28 days, highlighting the importance of long-term exposure experiments for slowly dissolving NPs.

Regular and moderate aerobic training before allergic asthma induction reduces lung inflammation and remodeling.

Experimental studies have reported that aerobic exercise after asthma induction reduces lung inflammation and remodeling. Nevertheless, no experimental study has analyzed whether regular/moderate aerobic training before the induction of allergic asthma may prevent these inflammatory and remodeling processes. For this purpose, BALB/c mice (n = 96) were assigned into non-trained and trained groups. Trained animals ran on a motorized treadmill at moderate intensity, 30 min/day, 3 times/week, for 8 weeks, and were further randomized into subgroups to undergo ovalbumin sensitization and challenge or receive saline using the same protocol. Aerobic training continued until the last challenge. Twenty-four hours after challenge, compared to non-trained animals, trained mice exhibited: (a) increased systolic output and left ventricular mass on echocardiography; (b) improved lung mechanics; (c) decreased smooth muscle actin expression and collagen fiber content in airways and lung parenchyma; (d) decreased transforming growth factor (TGF)-ß levels in bronchoalveolar lavage fluid (BALF) and blood; (e) increased interferon (IFN)-γ in BALF and interleukin (IL)-10 in blood; and (f) decreased IL-4 and IL-13 in BALF. In conclusion, regular/moderate aerobic training prior to allergic asthma induction reduced inflammation and remodeling, perhaps through increased IL-10 and IFN-γ in tandem with decreased Th2 cytokines.

New molecular variants of epsilon and beta IncP-1 plasmids are present in estuarine waters.

In this work the presence of broad-host-plasmids in an estuary in Portugal has been investigated. Pseudomonas putida KT2442 was used as model recipient bacteria in biparental matings with tetracycline and mercury to select for resistance phenotypes. As a result, 7 transconjugants were shown to carry broad-host-plasmids from the IncP-1 group, as seen by PCR amplification of the trfA gene. Sequence analysis confirmed the isolation of 4 plasmids from ß-1 subgroup and 3 assigned to the recently described ε subgroup. To our knowledge this is the first report concerning the detection and isolation of IncP-1ß and ε plasmids in estuarine waters. Moreover it is shown that, even though the retrieved plasmids are phylogenetically close to previously characterized plasmids, such as pB10 and pKJK5, respectively, they constitute new molecular variants.

Prevalence of maxillary sinus septa: systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to determine the prevalence and characteristics of maxillary sinus septa using cone beam computed tomography and computed tomography data. Publications were searched until October 5, 2020 in three electronic databases. Additionally, article bibliographies were searched, and authors were contacted if required. This review has been registered in PROSPERO (CRD42019124933). Two independent evaluators assessed methodological quality using the Joanna Briggs Institute levels of evidence; inter-rater reliability tests were performed (Cohen's κ). The prevalence of maxillary sinus septa was expressed as a proportion; differences according to sex were reported in terms of the odds ratio (OR) and 95% confidence interval (95% CI). Heterogeneity and sources of heterogeneity were evaluated by meta-regression. Publication bias was assessed by visual analysis of the funnel plot. Statistical significance was set at P < 0.05. The 62 studies identified and included in the review involved 13,701 patients (22,460 sinuses). The meta-analysis of 35 studies (14,664 sinuses) revealed an overall mean sinus septa prevalence per sinus of 33.2% (95% CI 27.8-38.5%; I2 = 98.32%). The meta-analysis of 42 studies (9631 patients) found an overall mean sinus septa prevalence per patient of 41.0% (95% CI 36.0-46.0%, I2 = 96.45%). The OR for the difference in septa prevalence between sexes was 0.785 (95% CI 0.590-1.046; P = 0.098, I2 = 73.24%). Septa were most frequent in the middle area of the sinus and with a transverse orientation (86.0%). Within the limitations, the results suggest a high proportion of septa in the sinus, commonly in the middle area, which can interfere with the success of sinus floor elevation required for implant rehabilitation.

Diversity in UV sensitivity and recovery potential among bacterioneuston and bacterioplankton isolates.

AIMS: To assess the variability in UV-B (280-320 nm) sensitivity of selected bacterial isolates from the surface microlayer and underlying water of the Ria de Aveiro (Portugal) estuary and their ability to recover from previous UV-induced stress. METHODS AND RESULTS: Bacterial suspensions were exposed to UV-B radiation (3·3 W m⁻²). Effects on culturability and activity were assessed from colony counts and (3) H-leucine incorporation rates, respectively. Among the tested isolates, wide variability in UV-B-induced inhibition of culturability (37·4-99·3%) and activity (36·0-98·0%) was observed. Incubation of UV-B-irradiated suspensions under reactivating regimes (UV-A, 3·65 W m⁻²; photosynthetic active radiation, 40 W m⁻²; dark) also revealed diversity in the extent of recovery from UV-B stress. Trends of enhanced resistance of culturability (up to 15·0%) and enhanced recovery in activity (up to 52·0%) were observed in bacterioneuston isolates. CONCLUSIONS: Bacterioneuston isolates were less sensitive and recovered more rapidly from UV-B stress than bacterioplankton isolates, showing enhanced reduction in their metabolism during the irradiation period and decreased culturability during the recovery process compared to bacterioplankton. SIGNIFICANCE AND IMPACT OF THE STUDY: UV exposure can affect the diversity and activity of microbial communities by selecting UV-resistant strains and alter their metabolic activity towards protective strategies.

PCR-DGGE-based methodologies to assess diversity and dynamics of Aeromonas communities.

AIMS: Aeromonas is ubiquitous in aquatic environments and may cause infectious diseases in fish and humans. However, reliable and specific methods to evaluate the diversity and dynamics of Aeromonas populations are currently unavailable. This study aimed to develop PCR-DGGE methodologies for culture-independent analysis of Aeromonas populations in water systems. METHODS AND RESULTS: Three primer sets were designed to amplify selected sections of genes gyrB, rpoD and sodB from Aeromonas. Their specificity was confirmed by in silico analysis and by PCR on DNA from pure cultures. Estuarine water samples were analyzed by PCR-DGGE using those primers. DGGE patterns clearly clustered according to seasonal factors, and Aeromonas communities were surprisingly stable along a salinity gradient. Sequences of cloned amplicons affiliated to sequences belonging to seven Aeromonas species previously isolated from the same environment. CONCLUSIONS: The three systems used showed to be useful to describe the diversity of Aeromonas communities. However, the combined use of more than one primer set is advisable. SIGNIFICANCE AND IMPACT OF THE STUDY: The methods presented here can be applied to understand the natural pool of Aeromonas and also to monitor and control these bacteria in aquatic reservoirs.

Characterization of microbial population of 'Alheira' (a traditional Portuguese fermented sausage) by PCR-DGGE and traditional cultural microbiological methods.

AIMS: This study evaluates the microbial ecology of 'Alheira' by traditional microbiological analysis and a PCR-denaturing gradient gel electrophoresis (DGGE) protocol. METHODS AND RESULTS: Total microbial DNA from 'Alheiras' was extracted directly from the products and subjected to PCR using Eubacterial primers for 16S rDNA. The amplicons were separated by DGGE. The results demonstrated that different products of the same batch display identical profiles, whereas products from different batches of the same producer could display different DGGE profiles. 'Alheiras' from different producers were distinguishable based on the respective DGGE profiles. The obtained sequences from prevalent phylotypes affiliated with order Lactobacillales and order Bacillales and class Gammaproteobacteria. The same samples were subjected to traditional microbiological analysis. In both methods, lactic acid bacteria were dominant and were present together with other organisms, mainly members of the family Micrococcaceae. CONCLUSIONS: The approach explored in this study allowed the description of the microbial community present in 'Alheira' in particular the diversity of lactic acid bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This can be useful for the microbiological characterization of traditional products in order to develop new methods of quality control capable of supporting a standardization of the processes, while preserving their typical traits.

Tetracycline-resistance genes in gram-negative isolates from estuarine waters.

AIMS: To investigate the diversity and dissemination of tetracycline resistance genes in isolates from estuarine waters. METHODS AND RESULTS: Forty-two out of 164 multi-resistant isolates previously obtained were resistant or less-susceptible to tetracycline, as evaluated by the disc diffusion method. Minimal inhibitory concentration for resistant bacteria ranged from 16 to 256 mg l(-1). Screening of tet genes by polymerase chain reaction showed that 88% of the isolates carried at least one of the genes tested, namely tet(A) (present in 13 isolates), tet(B) (present in 13 isolates), tet(C) (present in 3 isolates), tet(D) (present in 1 isolate), tet(E) (present in 6 isolates) and tet(M) (present in 1 isolate). One isolate carried tet(A) and tet(M). To our knowledge, this study presents the first description of a tet(D) gene in Morganella morganii. Hybridization revealed that tet genes were plasmid-located in 31% of the isolates. Those isolates were included as donors in conjugation experiments and 38% transferred tetracycline resistance. CONCLUSIONS: A considerable diversity of tet genes was detected in the estuary. Frequently, these genes were associated with plasmids and could be transferred to Escherichia coli. SIGNIFICANCE AND IMPACT OF THE STUDY: The results presented provide further evidence of the role played by estuarine reservoirs in antibiotic resistance maintenance and dissemination.

Primary chemotherapy with sequential docetaxel followed by docetaxel and epirubicin in large operable breast cancer.

UNLABELLED: Primary chemotherapy is increasingly used in patients with large operable breast cancer. Docetaxel and epirubicin are the most active agents in breast cancer treatment. PURPOSE: To evaluate clinical response rate, breast conserving surgery and pathological response rate in patients with large operable breast cancer treated with docetaxel followed by docetaxel and epirubicin as primary chemotherapy. PATIENTS AND METHODS: Patients with operable breast cancer more than 3 cm in the longest diameter with T2N0, T2N1 and T3N0 disease were enrolled. Patients were treated with three cycles of docetaxel 100 mg/m2 followed by three cycles of docetaxel 75 mg/m2 and epirubicin 90 mg/m2 prior to surgery. RESULTS: Sixty-five patients were enrolled between 09/2002 and 12/2005. The median age was 48.9 years and 72.3% were premenopausal. Median tumour size was 4.26 cm, 10.8% were T3 tumours and 38.5% had clinical positive lymph nodes. Of the tumours 58.5% were grade 1/2, 33.9% ER positive and 21.5% c-erb negative. All six cycles were administered to 62 patients; six cycles were delayed and five had dose reductions. Complete clinical response occurred in 41.5% of patients and partial response in 49.2%. Breast conserving surgery was performed in 30% of patients however it was feasible in 57%. Complete pathological response occurred in both primary tumour and nodes in 28%, and in 34% just in the primary tumour. Nine percent of cases had neutropenia and 7.7% febrile neutropenia, and two cases had a hypersensitivity reaction to docetaxel. One associated treatment death occurred. CONCLUSION: Docetaxel followed by epirubicin and docetaxel as primary chemotherapy results in a high clinical and pathological response rate. The majority of adverse events were predictable and manageable.

Antibacterial activity of oxytetracycline photoproducts in marine aquaculture's water.

Oxytetracycline (OTC) is one of the most used antibiotics in aquaculture. The main concern related to its use is the bacterial resistance, when ineffective treatments are applied for its removal or inactivation. OTC photo-degradation has been suggested as an efficient complementary process to conventional methods used in intensive fish production (e.g.: ozonation). Despite this, and knowing that the complete mineralization of OTC is difficult, few studies have examined the antibacterial activity of OTC photoproducts. Thus, the main aim of this work is to assess whether the OTC photoproducts retain the antibacterial activity of its parent compound (OTC) after its irradiation, using simulated sunlight. For that, three Gram-negative bacteria (Escherichia coli, Vibrio sp. and Aeromonas sp.) and different synthetic and natural aqueous matrices (phosphate buffered solutions at different salinities, 0 and 21‰, and three different samples from marine aquaculture industries) were tested. The microbiological assays were made using the well-diffusion method before and after OTC has been exposed to sunlight. The results revealed a clear effect of simulated sunlight, resulting on the decrease or elimination of the antibacterial activity for all strains and in all aqueous matrices due to OTC photo-degradation. For E. coli, it was also observed that the antibacterial activity of OTC is lower in the presence of sea-salts, as demonstrated by comparison of halos in aqueous matrices containing or not sea-salts.

Effects of acute hypercapnia with and without acidosis on lung inflammation and apoptosis in experimental acute lung injury.

We investigated the effects of acute hypercapnic acidosis and buffered hypercapnia on lung inflammation and apoptosis in experimental acute lung injury (ALI). Twenty-four hours after paraquat injection, 28 Wistar rats were randomized into four groups (n=7/group): (1) normocapnia (NC, PaCO2=35-45 mmHg), ventilated with 0.03%CO2+21%O2+balancedN2; (2) hypercapnic acidosis (HC, PaCO2=60-70 mmHg), ventilated with 5%CO2+21%O2+balancedN2; and (3) buffered hypercapnic acidosis (BHC), ventilated with 5%CO2+21%O2+balancedN2 and treated with sodium bicarbonate (8.4%). The remaining seven animals were not mechanically ventilated (NV). The mRNA expression of interleukin (IL)-6 (p=0.003), IL-1ß (p<0.001), and type III procollagen (PCIII) (p=0.001) in lung tissue was more reduced in the HC group in comparison with NC, with no significant differences between HC and BHC. Lung and kidney cell apoptosis was reduced in HC and BHC in comparison with NC and NV. In conclusion, in this experimental ALI model, hypercapnia, regardless of acidosis, reduced lung inflammation and lung and kidney cell apoptosis.

Stroke subtypes and hypertension. Primary hemorrhage vs infarction, large- vs small-artery disease.

BACKGROUND: Hypertension is the major risk factor for stroke associated with small-artery disease and large-artery disease, but the factors behind the development of a particular stroke subtype in individual patients are not known. METHODS: We determined risk factors potentially predictive of stroke subtype in 822 of 2760 patients consecutively admitted to a primary care stroke center with (1) first-ever stroke, (2) hypertension (blood pressure >160/90 mm Hg at least twice before the stroke), and (3) no cardioembolic source. We used logistic regression analysis to delineate factors associated with ischemic (brain infarct) vs hemorrhagic (primary hemorrhage) stroke and with large- vs small-artery disease. A scoring system was elaborated on the basis of the estimated regression coefficients. Observed proportions and calculated risks were determined. RESULTS: Age greater than 67 years, cigarette smoking, hypercholesterolemia, and a family history of stroke or ischemic heart disease were independent predictors of ischemic vs hemorrhagic stroke. In women, diabetes mellitus was an additional risk factor for ischemic vs hemorrhagic stroke. Only one of 144 patients with primary hemorrhage had an ipsilateral carotid stenosis. In men with brain infarct, cigarette smoking, cardiac ischemia, and a family history of stroke or ischemic heart disease were significantly and independently associated with large- vs small-artery disease. In women with brain infarct, smoking was the only predictive factor for large- vs small-artery disease. CONCLUSION: In patients with stroke and hypertension, associated risk factors influence the subtype of stroke (hemorrhage vs brain ischemia, large- vs small-artery disease).

Predictors of stroke pattern in hypertensive patients.

BACKGROUND AND PURPOSE: Hypertension is a recognized risk factor for stroke. However, it is not clear why hypertensive patients may have different types and causes of stroke. METHODS: The possible role of coexisting factors was studied in 1057 patients with hypertension and first stroke admitted to a population-based stroke center. We used logistic regression analysis (multivariate and polychotomous) and the Lausanne Stroke Registry definitions of cerebral hemorrhage, cerebral infarction, lacunar infarction, cardioembolism and large artery disease. RESULTS: Cerebral hemorrhage was not more frequent in these hypertensive patients (111/1057 = 10.5%) than in the total population of the registry (213/2145 = 10%). Cerebral infarction was associated with age above the median (69 years), diabetes, smoking history, family history of cardiac or cerebrovascular disease, hypercholesterolemia and previous TIA. In the ischemic group (n = 946), patients suffered from a lacunar infarction in 36% of the cases, large artery disease was present in 21% of them and cardioembolism in 14.5%. Large artery disease correlated with smoking history (odds ratio: 2.14; 95% confidence intervals: 1.55-2.95) and previous TIA (OR:1.96; 95% CI:1.39-2.75). Cardioembolism correlated with age over 69 years (OR:2.13; 95% CI:1.47-3.09). In patients with previous TIA and smoking history, large artery disease was presumed in 45% of the cases (vs 21%). Patients aged over 69, suffered a cardioembolic stroke in 29% of the cases (vs 14.5%). Lacunar infarction occurred in 49% of patients aged less than 70 years when no history of smoking or previous TIA was present (vs 36%). CONCLUSION: The associations between hypertension, TIA, age and smoking history may partially explain why patients with hypertension are more likely to develop a cerebral hemorrhage, lacunar infarction, cardioembolic or a large artery disease stroke.

Rapid genotyping of the major alleles at the Duffy (FY) blood group locus using real-time fluorescence polymerase chain reaction.

The Duffy blood group system has clinical importance due to involvement in transfusion reactions and hemolytic disease of the newborn. Recently, the molecular basis of the two alleles, FY*A and FY*B (125G>A), and the mutation situated in the promoter region of the FY gene (-33T>C), have been elucidated. In order to develop an accurate, easy, and rapid genotyping method, we describe a procedure using the LightCycler. Samples from 53 Caucasian Portuguese blood donors and 7 black, healthy, European individuals were phenotyped with commercial antisera. DNA was extracted from blood samples and the relevant sequences were amplified with the same cycling conditions, using real-time polymerase chain reaction. The melting point of the FY*A allele was 63 degrees C and of the FY*B allele, 55 degrees C. The allele without mutation at the promoter region had a melting point at 64 degrees C and the FY*B silent allele at 58 degrees C. The results in Caucasian individuals were similar to those found in European and American populations. When FY genotyping techniques are necessary, the methodology described is preferable to conventional methods as it is reliable, high speed, and uses small volumes, providing a highly competitive technology for use by a routine laboratory.

Blood group antigen profile predicted by molecular biology-use of real-time polymerase chain reaction to genotype important KEL, JK,RHD, and RHCE alleles.

The most clinically important blood group systems in transfusion medicine, excluding the ABO system, are the RH, Kell, and Kidd systems. Alloantibodies to antigens of these systems may be produced following blood transfusion or during pregnancy and can result in serious hemolytic transfusion reactions and hemolytic disease of the newborn. We developed rapid and robust techniques for RHD, RHCE, KEL, and JK genotyping with the use of a real-time polymerase chain reaction instrument. Two fluorescence-based methods for the detection of amplification products were used: for KEL1/KEL2, JK1/JK2, and RHE/RHe (exon 5) we used the hybridization probes protocol; for RHC/RHc the analysis was done in sequences of exon 1 for RHC and exon 2 for RHc; and for RHD, analysis was done in sequences of intron 4, exon 7, and exon 4 pseudogene using the SYBR Green I protocol. The genotyping tests were validated with samples from 85 Caucasian Portuguese and 15 Black European blood donors. Complete phenotype-genotype correlations were obtained. The potential use of the presented methods can be predicted in clinical transfusion medicine, allowing appropriate monitoring, early intervention, and improved care. When blood group genotyping techniques are necessary, this methodology is highly competitive for a routine laboratory.

Deflocculation effects due to chemical perturbations in sequencing batch reactors.

Toxic shock-induced deflocculation was examined for activated sludge exposed to six different classes of industrially relevant chemical toxins: an electrophilic solvent (1-chloro-2,4-dinitrobenzene, CDNB), a heavy metal (cadmium), a hydrophobic chemical (1-octanol), an uncoupling agent (2,4-dinitrophenol, DNP), alkaline pH, and weakly complexed cyanide. The concentrations required to inhibit respiration by 50% were used to shock sequencing batch reactors (SBRs) containing a nitrifying (10-day solids retention time (SRT)) and a non-nitrifying (2-day SRT) biomass. Effluent total suspended solids (TSS) and soluble potassium were monitored to examine deflocculation caused by a bacterial stress response mechanism called glutathione-gated potassium efflux (GGKE). Reactors were monitored for recovery over a period of 3 SRTs or less. At the concentrations tested, CDNB, cadmium and pH 11 were found to cause significant increases in effluent TSS concentrations and showed elevated levels of potassium. In contrast, octanol, DNP and cyanide did not induce severe deflocculation and showed moderate increases in effluent potassium levels. Recovery of effluent TSS and potassium concentrations to control levels generally did not correlate, supporting the hypothesis that reflocculation requires regrowth of biomass. These results suggest that different chemicals induce deflocculation in SBRs, but deflocculation is not necessarily caused by the GGKE mechanism in all cases.

[Cerebral-cardiac embolism. Cerebrovascular-cardiac embolic stroke]. / Cardioembolismo cerebral. Acidente vascular cerebral cardioembólico.

The diagnosis of cerebral cardioembolism requires, apart from evidence of an embolic cardiopathy, a cause-effect relation to be established between the potential cardioembolic source and the occurrence of ischemic stroke. There are several arguments in favour of this reaction, namely the neurologic aspects put forward both clinicians and neuroimaging professionals, as well as the generalization of cardiologic diagnostic techniques for the etiologic investigation of ischemic stroke. Importance should be given to primary prevention of embolic cardiopathies. Oral anticoagulation should be administered in all situations where an advantage has been established when compared to antiaggregation or placebo. Cooperation between the different health structures and the different specialties probably depends on the changes in the prevalence of cerebral cardioembolism.

Impact of sampling depth and plant species on local environmental conditions, microbiological parameters and bacterial composition in a mercury contaminated salt marsh.

We compare the environmental characteristics and bacterial communities associated with two rushes, Juncus maritimus and Bolboschoenus maritimus, and adjacent unvegetated habitat in a salt marsh subjected to historical mercury pollution. Mercury content was higher in vegetated than unvegetated habitat and increased with sampling depth. There was also a significant relationship between mercury concentration and bacterial composition. Habitat (Juncus, Bolboschoenus or unvegetated), sample depth, and the interaction between both, however, explained most of the variation in composition (~70%). Variation in composition with depth was most prominent for the unvegetated habitat, followed by Juncus, but more constrained for Bolboschoenus habitat. This constraint may be indicative of a strong plant-microbe ecophysiological adaptation. Vegetated habitat contained distinct bacterial communities associated with higher potential activity of aminopeptidase, ß-glucosidase and arylsulphatase and incorporation rates of (14)C-glucose and (14)C-acetate. Communities in unvegetated habitat were, in contrast, associated with both higher pH and proportion of sulphate reducing bacteria.