Biomedical subjects

J González-López

Publications and source records attributed to J González-López.

At least 19 recordsLinked to original sources

PubMed2006

Effect of the concentration of suspended solids on the enzymatic activities and biodiversity of a submerged membrane bioreactor for aerobic treatment of domestic wastewater.

A pilot-scale submerged membrane bioreactor was used for the treatment of domestic wastewater in order to study the influence of the variations in the concentration of volatile suspended solids (VSS) on the enzymatic activities (acid and alkaline phosphatases, glucosidase, protease, esterase, and dehydrogenase) and biodiversity of the bacterial community in the sludge. The influence of VSS concentration was evaluated in two separated experiments, which were carried out in two different seasons of the year (experiment 1 through spring-summer and experiment 2 through autumn-winter). Cluster analysis of the temperature gradient gel electrophoresis (TGGE) profiles demonstrated that the community composition was significantly different in both experiments. Within the same experiment, the bacterial community experienced sequential shifts as the biomass accumulated, as shown by the evolution of the population profiles through time as VSS concentration increased. All enzymatic activities studied were significantly lower during experiment 2, except for glucosidase. Concentrations of VSS over 8 g/l induced a strong descent of all enzymatic activities, which overlapped with a significant modification of the community composition. Sequences of the major TGGE bands were identified as representatives of the Alpha-proteobacteria, filamentous bacteria (Thiotrix), and nitrite oxidizers (Nitrospira). Some sequences which were poorly related to any validated bacterial taxon were obtained.

Bacteria↗

PubMed2006

Biological nitrogen and phenol removal from saline industrial wastewater by submerged fixed-film reactor.

In this study a biological nitrogen removal process using a submerged fixed-film reactor was applied to treat industrial wastewater with phenol (1g/l), a high nitrogen concentration (0.4 g N/l) and high salinity (30 g/l). The process consisted of a pre-denitrification system with a down-flow-up-flow biofilter (two columns, each with an effective volume of 21 l) packed with clayey schists from recycled construction material. The efficiency of the system for reducing COD, phenol concentration and total nitrogen was tested under different running conditions such as influent flow (10, 12 and 15 l/d), air loading (6.8 and 13.6m(3)/m(2)h) and effluent recirculation (300%, 400%, and 600%). The system demonstrated a high capacity for reducing COD concentration (95.75+/-0.72%), independently of running conditions. The aerobic column eliminated most of the phenol in the influent. Nitrogen removal took place mainly in the anoxic column, and was conditioned by the air loading in the aerated column, owing to the dependence of nitrification on the supply of oxygen. However, this process was not able to achieve a nitrogen oxidation superior to 63%, in spite of a sufficient supply of oxygen and the diluting effect of high recirculation (600%) on the phenol concentration in the influent. In spite of the limitations observed in the process of nitrification, results for the removal of total nitrogen were as high as 83%, owing to a combination of different processes for nitrogen removal.

Biofilms↗

PubMed2006

TGGE analysis of the diversity of ammonia-oxidizing and denitrifying bacteria in submerged filter biofilms for the treatment of urban wastewater.

The spatial and temporal diversity of the bacterial community-forming biofilms in a pilot-scale submerged biofilter used for the treatment of urban wastewater was analyzed by a temperature-gradient gel electrophoresis (TGGE) approach. TGGE profiles based on partial sequence of the 16S rRNA gene showed that the community composition of the biofilms remained fairly stable along the column system and during the whole time of operation of the biofilter (more than 1 year). Community-profiling based on the amplification and separation of partial ammonia monooxygenase (amoA) and nitrous oxide reductase (nosZ) genes demonstrated that ammonia-oxidizing and denitrifying bacteria coexisted in both the anoxic and the aerated parts of the system. Several amoA and nosZ bands separated by TGGE were reamplified and sequenced, in order to further analyze the composition of these microbial communities in the biofilm. Phylogeny inferred from amoA/AmoA revealed the prevalence of Nitrosomonas species with five sequences affiliated to Nitrosomonas oligotropha, six sequences affiliated to Nitrosomonas europaea, and three sequences that showed only 75.7-76.1% identity of the DNA sequence with the closest described species (Nitrosomonas nitrosa). According to literature, this low identity value is indicative of previously undiscovered species. Eighteen new partial nosZ sequences were obtained which were mostly related to nosZ of gamma-proteobacteria (Pseudomonas) or clustered in the periphery of previously known denitrifying alpha-proteobacteria (Bradyrhizobium and Azospirillum).

Bacterial Proteins↗

PubMed2006

Influence of pesticides and herbicides presence on phosphatase activity and selected bacterial microbiota of a natural lake system.

Phosphatase activities (cell-bounded phosphatases "BP" and freely dissolved phosphatases "D P") in water samples from a natural lake "Laguna Grande" (Antequera, Málaga, Spain) amended with 50 microg/ml of selected insecticides, herbicides and fungicide captan were studied under laboratory controlled conditions (temperature and agitation). Our data show that dissolved alkaline phosphatase was the enzymatic activity that contributed in higher proportion to total lake water samples phosphatase status. The presence of organochlorinated insecticides (aldrin and lindane), organophosphorous insecticides (dimetoate, methidation and methyl-parathion), herbicide atrazine and fungicide captan significantly increased phosphatase activities after 28 days of incubation. However, these activities were not affected as a consequence of the addition of the herbicide simazine to the water samples. Heterotrophic mesophilic and psychrophilic aquatic bacteria counts as well as culturable phosphate solubilizing microorganisms, increased when the pesticides were added to lake water samples with herbicide simazine exception.

Acid Phosphatase↗

PubMed2006

Analysis of community composition of biofilms in a submerged filter system for the removal of ammonia and phenol from industrial wastewater.

The bacterial diversity of a submerged filter, used for the removal of ammonia and phenol from an industrial wastewater with high salinity, was studied by a cultivation-independent approach based on PCR/TGGE (temperature-gradient gel electrophoresis). The wastewater treatment plant (laboratory scale) combined the nitrification and denitrification processes and consisted of two separated columns (one anoxic and one aerated) connected through a valve. The spatial diversity of bacterial communities in the plant biofilms was analysed by taking samples at four different heights in the system. TGGE profiles of PCR-amplified sequences of the 16 S rRNA gene (V3-hypervariable region) showed significant variations of the bacterial diversity, mainly depending on the concentration of O(2) along the system. Several bands separated by TGGE were reamplified and sequenced, in order to explore the composition of the microbial communities in the biofilms. Most of the sequenced bands (10 out of 13) were closely related to the 16 S rRNA gene of marine alpha-proteobacteria, mainly grouping in the periphery of the genus Roseobacter. Other sequences were related to those of gamma-proteobacteria, the nitrite oxidizer Nitrospira marina and anaerobic phenol-degrading bacteria of the Desulfobacteraceae.

Ammonia↗

PubMed2005

Selection and identification of bacteria isolated from waste crude oil with polycyclic aromatic hydrocarbons removal capacities.

Fifteen bacterial strains isolated from solid waste oil samples were selected due to their capacity of growing in the presence of hydrocarbons. The isolates were identified by PCR of the 16S rDNA gene using fD1 and rD1 primers. The majority of the strains belonged to genera Bacillus, Bacillus pumilus (eight strains) and Bacillus subtilis (two strains). Besides, three strains were identified as Micrococcus luteus, one as Alcaligenes faecalis and one strain as Enterobacter sp. Growth of the above-mentioned strains in mineral liquid media amended with naphthalene, phenanthrene, fluoranthene or pyrene as sole carbon source was studied and our results showed that these strains can tolerate and remove different polycyclic aromatic hydrocarbons that may be toxic in the environment polluted with hydrocarbons. Finally, the capacity of certain strains to emulsify octane, xilene, toluene, mineral oil and crude oil, and its ability to remove hydrocarbons, look promising for its application in bioremediation technologies.

Bacillus↗

PubMed2005

Influence of inocula over start up of a denitrifying submerged filter applied to nitrate contaminated groundwater treatment.

Pure culture of denitrifying bacteria isolated from heterogeneous biofilm was applied as inocula to a submerged filter for removing nitrogen from contaminated groundwater. Five highly denitrifying bacteria were used, comparing their attachment, nitrogen-removal ability and final water quality in the start up of the system. Our experiments showed that inocula selection is the crucial step when the submerged filter is applied to obtain drinking water, since selected strains vary in their ability to colonise support material and to remove nitrogen, and in their effect on treated water quality during start up phase. Hidrogenophaga pseudoflava strain proved to be the most suitable inoculum out of the five tested, under the experimental conditions.

Bacteria↗

PubMed2005

Liberation of amino acids by heterotrophic nitrogen fixing bacteria.

Large amounts of amino acids are produced by nitrogen-fixing bacteria such as Azotobacter, Azospirillum, Rhizobium, Mesorhizobium and Sinorhizobium when growing in culture media amended with different carbon and nitrogen sources. This kind of bacteria live in close association with plant roots enhanced plant growth mainly as a result of their ability to fix nitrogen, improving shoot and root development suppression of pathogenic bacteria and fungi, and increase of available P concentration. Also, it has been strongly evidenced that production of biologically substances such as amino acids by these rhizobacteria are involved in many of the processes that explain plant-grown promotion. This paper reviews literature concerning amino acids production by nitrogen-fixing bacteria. The role of amino acids in microbial interactions in the rhizosphere and establishment of plant bacterial association is also discussed.

Amino Acids↗

PubMed2005

Inoculation of a submerged filter for biological denitrification of nitrate polluted groundwater: a comparative study.

Activated sludge from a wastewater treatment plant and pure culture of Hydrogenophaga pseudoflava were utilized for the development of a denitrifying biofilm in a submerged filter in order to remove nitrate from polluted groundwater. Nitrate removal efficiency, nitrite accumulation, turbidity, COD and faecal indicators persistence in the treated water were determined at different superficial hydraulic loading (10, 20 and 30 m(3)/m(2) d) and superficial nitrate loading rates (1, 2, 3, 6 and 9 Kg NO(3)(-)/m(2) d) in the submerged filter. The application of H. pseudoflava as inocula allowed better results in terms of system stability, higher superficial hydraulic loading and superficial nitrate loading rates (30 m(3)/m(2)d and 9 kg NO(3)(-) /m(2) d, respectively). These values improve those obtained when the system was inoculated with activated sludge. In addition, the pure microbial inocula improved design parameters and running of the process due to its biofilm homogeneity, obtaining treated water with better characteristics to its final use as drinking water than that obtained with an activated sludge inocula.

Biofilms↗

PubMed2005

Identification of bacteria isolated from an oligotrophic lake with pesticide removal capacities.

We studied the growth and capacities for pesticides removal of bacterial strains isolated from the Laguna Grande, an oligotrophic lake at the South of Spain (Archidona, Málaga). Strains were isolated from water samples amended with 10 and 50 microg/ml of nine pesticides: organochlorinated insecticides (aldrin and lindane), organophosphorous insecticides (dimetoate, methyl-parathion and methidation), s-triazine herbicides (simazine and atrazine), fungicide (captan) and diflubenzuron (1-(-4-chlorophenyl)-3-(2,6-difluorobenzoyl urea), a chitinase inhibitor. The majority of the strains belonged to the genera Pseudomonas and Aeromonas and only 9% of the total of strains were Gram positive. From all the strains isolated, only 22 showed a wide growth range in all the pesticides tested and 4 of them were chosen for pesticide removal studies. The genetic identification of these strains showed their affiliation to Pseudomonas pseudoalcaligenes, Micrococcus luteus, Bacillus sp. and Exiguobacterium aurantiacum. These last two strains were those that showed the highest pesticide removal capacities and a high bacterial growth.

Aeromonas↗

PubMed2004

Surfactant activity of a naphthalene degrading Bacillus pumilus strain isolated from oil sludge.

We studied the growth, biosurfactant activities and petroleum hydrocarbon compounds utilisation of strain 28-11 isolated from a solid waste oil. The isolate was identified as Bacillus pumilus. It grew well in the presence of 0.1% (w/v) of crude oil and naphthalene under aerobic conditions and utilised these substances as carbon and energy source. The capacity of strain 28-11 to emulsify crude oil and its ability to remove hydrocarbons looks promising for its application in environmental technologies.

Bacillus↗

PubMed2003

Influence of hydraulic loading and air flowrate on urban wastewater nitrogen removal with a submerged fixed-film reactor.

Nutrient disposal to sensitive areas, particularly nitrogen and phosphorus from wastewater treatment plants, provokes eutrophication reducing water quality. Fixed film technology is widely used for the removal of organic matter and nitrogen by the biological process of nitrification-denitrification. This paper studies a nitrification and post-denitrification lab-scale plant with a downflow aerobic submerged filter for removal of organic matter and nitrification, followed by an anoxic upflow biofilter for denitrification. Recycled construction material (clay shists) was employed as support material and methanol was used as carbon source. After 2 weeks of acclimation in which nitrification reached steady-state conditions, different hydraulic loadings (0.35-1.59 m(3)/m(2)h) and air flowrates (7.78-43.5 m(3)/m(2)h) were applied for 1 year. The highest hydraulic loading which complied with the EU regulation on nitrogen disposal was 0.71 m(3)/m(2)h (1.6 h). Hydraulic retention time (HRT), which corresponded to a nitrogen removal of 0.64 kg N/m(3) per day operating at an air flowrate of 25.6 m(3)/m(2)h. Concerning to organic matter removal efficiency, the aerobic reactor accepted a maximum chemical oxygen demand (COD) volumetric loading of 16.0 kg COD/m(3) per day with a 75% COD removal efficiency. For all the tests carried out, suspended solids (SS) concentration in the outlet water was less than 35 mg/l.

Bacteria, Aerobic↗

PubMed2003

Effect of some abiotic factors on the biological activity of Gluconacetobacter diazotrophicus.

AIMS: The effect of some abiotic factors, dryness, heat and salinity on the growth and biological activity of Gluconacetobacter diazotrophicus, and the influence of a salt stress on some enzymes involved in carbon metabolism of these bacteria is studied under laboratory conditions. METHODS AND RESULTS: Strain PAL-5 of G. diazotrophicus was incubated under different conditions of drying, heat and salinity. Cells showed tolerance to heat treatments and salt concentrations, and sensitivity to drying conditions. Higher NaCl dosage of 150 and 200 mmol l -1 limited its growth and drastically affected the nitrogenase activity and the enzymes glucose dehydrogenase, alcohol dehydrogenase, fumarase, isocitrate dehydrogenase and malate dehydrogenase. CONCLUSIONS: Gluconacetobacter diazotrophicus, despite its endophytic nature, tolerated heat treatments and salinity stress, but its nitrogenase activity and carbon metabolism enzymes were affected by high NaCl dosage. SIGNIFICANCE AND IMPACT OF THE STUDY: The investigation of the biological activity of G. diazotrophicus in response to different abiotic factors led to more knowledge of this endophyte and may help to clarify pathways involved in its transmission into the host plant.

Acetobacter↗

PubMed2002

Effects of culture conditions on the production of polyhydroxyalkanoates by Azotobacter chroococcum H23 in media containing a high concentration of alpechín (wastewater from olive oil mills) as primary carbon source.

Large amounts of homopolymers containing beta-hydroxybutyrate (PHB) and copolymers containing beta-hydroxyvalerate (P[HB-co-HV]) are produced by Azotobacter chroococcum strain H23 when growing in culture media amended with alpechín (wastewater from olive oil mills) as the sole carbon source. Copolymer was formed when valerate (pentanoate) was added as a precursor to the alpechín medium, but it was not formed with the addition of propionate as a precursor. A. chroococcum formed homo- and copolymers of polyhydroxyalkanoates (PHAs) up to 80% of the cell dry weight, when grown on NH(4)(+)-medium supplemented with 60% (v/v) alpechín, after 48 h of incubation at 100 rev min(-1) and 30 degrees C. Production of PHAs by strain H23 using alpechín looks promising, as the use of a cheap substrate for the production of these materials is essential if bioplastics are to become competitive products.

Acetates↗

PubMed2002

Effect of dissolved oxygen concentration on nitrate removal from groundwater using a denitrifying submerged filter.

A unidirectional submerged filter system was employed to purify groundwater contaminated with nitrate by biological denitrification. The influence of the concentration of dissolved oxygen (DO) in the process was tested using ethanol, methanol and sucrose as carbon sources. Inorganic-nitrogen removal, growth of the biofilm, platable denitrifying bacteria and nitrate reducing bacteria in biofilm were studied. With regard to the type of electron donor used, the presence of oxygen decreased the removal efficiency of inorganic nitrogen and caused an increase of nitrite concentration in the treated water. These negative effects depended on utilised carbon source. Biological denitrification with alcohols such as ethanol and methanol was less affected by DO than with sucrose. The development of the biofilm was also influenced by the DO concentration as excess O(2) caused reduced biofilm growth. These biofilms developed in oxygen presence had a smaller bacterial density and a lower denitrifying bacteria versus nitrate reducing bacteria ratio, which led to an unfavorable inorganic nitrogen removal and presence of nitrite in the treated water. All these effects are more pronounced when sucrose is used as carbon source.

Bacteria↗

PubMed2002

D,L-Hydantoinase activity of an Ochrobactrum anthropi strain.

AIMS: A microorganism with the ability to release methionine from D,L-(2-methylthioethyl) hydantoin (strain 245) was isolated from soil. The aim of this study was the identification of the strain and the adjustment of the conditions of growth and of the enzymatic reaction, in order to achieve high specific activities of bioconversion of the hydantoin. METHODS AND RESULTS: Strain 245 was identified as Ochrobactrum anthropi. The strain grew at alkaline pH (up to 10.0) and its hydantoinase activity was found to be inducible by the substrate D,L-(2-methylthioethyl) hydantoin. The enzyme is also alkalostable, with a pH optimum of 9.0. Under these conditions, hydantoinase activity was significantly enhanced and its half life prolonged when 200 mmol l-1 ammonium and phosphate were added. The addition of Ca2+, Na+, Cu2+, Co2+, Mg2+, Zn2+ or Fe3+ (0.5 mmol l-1) to the reaction mixture increased the hydantoinase activity of strain 245 up to tenfold after 24 h of incubation, compared with unamended controls. CONCLUSION: The adequate adjustment of some environmental parameters (pH, addition of inducer, presence of ammonium, phosphate, heavy metals and other ions) can considerably increase the D, L-hydantoinase activity of strain 245. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings reported here set up the initial conditions for a further application of strain 245 in the production of methionine from hydantoine.

Amidohydrolases↗

PubMed2001

Growth of moderately halophilic bacteria isolated from sea water using phenol as the sole carbon source.

Moderately halophilic bacteria utilizing phenol as the sole carbon source were isolated by selective enrichment from sea water. The isolate (Gram-negative motile rods) was identified as Deleya venusta. It grew well in the presence of up to 1600 mg/L of phenol and 8% NaCl under aerobic conditions. When the cells were treated with chloramphenicol prior to the addition of phenol they did not utilize added phenol, even after prolonged incubation. Thus, the enzymes necessary for phenol metabolism appeared to be inducible.

Arthrobacter↗

PubMed2000

Influence of carbon source on nitrate removal of contaminated groundwater in a denitrifying submerged filter.

The effectiveness of three selected carbon sources (sucrose, ethanol and methanol) on submerged filters for the removal of nitrate from contaminated groundwater (100mg NO3(-)/litre), was studied. Process yields, nitrite accumulation, biomass production and growth of denitrifying bacteria were compared. Process yields, represented as ratio C/N were 2.5, 1.08 and 1.1 for sucrose, ethanol and methanol assays, respectively, making sucrose the least efficient carbon source. Nitrite accumulation in treated groundwater was more notable for sucrose assays, reaching values of 5mg NO2(-)/l. However, when ethanol or methanol were used as carbon sources, nitrite accumulation in treated water was practically zero during the experiments. On the other hand, a greater biomass production was observed in these assays with sucrose, causing clogging of the filter. Higher density of denitrifying bacteria in the biofilm, observed when ethanol and methanol were amended to the influent, suggested that these carbon sources increased the denitrification activity compared with the experiments performed with sucrose. Since methanol is toxic, ethanol is considered the most suitable carbon source out of the three tested, under the experimental conditions.

Anaerobiosis↗