Performance evaluation of Moringa oleifera seeds aqueous extract for removing Microcystis aeruginosa and microcystins from municipal treated-water.

Introduction: Toxic microcystins (MCs) produced by cyanoprokaryotes -particularly by the cosmopolitan cyanobacterium Microcystis aeruginosa- pose adverse effects on aquatic organisms and their ecosystem and may also cause serious impacts on human health. These harmful monocyclic heptapeptides are the most prevalent cyanotoxins reported in freshwaters and must be eliminated for avoiding MCs release in receiving water bodies. Hence, this work aimed to test the efficacy of Moringa oleifera seeds water-based extract (MO) as a natural coagulant for removing cyanobacteria (especially M. aeruginosa), microalgae, and its associated MCs from pre-treated municipal wastewaters. Methodology: Four different MO coagulant doses (25, 50, 75 and 100 mg L-1) were investigated for cyanobacteria and microalgae removal by conventional coagulation assays and morphology-based taxonomy studies. Additionally, water turbidity and chlorophyll a (Chl a) content were also determined. Further, the presence and concentration of MCs soluble in water, remaining in the particulate fraction, and flocculated within the residual sludge were assessed using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). Results: The treatment with MO at 100 mg L-1 substantially reduced the number of cyanobacterial and microalgal species in the treated samples (average removal rate of 93.8% and 86.9%, respectively). These results agreed with a ∼44% concomitant reduction in Chl a and ∼97% reduction in water turbidity (a surrogate marker for suspended solids content). Notably, MCs concentrations in the treated water were significantly lowered to 0.6 ± 0.1 µg L-1 after addition of 100 mg L-1 MO. This value is below the WHO recommended limits for MCs presence in drinking water (<1.0 µg L-1). Discussion: The present study provides promising insights into the applicability of MO as a cost-effective, reliable, and sustainable natural coagulant, particularly for using in developing countries, to eliminate harmful cyanobacteria and cyanotoxins in municipal water treatment facilities.

Sono-Enzymatically Embedded Antibacterial Silver-Lignin Nanoparticles on Cork Filter Material for Water Disinfection.

Providing clean drinking water is a great challenge worldwide, especially for low-income countries where the access to safe water is limited. During the last decade, new biotechnological approaches have been explored to improve water management. Among them, the use of antimicrobial nanoparticles for designing innovative centralized and decentralized (point-of-use) water treatment systems for microbial decontamination has received considerable attention. Herein, antimicrobial lignin capped silver nanoparticles (AgLNP) were embedded on residual cork pieces using high-intensity ultrasound coupled with laccase-mediated grafting to obtain biofunctionalized nanomaterial. The developed AgLNP-coated cork proved to be highly efficient to drastically reduce the number of viable Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in liquid medium. Additionally, the coated-cork was characterized using FTIR-ATR spectroscopy and SEM imaging, and further used as a filter bed in a point-of-use device for water disinfection. The constructed water filtering system significantly reduced the amount of viable E. coli and resistant Bacillus cereus spores from filtered water operating at increasing residence times of 1, 4, 6, 16, 24, and 48 h. Therefore, the presented results prove that the obtained cork-based antimicrobial nanocomposite material could be used as a filtering medium for the development of water filtration system to control pathogen dissemination.

Early-stage response in anaerobic bioreactors due to high sulfate loads: Hydrogen sulfide yield and other organic volatile sulfur compounds as a sign of microbial community modifications.

In this work, the early-stage response of six lab-scale biogas bioreactors fed with different amounts of a sulfate-rich organic agro-industrial effluent was investigated. Biogas characterization, gas chromatography selective for sulfur compounds and high-throughput sequencing of 16S rRNA gene were performed. Hydrogen sulfide (H2S) yield went from transient to steady state in âˆ¼ 2 weeks for all the studied conditions. In addition, volatile sulfur compounds (VSCs), like methanethiol (MeSH) and dimethyl sulfide (DMS), were generated at high sulfate loads. Changes were evidenced in the microbial community structures, with a higher abundance of genes involved in the dissimilatory sulfate-reduction pathway in high loaded sulfate bioreactors, as determined by PICRUSt analysis. Principal component analysis (PCA) and correlation analyses evidenced strong relationships between H2S, VSCs and the microbial community. Sulfate-reducing bacteria (SRB) like Desulfocarbo, Desulfocella and Desulfobacteraceae might be possibly linked with methylation processes of H2S.

Effect of daily exposure to Pb-contaminated water on Salvinia biloba physiology and phytoremediation performance.

Lead (Pb) removal from water column was evaluated in batch experiments using naturally occurring Salvinia biloba Raddi (S. biloba) specimens collected from Middle Paraná River and exposed every 24 h to a fresh discharge of water contaminated with 2.65 ± 0.07, 12.62 ± 0.02 or 30.57 ± 0.01 mg L-1 Pb, during 10 consecutive days. S. biloba demonstrated a great ability for metal concentration-dependent Pb removal under these stressful conditions. Additionally, Pb toxicity in plants was assessed by the quantification of physiological parameters in root-like modified fronds (named "roots"), and its aerial leaf-like fronds (named "leaves") of submerged S. biloba. Photosynthetic (carotenoids, chlorophyll a, b, and total) and antioxidant pigments (anthocyanins and flavonoids), soluble carbohydrate content, and membrane stability index of both roots and leaves were affected as the metal concentration increased. In general, root deterioration was more pronounced than that in leaves, suggesting a greater implication of the former organs in Pb removal by S. biloba. All of these deleterious effects were well correlated with qualitative changes observed at plant phenotype during the assay. In conclusion, S. biloba may be considered as a water fern useful in phytoremediation strategies towards management of residual water bodies contaminated with Pb. In addition, these macrophytes could also be valuable for water biomonitoring contributing to improve risk assessments related to metal presence in wastewaters.

Key design factors affecting microbial community composition and pathogenic organism removal in horizontal subsurface flow constructed wetlands.

Constructed wetlands constitute an interesting option for wastewater reuse since high concentrations of contaminants and pathogenic microorganisms can be removed with these natural treatment systems. In this work, the role of key design factors which could affect microbial removal and wetland performance, such as granular media, water depth and season effect was evaluated in a pilot system consisting of eight parallel horizontal subsurface flow (HSSF) constructed wetlands treating urban wastewater from Les Franqueses del Vallès (Barcelona, Spain). Gravel biofilm as well as influent and effluent water samples of these systems were taken in order to detect the presence of bacterial indicators such as total coliforms (TC), Escherichia coli, fecal enterococci (FE), Clostridium perfringens, and other microbial groups such as Pseudomonas and Aeromonas. The overall microbial inactivation ratio ranged between 1.4 and 2.9 log-units for heterotrophic plate counts (HPC), from 1.2 to 2.2 log units for total coliforms (TC) and from 1.4 to 2.3 log units for E. coli. The presence of fine granulometry strongly influenced the removal of all the bacterial groups analyzed. This effect was significant for TC (p=0.009), E. coli (p=0.004), and FE (p=0.012). Shallow HSSF constructed wetlands were more effective for removing Clostridium spores (p=0.039), and were also more efficient for removing TC (p=0.011) and E. coli (p=0.013) when fine granulometry was used. On the other hand, changes in the total bacterial community from gravel biofilm were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of polymerase chain reaction (PCR)-amplified fragments of the 16S rRNA gene recovered from DGGE bands. Cluster analysis of the DGGE banding pattern from the different wetlands showed that microbial assemblages separated according to water depth, and sequences of different phylogenetic groups, such as Alpha, Beta and Delta-Proteobacteria, Nitrospirae, Bacteroidetes, Acidobacteria, Firmicutes, Synergistetes and Deferribacteres could be retrieved from DGGE bands.

Amoeba-related health risk in drinking water systems: could monitoring of amoebae be a complementary approach to current quality control strategies?

Culture-based methods for fecal indicator microorganisms are the standard protocol to assess potential health risk from drinking water systems. However, these traditional fecal indicators are inappropriate surrogates for disinfection-resistant fecal pathogens and the indigenous pathogens that grow in drinking water systems. There is now a range of molecular-based methods, such as quantitative PCR, which allow detection of a variety of pathogens and alternative indicators. Hence, in addition to targeting total Escherichia coli (i.e., dead and alive) for the detection of fecal pollution, various amoebae may be suitable to indicate the potential presence of pathogenic amoeba-resisting microorganisms, such as Legionellae. Therefore, monitoring amoeba levels by quantitative PCR could be a useful tool for directly and indirectly evaluating health risk and could also be a complementary approach to current microbial quality control strategies for drinking water systems.

Searching Simkania negevensis in environmental waters.

Simkania negevensis is an obligate intracellular bacterium grouped into the order Chlamydiales. This new amoeba-resistant bacterium represents a novel aetiologic agent of bronchiolitis and community-acquired pneumonia in both adults and children. It has been suggested that Simkania could be an ubiquitous microorganism presented in water environments. In the natural history of infections with amoeba-related bacteria encountered in aquatic habitats, the transmissions by environmental aerosols or contaminated water/air systems have been extensively recognized. Therefore, understanding the feasibility of Simkania infection by these or similar routes is relevant. In the present work, we investigated the prevalence of this novel disease-associated microorganism in water samples from different sources by real-time PCR (qPCR). Our results show Simkania detection in 5 of 185 water analyzed samples (2.7%: 2 of 88 cooling towers and 3 of 8 waste water samples). However, no Simkania was detected in a drinking water.

Prevalence study of Simkania negevensis in cooling towers in Spain.

Simkania negevensis is an obligate intracellular bacterium grouped into the order Chlamydiales. This new amoeba-resistant intracellular bacterium might represent a novel etiologic agent of bronchiolitis and community-acquired pneumonia and occurs in aquatic habitats such as drinking water and reclaimed wastewater. Another amoeba-related bacterium, Legionella pneumophila, is an etiologic agent of pneumonia transmitted by environmental aerosols or contaminated water/air cooling systems. These transmission pathways are important in the natural history of Legionellae infections and possibly other intracellular microorganisms such as Parachlamydiaceae; thus, understanding the feasibility of Simkania infection by these routes is relevant. In the present work, we investigated the prevalence of this newly identified pathogenic bacterium in cooling towers by quantitative PCR (qPCR) and its possible relationship with Legionella pneumophila co-infection. Our results show Simkania detection in 2 of 70 cooling towers analyzed. To our knowledge, this report is the first describing Simkania negevensis detection in this category of environmental water samples.

Quantification of Helicobacter pylori levels in soil samples from public playgrounds in Spain.

Helicobacter pylori are ubiquitous Gram-negative bacteria with a high estimated level of infection in the world populations, but a majority of the infected persons are asymptomatic. This pathogen has been classified by the World Health Organization as a class I carcinogen and recognized as the causal agent of most peptic ulcers and chronic gastritis that might lead to stomach cancer. Although not all the transmission pathways of these bacteria into humans have been properly identified, enough data have suggested that the oral-oral or fecal-oral ones are the main infection routes. Helicobacter pylori have been detected in non-treated water and in drinking water, which suggested that water might be an important infection source. As childhood is the critical period of infection, the aim of the present work was to examine the presence of Helicobacter pylori in soil samples from public playing areas of Spanish parks.

Detection of Catabacter hongkongensis in polluted European water samples.

The Catabacteriaceae is a new bacterial family with a unique member: Catabacter hongkongensis is a strictly anaerobic, non-sporulating, Gram-positive coccobacillus that is phylogenetically related to some clostridial clusters. Little is known of its epidemiology and environmental distribution, but the inclusion of its 16S rRNA gene sequence in GenBank has allowed it to be detected qualitatively. As a first approach for prospective surveys, a real-time polymerase chain reaction (PCR) procedure to identify C. hongkongensis has been developed. The presence of Catabacteriaceae in 29 water bodies subjected to possible human or animal impact has been investigated. Four of them were positive. The results confirm that highly polluted water can contain C. hongkongensis.