High Concentrations Of Bacteria Research Articles

Evaluation of the Impacts of Long-Term Enriched Artemia with Bacillus subtilis on Growth Performance, Reproduction, Intestinal Microflora, and Resistance to Aeromonas hydrophila of Ornamental Fish Poecilia latipinna.

The present study investigated the effect of enriched Artemia with Bacillus subtilis on growth performance, reproductive factors, proximate composition, intestinal microflora, and resistance to Aeromonas hydrophila of ornamental fish, Poecilia latipinna. Using a completely randomized design, the experiment included three groups. The first group was fed with commercial food without any probiotic. The second group was fed with unenriched Artemia, and the last group consumed long-time enriched Artemia with Bacillus subtilis. The bacteria B. subtilis with a density of 1 × 105CFUmL-1 was added daily to Artemia culture medium. The total microflora and Bacillus subtilis counts were significantly increased in enriched Artemia compared to the unenriched group (P < 0.05). In fish fed groups, growth factors did not show any significant difference (P > 0.05). The maximum relative fecundity (28.65 ± 2.52egg numberg-1), fry production (62.93 ± 4.6 individual per female), and fry survival (70.97 ± 1.56%) obtained in the third group were found to be significantly more than those in the first and the second groups. Moreover, intestinal bacterial count for Bacillus revealed that the higher concentration of bacteria was significantly related to the third group (6.24 ± 0.11logCFUg-1) (P < 0.05). Maximum protein and fat contents were observed in fish fed with Bacillus-enriched Artemia; however, no significant difference was found between control and unenriched Artemia groups (P > 0.05). The highest amount of ash was observed in fish fed with commercial food without any probiotic (P < 0.05). At the end of the feeding period, each of the three groups along with positive group (oxytetracycline 100mgkg-1 of commercial food) was exposed to A. hydrophila (BCCM5/LMG3770) bacteria intraperitoneally. Based on the results, the lowest cumulative mortality was significantly found in group three (68.75 ± 3.6%) and positive group (62.5 ± 7.0%) compared to control and unenriched Artemia groups (P < 0.05). Hence, B. subtilis with a concentration of 1 × 105CFUmL-1 during the period of Artemia culturing can improve the reproductive parameters, intestinal microflora, and resistance to pathogenic bacteria of Poecilia latipinna.

Degradation of atrazine and changes in soil biological indices throughout dendroremediation using poplars

Dendroremediation, a novel strategy for cleaning up contaminants from the environment by using special woody plant species and microbes, is a popular phytoremediation approach. It is a cost-effective and environmentally friendly method that is being increasingly adopted. Poplar species (Populus L.) have been suggested for use in remediation because of their characteristics of high biomass production, fast growth, and potential for removing pollutants. Our environment is often contaminated by toxic substances produced by human activities, and remediation of contamination is therefore a global issue. Atrazine is one of the most widely used herbicides in China. In the present study, ‘I-69/55’ poplar (P. deltoides cv. ‘I-69/55’) and hybrid poplar (Populus deltoides × nigra, DN34) grown in pots were assayed for their ability to remediate atrazine-contaminated soils. The degradation dynamics of atrazine were assessed with a high-performance liquid chromatography system using materials from a greenhouse with different rhizosphere environments. We studied the dynamic variation in microbes and microbial biomass carbon to elucidate the rhizosphere effects and mechanism of remediation of atrazine-contaminated soil by poplar. Our four treatments included a control with uncontaminated soil without a tree, atrazine pollution without a tree, atrazine pollution with ‘I-69/55’ poplar, and atrazine pollution with hybrid poplar. Hybrid poplar showed potential for remediation of atrazine-contaminated soil, and the degradation of atrazine in the rhizosphere was faster than that in non-rhizosphere soil. Atrazine significantly inhibited bacteria growth in non-rhizosphere soil. The high concentration of bacteria in the hybrid poplar rhizosphere might be key to atrazine degradation. Trends of change among fungi and actinomyces did not correspond to trends in atrazine degradation throughout the trial period. Further research is needed to predict the effects of atrazine on cultivable microorganisms in various soils. Atrazine had significant inhibitory effects on microbial biomass carbon in non-rhizosphere soil, and the rhizosphere environment of poplars enhanced the recovery of microbial biomass carbon. The potential for hybrid poplar as a dendroremediation material needs further study.

Zanahoria amarilla (Daucus carota L.) como alimento biotecnológico para vacas

Se evaluaron residuos agroindustriales de zanahoria con suero de leche para elaborar bioensilaje para vacas. Se efectuaron análisis físicos, bromatológicos y microbiológicos. Se utilizaron cuatro tratamientos (diferentes concentraciones de preparado microbiano nativo-probiótico), con 2 %, 4 %, 6 % y 8 %. El pH del proceso fue 3,9, y la temperatura, 19 °C. El tratamiento con 6 % de probiótico obtuvo los mejores resultados, con 15,39 % de proteína, 74,78 % de humedad y 14,04 % de fibra, libre de patógenos como Salmonella sp., Clostridium sp., Escherichia coli y mohos; con una mayor concentración de bacterias ácido-lácticas (2,40E+04 UFC.ml-1) y un beneficio costo de 1,33. La producción de leche en vacas Holstein mestizas alimentadas con este producto aumentó de 14,08 a 17,40 L.dia-1, por lo que se recomienda su uso como alimento suplementario.

Strusture, biomass and production of the biotic component of the ecosystem of an growing eutrophic reservoir

Using our own data and data from the literature, we assessed the total biomass of the biotic component of the ecosystem of the Ivankovo Reservoir (Upper Volga, Russia), a eutrophic reservoir which is becoming overgrown with macrophytes. The biotic component of freshwater ecosystems is formed by communities of multicellular and unicellular organisms and viruses in the water layer (plankton) and bottom sediments (benthos) and also macrophytes and autotrophic and heterotrophic organisms growing on their surface (epiphyton). The biomass of the biotic component of the Ivankovo Reservoir equaled 39,853 tons С. Plankton, benthos and macrophytes with epiphyton equaled 3.6%, 41.6% and 54.8% of the total biomass respectively. We determined the contribution of higher aquatic plants, algae, cyanobacteria, heterotrophic bacteria, viruses, protozoans, multicellular invertebrates and fish to the formation of total biomass. The largest share was taken up by higher aquatic plants (54.5%). The second largest share was taken by heterotrophic bacteria (37.4%), most of which live in the bottom sediments. The high concentration of bacteria and invertebrates in the bottom sediments indicate significant provision of the organic substrates from the water column. The biomass of fish, the highest trophic link in the reservoir, equaled 15.0% of the biomass of their potential food substrates, invertebrate animals, and 0.7% of the total biomass of the biotic component. The greater part of the autochthonous organic compound in the reservoir is formed as a result of activity of phytoplankton, which provides 69.4% of total primary production of macrophytes, phytoepiphyton, phytoplankton and phytobenthos. The total primary production during the vegetation period was approximately forty times higher than the annual production of the fish. Currently, the share in the phytoplankton of large colonial cyanobacteria not consumed by zooplankton, the share of non-heterocystic species of cyanobacteria capable of heterotrophic feeding and the share of mixotrophic flagellates is increasing. Eutrophication of the reservoir is significantly stimulated by the development of macrophytes, and, presumably, the contribution of macrophytes to the total primary production of the reservoir will continue to increase.

Mitigating airborne bacteria generations from cage-free layer litter by spraying acidic electrolysed water

Cage-free (CF) hen housing has an inherent air quality challenge of high airborne bacteria (AB) concentrations arising from hens' activities (e.g., scratching, dustbathing, and social interactions) on the litter floor. Acidic electrolysed water (AEW) is an effective disinfectant that has been widely used in the food industry. Information on AEW application to mitigate AB and litter bacteria (LB) in CF housing is lacking. This lab-scale study evaluated reduction of AB and LB by spraying AEW at three dosages (25, 50, and 75 mL [kg dry litter]−1 d−1, or designated as D25, D50, and D75, respectively), three pH values (3, 5, and 7) and two free-chlorine (FC) concentrations (100 and 200 mg L−1, or FC100 and FC200). Treatment combinations were compared with control (no spray). Three replicates were conducted for testing the effect of spray dosage and pH and four replicates for testing the effect of FC on AB and LB reduction. The results showed that a lower pH AEW yielded a greater AB and LB reduction efficiency. Spraying a lower-dosage AEW (e.g., D25) at pH of 3, 5, or 7 significantly reduced airborne total bacteria (P

A Mussel-Inspired Facile Method to Prepare Multilayer-AgNP-Loaded Contact Lens for Early Treatment of Bacterial and Fungal Keratitis.

The use of contact lenses for the early treatment of bacterial or fungal keratitis has become a new research focus. Two main requirements of the therapeutic contact lenses are antimicrobial ability and visible light transmittance. Silver nanoparticles (AgNPs), as a nonspecific antimicrobial component, have been loaded onto contact lenses for the treatment of bacterial and fungal keratitis. Recently, it was reported that, via a simple immersion method, AgNPs can be synthesized and fixed onto the surface of polydopamine (PDA)-coated materials. However, in this study, we found that the above traditional method has the disadvantages of poor AgNP loading and low visible light transmittance, which could be induced by a limited amount of phenolic hydroxyl groups on and second oxidation of the PDA coating, respectively. To overcome these disadvantages, in this paper, we provided a facile and novel method to robustly bind multilayer-AgNPs on contact lens surfaces by using dopamine as a reducing agent and bioglue. In comparing with the monolayer-AgNP-loaded contact lenses fabricated by the traditional method, the multilayer-AgNP-loaded contact lenses had excellent antimicrobial ability and better visible light transmittance. Moreover, the multilayer-AgNP-loaded contact lens had low cytotoxicity to human corneal epithelial cells and anti-inflammation properties. Furthermore, the shortcoming of decreasing visible light transmittance induced by excess adherence of AgNPs on the multilayer-AgNP-loaded contact lens was alleviated by decreasing the size of AgNPs through altering the concentration of dopamine and AgNO3. Contact lenses loaded with small AgNPs (Ag@PDA-2.5, diameter ≈ 25-50 nm) had approximately the same Ag+ release and antimicrobial abilities, but significantly better visible light transmittance and anti-inflammatory properties than the contact lenses loaded with large AgNPs (Ag@PDA-5, diameter ≈ 50-75 nm). After that, in vivo testing indicated the promising therapeutic strategy of multilayer-AgNP-loaded contact lenses (Ag@PDA-2.5) for early bacterial keratitis and fungal keratitis. In addition, PDA coating could provide reactive sites to immobilize other biomolecules or drugs on this multilayer-AgNP-loaded contact lens for further combination therapies in treating bacterial or fungal keratitis. Finally, the stability of the visible light transmittance of the multilayer-AgNP-loaded contact lens was detected. The visible light transmittance of Ag@PDA-2.5 was weakened after being cultured with an extremely high concentration of bacteria, while it was stable in the moderate work environment. Though PDA coating had been wildly used to modify implantation devices, however, few studies about PDA coating modified contact lenses have been reported so far. Therefore, this research also provides an important basis for using PDA coating to modify a therapeutic contact lens.

Behaviour during transportation predicts stress response and lower airway contamination in horses.

This study aimed to document the effects of an eight hour journey on behavioural, clinical, haematological, environmental and respiratory parameters, and to identify possible associations between factors. Twelve horses underwent clinical examination, respiratory endoscopy with tracheal wash (TW) aspiration, and collection of venous and arterial blood before (BJ) and after the journey (AJ). TW were submitted for conventional quantitative bacteriological evaluation and genetic microbiome analyses. Behaviour was assessed in stables prior to transportation and throughout the journey. Transportation caused mild, but significant, effects on fluid and electrolyte balance and an acute phase response, characterized by neutrophilia, hyperfibrinogenaemia and hyperglobulinaemia. The proportion of neutrophils in TW, tracheal mucus and TW bacterial concentration was increased AJ, with preferential replication of Pasteurellaceae. Horse behaviour en route predicted clinical and respiratory outcomes. The frequency of stress related behaviours was greatest in the first hour of the journey, and balance-related behaviours were most common in the final hour of the journey. Horses which lowered their heads less frequently en route and showed more stress-related behaviours had higher physiological stress (serum cortisol and heart rate on arrival), increased tracheal mucus and inflammation scores, and higher TW bacterial concentration AJ (P<0.05). Six horses with abnormal lung auscultation AJ proved to have had higher tracheal inflammation scores at preloading (P = 0.017), an overall higher concentration of bacteria in their TW (P = 0.013), and an increased percentage of neutrophils in TW at five days AJ (P = 0.003) in comparison to the other horses. While transport-related health problems are multifactorial, clinical examination, including auscultation and endoscopic inspection of the lower respiratory tract before and after journey, and behavioural observation en route may identify animals at increased risk of transport associated respiratory disease.

Hydrogeological characterization and environmental effects of the deteriorating urban karst groundwater in a karst trough valley: Nanshan, SW China

The unique hydrogeology of karst makes the associated groundwater respond quickly to rainfall events and vulnerable to anthropogenic pollutions. In this study, high-frequency monitoring of spring discharge, temperature, electrical conductivity (EC) and pH, along with monthly hydrochemical and microbial analyses, was undertaken at the outlet of Laolondong karst underground river in Nanshan, southwestern China. The aim was to explore the environmental effects of the catchment’s urban area on the karst groundwater resources. The monitoring data of a tracer test and the response of discharge to rainfall events demonstrate that conduits and narrow fissures coexist in the Laolongdong karst aquifer. The EC, Na+, Cl− and SO42− values (840 μS/cm, 33.7, 38.6 and 137.2 μg/L, respectively), along with high concentrations of fecal coliform bacteria, at the outlet indicate considerable urban pollution in this area. The contaminants sulfate and nitrate showed different relationships with discharge and EC in different stages of a rainfall event. This behavior provided information about aquifer structure and the influence of transport properties. Meanwhile, the hydrological processes of groundwater flow could be modified by urbanization and result in increasing magnitude of urban floods in the underground river. In addition, sulfuric and nitric acids introduced by urbanization not only impact the karst groundwater quality, but also result in a significant perturbation to the carbon cycling system in the karst area.

Assessment of Indoor Microbial Quality of Library’s Premise: Case of Central Library of the University of Yaound&amp;#233; I

Background: Good indoor air quality is important for human health and comfort, because people spend a most of their time within buildings. Microbial pollution is a key element of indoor air pollution. Bacteria and fungi growing indoors when sufficient moisture is available usually cause indoor air pollution. Methods: This study was conducted to assess the microbial concentration and to identify the main bacteria and fungi in the indoor environment of Central Library of the University of Yaounde I. A total of 76 samples were taken from indoor air, surfaces and mouldy books. Bioaerosol sampling and air concentration were made by passive air sampling technique using petri dishes containing different culture media and exposed for 30, 60 and 90 min in the morning and afternoon. Sampling of surfaces and mouldy books were made by rubbing using sterile swab. The identification of the isolated microorganisms was based on macroscopic, microscopic and biochemical characters. Results: The concentrations of bacteria and fungi in the indoor environment of Central Library of the University of Yaounde I ranged between 747 and 2324 CFU/m for the air and 40 and 500 CFU/cm2 for surfaces. In the examined area, the predominant culturable species of microflora were members of the following bacteria genera; Bacillus spp, Staphylococcus spp, Micrococcus spp, Pseudomonas spp, Rhodococcus spp, Enterobacter spp, Klebsiella spp and Escherichia spp and fungi; Aspergillus spp, Penicillium spp, Curvularia spp, Mucor spp, Cladosporium spp, Candida spp Rhodotorula spp, Fusarium spp, Trichophyton spp, Acremonium spp, Aureobasidium spp, Rhizopus spp and Chrysonilia spp. Conclusion: High concentrations of bacteria and fungi were observed in the central library of the University of Yaounde I. Precautions and safety measures should be taken to reduce microbial pollution at universities libraries by improving libraries ventilation and disinfection.

A Nonparametric Projection-Based Estimator for the Probability of Causation, with Application to Water Sanitation in Kenya

Current estimation methods for the probability of causation (PC) make strong parametric assumptions or are inefficient. We derive a nonparametric influence-function-based estimator for a projection of PC, which allows for simple interpretation and valid inference by making weak structural assumptions. We apply our estimator to real data from an experiment in Kenya, which found, by estimating the average treatment effect, that protecting water springs reduces childhood disease. However, before scaling up this intervention, it is important to determine whether it was the exposure, and not something else, that caused the outcome. Indeed, we find that some children, who were exposed to a high concentration of bacteria in drinking water and had a diarrheal disease, would likely have contracted the disease absent the exposure since the estimated PC for an average child in this study is 0.12 with a 95% confidence interval of (0.11, 0.13). Our nonparametric method offers researchers a way to estimate PC, which is essential if one wishes to determine not only the average treatment effect, but also whether an exposure likely caused the observed outcome.

ISOLATION OF EXTENDED-SPECTRUM BETA-LACTAMASES PRODUCING STRAINS ON EFFLUENT OF STATE HOSPITAL FROM BOA VISTA-RR

The extended spectrum beta-lactamase (ESBL) producing bacteria are widespread in hospital environments. The incorrect disposal of clinical waste in hospital effluents, allows them to present high concentrations of bacteria with antimicrobial resistance profiles that present an environmental risk to the extent that they allow the dissemination. This research covers the characterization of the presence of multi-resistant antimicrobial bacteria in strains isolated from hospital effluents, whose associated risks include the spread of pathogenic microorganisms in the environment. To complete this research, the proposed objectives were: characterization of the hospital effluent strains generated by the General Hospital of Roraima (GHR) and research of the resistance genes responsible for ESBL coding and hydrolysis to the antimicrobials of the class of cephalosporins, penicillins and monobactams. Samples were collected from the hospital septic tank from June 2014 to June 2016, submitted to molecular identification for the detection of genes through the polymerase chain reaction (PCR). The results showed the presence of ESBL in all of the collected tanks and a multi-resistance profile. ESBL genes were identified on isolated frequencies and they were combined. The results indicated the widespread dissemination of the ESBL genes in the GHR effluent.

Dynamic cellular complexity of anoxygenic phototrophic sulfur bacteria in the chemocline of meromictic Lake Cadagno.

The meromictic Lake Cadagno is characterized by a compact chemocline with high concentrations of anoxygenic phototrophic purple sulfur bacteria (PSB) and green sulfur bacteria (GSB). The co-occurrence of phylogenetically distant bacterial groups such as PSB and GSB in the same ecological niche, makes the chemocline of Lake Cadagno an ideal system for studying the conditions and consequences of coexistence of photosynthetic bacteria populations. In this study, we applied flow cytometry (FCM) as a fast tool to identify metabolic changes due to the production and consumption of inclusion bodies such as sulfur globules (SGBs), and follow population dynamics of closely related anoxygenic photosynthetic sulfur bacteria in their natural environment. Large-celled PSB Chromatium okenii and GSB Chlorobium populations were reliably separated and identified due to differences in auto-fluorescence and cell size. Moreover, we showed that these dominant taxa share the same ecological niche over seasonal periods. Taking advantage of FCM detection of dynamic cellular complexity variation during phases of photosynthetic activity, we identified an unexpected alternation in PSB versus GSB metabolic activity, indicating dynamic interspecific interactions between these two populations.

Blooms of bryozoans and epibenthic diatoms in an urbanized sandy Beach (Balneário Camboriú - SC - Brazil): dynamics, possible causes and biomass characterization

Abstract Balneário Camboriu (SC - Brazil) is a touristic city where the disordered growth of the urban population and the implementation of coastal works without proper evaluation generated environmental impacts and affected the sanitary quality of water and sediment of Camboriu River and marine adjacent area. One of the most recent and alarming phenomena observed are the blooms of invasive bryozoans (Arboscuspis bellula and Membraniporopsis tubigera) associated with epibenthic diatoms (Amphitetras antediluviana and Biddulphia biddulphiana). Several clues associate these phenomena, started in 2003, with the excess of nutrients and organic matter in the Camboriú cove and large coastal works such as dredging, landfills and construction of jetties, leading to changes in benthic ecological structure. Being an aesthetic and environmental health problem, the concern of the scientific community and government agencies intensified as the occurrences become more frequent and persistent. This research addresses this issue through environmental and experimental studies. Samplings of the benthic material collected by boat and diving, and blooms monitoring were the environmental approach. The laboratory work included the algal isolation and culture, in addition to growth conditions assessment and chemical biomass analysis. Monitoring data showed a seasonal trend in the blooms, with more conspicuous events in warmer months. Diatoms increase in abundance in colder months and bryozoans in the warmer ones. The diatom A. antediluviana, predominant in the blooms, grew satisfactorily in laboratory cultivation, showing better growth in media with higher concentrations of silicate and phosphate. Bryozoans showed slow growth in laboratory conditions. The deposited material collected in the environment showed low concentrations of saturated fatty acids, but the high biomass suggest a possible use for biofuels production. Biomass samples dominated by bryozoans showed moderate antimicrobial activity against Klebsiella pneumoniae. The explanation for the occurrence of these blooms are still inconclusive, but there is considerable evidence that it is a synergistic effect between the high concentration of bacteria and organic debris in the water related to local pollution and the elimination of natural competitors by coastal works.

Modeling of Cd adsorption to goethite-bacteria composites

The accurate modeling of heavy metal adsorption in complex systems is fundamental for risk assessments in soils and associated environments. Bacteria-iron (hydr)oxide associations in soils and sediments play a critical role in heavy metal immobilization. The reduced adsorption of heavy metals on these composites have been widely reported using the component additivity (CA) method. However, there is a lack of a mechanism model to account for these deviations. In this study, we established models for Cd adsorption on goethite-Pseudomonas putida composites at 1:1 and 5:1 mass ratios. Cadmium adsorption on the 5:1 composite was consistent with the additivity method. However, the CA method over predicted Cd adsorption by approximately 8% on the 1:1 composite at high Cd concentration. The deviation was corrected by adding the site blockage reactions between P. putida and goethite. Both CA and “CA-site masking” models for Cd adsorption onto the composites were in line with the ITC data. These results indicate that CA method in simulating Cd adsorption on bacteria-iron oxides composites is limited to low bacterial and Cd concentrations. Therefore the interfacial complexation reactions that occur between iron (hydr)oxides and bacteria should be taken into account when high concentrations of bacteria and heavy metals are present.

Bacterial Lipopolysaccharide Destabilizes Influenza Viruses.

Depending on the specific viral pathogen, commensal bacteria can promote or reduce the severity of viral infection and disease progression in their hosts. Influenza A virus (IAV) has a broad host range, comprises many subtypes, and utilizes different routes of transmission, including the fecal-oral route in wild birds. It has been previously demonstrated that commensal bacteria can interact with the host's immune system to protect against IAV pathogenesis. However, it is unclear whether bacteria and their products may be interacting directly with IAV to impact virion stability. Herein we show that gastrointestinal (GI) tract bacterial isolates in an in vitro system significantly reduce the stability of IAV. Moreover, bacterial lipopolysaccharide (LPS), found on the exterior surfaces of bacteria, was sufficient to significantly decrease the stability of both human and avian viral strains in a temperature-dependent manner, including at the relevant temperatures of their respective hosts and the external aquatic habitat. The subtype and host origin of the viruses were shown to affect the extent to which IAV was susceptible to LPS. Furthermore, using a receptor binding assay and transmission electron microscopy, we observed that LPS binds to and alters the morphology of influenza virions, suggesting that direct interaction with the viral surface contributes to the observed antiviral effect of LPS on influenza. IMPORTANCE Influenza A virus (IAV), transmitted primarily via the fecal-oral route in wild birds, encounters high concentrations of bacteria and their products. Understanding the extent to which bacteria affect the infectivity of IAV will lead to a broader understanding of viral ecology in reservoir hosts and may lead to insights for the development of therapeutics in respiratory infection. Herein we show that bacteria and lipopolysaccharide (LPS) interact with and destabilize influenza virions. Moreover, we show that LPS reduces the long-term persistence and freeze-thaw stability of IAV, which is important information for modeling the movement and emergence of novel strains from animal hosts. Our results, demonstrating that the subtype and host origin of a virus also influence its susceptibility to LPS, raise key questions about the fitness of viruses in reservoir hosts, their potential to transmit to humans, and the importance of bacterial-viral interactions in viral ecology.

Interspecific Potato Breeding Lines Display Differential Colonization Patterns and Induced Defense Responses after Ralstonia solanacearum Infection.

Potato (Solanum tuberosum L.) is one of the main hosts of Ralstonia solanacearum, the causative agent of bacterial wilt. This plant pathogen bacteria produce asymptomatic latent infections that promote its global spread, hindering disease control. A potato breeding program is conducted in Uruguay based on the introgression of resistance from the wild native species S. commersonii Dun. Currently, several backcrosses were generated exploiting the high genetic variability of this wild species resulting in advanced interspecific breeding lines with different levels of bacterial wilt resistance. The overall aim of this work was to characterize the interaction of the improved potato germplasm with R. solanacearum. Potato clones with different responses to R. solanacearum were selected, and colonization, dissemination and multiplication patterns after infection were evaluated. A R. solanacearum strain belonging to the phylotype IIB-sequevar 1, with high aggressiveness on potato was genetically modified to constitutively generate fluorescence and luminescence from either the green fluorescence protein gene or lux operon. These reporter strains were used to allow a direct and precise visualization of fluorescent and luminescent cells in plant tissues by confocal microscopy and luminometry. Based on wilting scoring and detection of latent infections, the selected clones were classified as susceptible or tolerant, while no immune-like resistance response was identified. Typical wilting symptoms in susceptible plants were correlated with high concentrations of bacteria in roots and along the stems. Tolerant clones showed a colonization pattern restricted to roots and a limited number of xylem vessels only in the stem base. Results indicate that resistance in potato is achieved through restriction of bacterial invasion and multiplication inside plant tissues, particularly in stems. Tolerant plants were also characterized by induction of anatomical and biochemical changes after R. solanacearum infection, including hyperplasic activity of conductor tissue, tylose production, callose and lignin deposition, and accumulation of reactive oxygen species. This study highlights the potential of the identified tolerant interspecific potato clones as valuable genetic resources for potato-breeding programs and leads to a better understanding of resistance against R. solanacearum in potato.

Nutrients and Phytoplankton in a Shallow, Hypereutrophic Urban Lake: Prospects for Restoration

University Lake, a shallow, artificial, urban lake adjacent to the campus of Louisiana State University, has a long history of water quality problems, including algal blooms, fish kills, and high concentrations of fecal indicator bacteria. Periodic dredging of the lake is necessary to prevent its return to swampland. This study was undertaken to elucidate the roles of allochthonous versus autochthonous nutrients as causes of water quality problems in the lake, with the expectation that this information would help identify strategies for lake restoration. Photosynthetic rates and concentrations of inorganic nutrients and phytoplankton pigments were measured over a period of one year. More than 90% of the chlorophyll a (chl a) in the lake was accounted for by Chlorophyceae, Cyanophyceae, and Bacillariophyceae. Concentrations of chl a, which averaged 75 μg L−1, fluctuated weekly during dry weather by as much as a factor of four. Phytoplankton growth rates were about 30% higher 1–2 days after rain events than after periods of dry weather, the implication being that allochthonous nutrient loading has a significant effect on the dynamics of the phytoplankton community in the lake. Therefore, dredging of sediments will likely produce no long-term improvement in water quality. More than 100 storm drains currently discharge into the lake, and diversion of those drains may be the most cost-effective strategy for effecting a long-term improvement in water quality.

Development and application of the compression frictional treatment method for sterilizing and valorizing organic waste

ABSTRACTConfined animal feeding operations are producing large amounts of organic waste with large fractions being mixtures of manure and sawdust. On one hand, the inhomogeneity of the material and the high water content restrict the optimal application of thermal treatment methods. On the other hand, the high concentration of bacteria in these mixed waste streams is an issue of concern. This study introduces a novel process for treating manure and woody biomass mixtures and upgrading them into valuable products. It is defined as compression frictional treatment (CFT) and takes place continuously in a rotary compression unit. Fresh poultry droppings and fresh anaerobic digester offal from a cattle feedlot were processed by means of CFT. Moisture was decreased by 52% and heating value was increased by 27% for treated poultry litter. The corresponding values were 63% moisture decrease and 25% increase for the heating value of cattle manure. On the aspect of bacteria reduction, the Escherichia coli and the Enterobacteriaceae family of bacterium were reduced by 94% and 91%, respectively.

ANALYSIS OF PARS PLANA VITRECTOMY INCISIONS USING LIVE BACTERIA

To analyze small gauge pars plana vitrectomy sclerotomies using live bacteria transformed with green fluorescent protein (GFP). Twenty-eight human cadaver eyes were specially harvested for this study. Small gauge vitrectomy was performed on each eye and the wounds were closed with various techniques (sutured, sutureless, and cauterization). Live Staphylococcus epidermidis that has been transformed with a green fluorescent protein was applied to the overlying conjunctival surface. Analysis of all vitreous samples was analyzed with confocal laser microscopy to identify the presence of bacteria. All wounds were analyzed histopathologically. A high concentration of bacteria was noted in 2 of 3 eyes in the sutureless, 23-G perpendicular incision group postinoculation. There were no bacteria detected in any postvitrectomy sample that were closed with cautery or a beveled incision. No bacteria were found in postvitrectomy samples of sutureless 27-G perpendicular incisions and sutureless 27-G beveled incisions. Finally, there were no bacteria detected in both eyes with 23-G perpendicular incisions that had a partial air-fill. Live bacteria can be effectively used to analyze wound integrity. Closing sclerotomy sites with cautery proved effective in a model using fresh, human cadaver eyes. 27-G perpendicular incisions may be just as competent as 27-G beveled incisions.

Wheat germ agglutinin and Lens culinaris agglutinin sensitized anisotropic silver nanoparticles in detection of bacteria: A simple photometric assay

Efficacy of anisotropic silver nanoparticles sensitized with wheat germ agglutinin (WGA) and Lens culinaris agglutinin (LCA) was studied for detection of Staphylococcus aureus and Escherichia coli. It was demonstrated that interaction of these nanoparticles with bacteria stabilizes them and prevents their aggregation upon addition of sodium chloride; such stabilization depends on bacteria concentration. High concentration of bacteria results in higher stabilization whereas low concentration leads to aggregation of nanoparticles. Optical changes as a result of aggregation correlate with bacteria concentration. The developed approach allows the detection of Gram-positive bacteria (S.aureus) with the lowest detectable concentration of 103 cells/mL and Gram-negative bacteria (E. coli) with the lowest detectable concentration of 3 × 103 cells/mL using WGA-sensitized nanoparticles. In the case of LCA-sensitized nanoparticles the lowest detection was 5 × 103 cells/mL for S. aureus and 5 × 104 cells/mL for E. coli.