Metabolic Activity Of Bacteria Research Articles

Microbial populations and activities of mangrove, restinga and Atlantic forest soils from Cardoso Island, Brazil

Mangroves provide a distinctive ecological environment that differentiates them from other ecosystems. This study deal to evaluate the frequency of microbial groups and the metabolic activities of bacteria and fungi isolated from mangrove, restinga and Atlantic forest soils. Soil samples were collected during the summer and winter at depths of 0-2, 2-5 and 5-10 cm. Except for fungi, the counts of the total, sporulating, Gram-negative, actinomycetes, nitrifying and denitrifying bacteria decreased significantly in the following order: Atlantic forest >mangrove > restinga. The counts of micro-organisms decreased by 11 and 21% from the surface to the 2-5 and 5-10 cm layers, but denitrifying bacteria increased by 44 and 166%, respectively. A larger growth of micro-organisms was verified in the summer compared with the winter, except for actinomycetes and fungi. The average frequency of bacteria isolated from mangrove, restinga and Atlantic forest soils was 95, 77 and 78%, and 93, 90 and 95% for fungi, respectively. Bacteria were amylolytic (33%), producers of acid phosphatase (79%) and solubilizers (18%) of inorganic phosphate. The proportions of fungi were 19, 90 and 27%. The mangrove soil studied had higher chemical characteristics than the Atlantic forest, but the high salinity may have restricted the growth of microbial populations. Estimates of the microbial counts and activities were important to elucidate the differences of mangrove ecosystem from restinga and Atlantic forest.

Effect of N-hydroxyurea, mitomycin C and actinomycin D on tumour formation on the leaves of Kalanchoe daigremontiana

The leaves of <em>Kalanchoe daigremontiana</em> wounded and infected with <em>Agrobacterium tumefaciens</em> were treated with single doses of inhibitors (hydroxyurea - 190, mitomycin - 0.5, actinomycin - 2 µ,g per leaf). After delaying the time' of dosage of inhibitors during five days after inoculation, changes in susceptibility of the system to antitumorous activity of analysed compounds were observed. In several hours after inoculation (period of the bacteria metabolic activity in wounds) all the inhibitors prevent strongly the tumour formation. At the time between 14 and 72 hours after inoculation, including the phase of tumour induction, the system becomes sensitive to the DNA synthesis inhibitors, particularly hydroxyurea. The intensified action of actinomycin appears again only about 60 hours after inoculation and lasts till the end of experiment (the initiation of the transformed plant cell proliferation). According to the literature the antitumorous effect of inhibitors could be connected with their action on the bacteria metabolism inside the host tissue. The activities of hydroxyurea and mitomycin in the second period correspond with the intensive DNA synthesis in plant cells, which is induced by wounding. The effect of actinomycin D in 60 hours after inoculation could depend upon the inhibition of the proliferation of the transformed host cells.

Acoustic Emission Signal of Lactococcus lactis before and after Inhibition with NaN3 and Infection with Bacteriophage c2

The detection of acoustic emission (AE) from Lactococcus lactis, ssp lactis is reported in which emission intensities are used to follow and define metabolic activity during growth in nutrient broths. Optical density (OD) data were also acquired during L. lactis growth at 32°C and provided insight into the timing of the AE signals relative to the lag, logarithmic, and stationary growth phases of the bacteria. The inclusion of a metabolic inhibitor, NaN3, into the nutrient broth eliminated bacteria metabolic activity according to the OD data, the absence of which was confirmed using AE data acquisition. The OD and AE data were also acquired before and after the addition of Bacteriophage c2 in L. lactis containing nutrient broths during the early or middle logarithmic phase; c2 phage m.o.i. (Multiplicity of infection) was varied to help differentiate whether the detected AE was from bacteria cells during lysis or from the c2 phage during genome injection into the cells. It is proposed that AE measurements using piezoelectric sensors are sensitive enough to detect bacteria at the amount near 104 cfu/mL, to provide real time data on bacteria metabolic activity and to dynamically monitor phage infection of cells.

Metabolism in bacteria at low temperature: A recent report

The adaptability of bacteria to extreme cold environments has been demonstrated from time to time by various investigators. Metabolic activity of bacteria at subzero temperatures is also evidenced. Recent studies indicate that bacteria continue both catabolic and anabolic activities at subzero temperatures. Implications of these findings are discussed.

Comparison of biodegradability of various polypropylene films containing pro-oxidant additives based on Mn, Mn/Fe or Co

The biodegradability of two polypropylene films with low content of ethylene (a statistical copolymer (PPs) and a block copolymer (PPb) with balanced additions of phenolic antioxidant and pro-oxidants based on Mn, Mn/Fe or Co was studied. Abiotic pre-treatments by accelerated artificial photooxidation and thermooxidation representing about 3–4 years of outdoor weathering, including 3–4 months of exposure to daylight and 3 years in soil were followed by FTIR and SEC measurements. When a controlled oxidation was reached in the films, they were inoculated, in a second step, with the strain Rhodococcus rhodochrous in mineral medium and incubated up to 180 days. The metabolic activity of bacteria was evaluated by measuring ATP content, ADP/ATP ratio and cell viability. Complementary 1H NMR experiments were conducted on the incubation media, with and without cells, in order to monitor the consumption of soluble compounds excreted from the oxidized polymers by R. rhodochrous cells. The main conclusions are that the Co derivatives (with Co content ≥ 150 ppm) must be considered toxic for R. rhodochrous. PP films containing pro-oxidants based on Mn and Mn + Fe give positive results for the biotest (low ADP/ATP ratio, post-development in Petri dishes). However the biodegradability of oxidized PP films is less efficient in comparison to oxidized PE films (see paper published in this journal). This observation may be correlated with the accumulation in the incubation media of oxidized oligomers that cannot be metabolized rapidly by the bacterial cells and/or by the residual crystallinity of PP derivatives.

On-line detection of toxic components using a microbial fuel cell-based biosensor

Safe drinking water without toxic chemicals is crucial for people's health. A recently developed sensor for the detection of toxic components in water is the microbial fuel cell (MFC)-based biosensor. In this biosensor, substrate consumption rate and metabolic activity of bacteria are directly related to the electric current. A reduction in current under otherwise similar conditions is an indication of toxic inhibition. Under steady state conditions, current can be described by the Butler–Volmer–Monod (BVM) model. Knowing which parameters of this model change under toxic contamination can give an indication on the type of toxicity. The model requires that the substrate concentration is known. It is shown in this paper that is not possible to estimate both the substrate concentration as well as the BVM parameters on-line from current data at constant overpotential. However, it appears that substrate concentration and substrate consumption rate can be estimated on-line, and that after a linear reparametrization the BVM parameters can be estimated by ordinary least-squares techniques from a polarization curve that is generated as soon as a suspect change in current occurs. Analysis shows that a weighted least-squares method is necessary to secure a good fit at the overpotentials where current is most sensitive to changes in kinetic parameters. A protocol for on-line detection of toxicity and for detection of the type of kinetic inhibition is provided.

Viscosity dictates metabolic activity of Vibrio ruber.

Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment.

EFFECTS OF SHEWANELLA ALGAE ON CORROSION OF Zn-Al-Cd ANODE

Shewanella is a typical iron-reducing bacteria which can reduce insoluble ferric iron to soluble ferrous iron and consume oxygen, being considered as the reasons of corrosion inhibition. The main study on Shewanella algae (SA) is the degradation of environmentally harmful organic compounds and heavy metals, and there are very few reports on the interaction of metal corrosion and SA. In this paper, the bacteria isolated from yellow rust layer were identified as SA by using molecular biology techniques. The growth curve of SA was determined with spectrophotography. The results showed that the growth curve was divided into three phases: exponential growth phase, steady phase and decay phase. The effects of SA on corrosion of Zn-Al-Cd anode were investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and fluorescence microscopy (FM). The results showed that corrosion potential for samples exposed to the culture medium containing SA was higher than that for samples exposed to the sterile culture medium during the whole experiment. R-ct value in the culture medium containing SA was much greater than that of anode in the sterile culture medium. The bacteria could inhibit the corrosion of the specimen. The reason was that a biofilm layer was formed on the sample surface and the oxygen was consumed through the metabolic activities of bacteria in the culture medium containing bacteria. The biofilm layer was formed on the 5th day in the culture medium containing bacteria. While in bacteria-free system, obvious corrosion pits and white corrosion products were seen on the sample surface. The complete biofilm was formed on 7th day, and it detached from the sample on 11th day because of the exhaustion of nutrients and oxygen, showing that the biofilm formation had a great relationship with the presence of nutrients and oxygen.

Inhibition ofStreptococcus gordoniiMetabolic Activity in Biofilm by Cranberry Juice High-Molecular-Weight Component

Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM on Streptococcus gordonii metabolic activity and biofilm formation on restorative dental surfaces. We found that the NDM selectively inhibited metabolic activity of S. gordonii, without affecting bacterial viability. Inhibiting the metabolic activity of bacteria in biofilm may benefit the health of the oral cavity.

Assembléias de foraminíferos e tecamebas associadas a análises sedimentológicas e microbiológicas no delta do rio Paraíba do Sul, Rio de Janeiro, Brasil

Três setores ambientais foram definidos no delta do rio Paraíba do Sul, localizado no norte do estado do Rio de Janeiro, com base em assembléias de foraminíferos e tecamebas além de análises sedimentológicas e microbiológicas. A análise em DCA demonstrou que o carbono bacteriano e a concentração de sedimentos finos foram as análises ambientais mais influentes na distribuição das assembléias. Setor I - composto dominantemente por espécies de foraminíferos aglutinantes, índice de diversidade variável, atividade metabólica bacteriana em aero e anaerobiose, sedimentação areno-siltosa; Setor II - composto por assembleias mistas de foraminíferos e de tecamebas, apresentando os maiores valores de diversidade, atividade metabólica bacteriana em algumas regiões em aerobiose e sedimentação arenosa pobremente selecionada; Setor III - caracterizado pela ocorrência de somente tecamebas, com altas concentrações de carbono bacteriano e sedimentação dominantemente arenosa pobremente selecionada. Este setor representou o ambiente fluvial. Os resultados refletiram o comportamento hidrodinâmico da área e podem ser utilizados em estudos para diagnóstico ambiental e vulnerabilidade deste ecossistema, além de poder ser utilizados como base em estudos paleoambientais do delta.

Reverse transcription quantitative PCR revealed persistency of thermophilic lactic acid bacteria metabolic activity until the end of the ripening of Emmental cheese

For Emmental manufacture two kinds of adjunct culture are added: (i) thermophilic lactic acid bacteria (starters) such as Lactobacillus helveticus (LH), and Streptococcus thermophilus (ST) growing the first day of the manufacture and (ii) ripening culture. ST and LH have a key role in curd acidification and proteolysis at the beginning of the manufacture but are considered to be lyzed for a great part of them at the ripening step. The aim of this work was to assess the metabolic activity of these bacteria throughout manufacture and ripening. During Emmental cheesemaking, LH and ST were subjected to i) population quantification by numerations and by quantitative PCR (qPCR) ii) reverse transcription (RT) Temporal Temperature Gel Electrophoresis (TTGE) iii) transcript quantification by RT-qPCR targeting 16S rRNA, tuf and groL mRNAs to evaluate bacterial metabolic activity. During ripening, ST and LH numerations showed a 2.5 log 10 loss of culturability whereas qPCR on pelleted cells revealed only one log 10 of decrease for both of these species. 10 9 ST and 10 8 LH cells/g of cheese still remained. They contained a stable number of 16S transcript and at least 10 6 copies of mRNAs per 10 9 cells until the end of ripening. These results prove the unexpected persistency of thermophilic lactic acid bacteria starters (ST and LH) metabolic activity until the end of ripening and open new perspectives in term of their involvement in the quality of cheeses during ripening.

Isolation of RNA and DNA from Biofilm Samples Obtained by Laser Capture Microdissection Microscopy: Figure 1.

INTRODUCTIONThe metabolic activities of bacteria growing in biofilms result in spatial gradients of oxygen, nutrients, and waste products. Because bacteria respond to local environmental conditions through changes in gene expression, mRNA levels of individual genes may vary spatially among bacteria within the biofilm. This article describes an approach to isolate RNA for quantification from cells at localized sites within biofilms. Biofilm thin sections are generated by embedding biofilms in cryoembedding resin, freezing the embedded biofilms on dry ice, and cutting with a cryomicrotome. The sections are placed on membrane-coated microscope slides and maintained on dry ice. Laser capture microdissection microscopy (LCMM) is used to dissect small subsets of cells at different regions within the biofilms, and RNA is extracted from the samples using either hot phenol or TRI reagent. A TRI reagent-based DNA extraction method is also presented.

Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater

This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used to calculate bacterial growth efficiency (BGE). Bacterial degradation of DOC increased with increasing exposure to simulated sunlight and availability of phosphorus and no detectable growth occurred on DOC that was not pre-exposed to simulated sunlight. The outcome of photochemical degradation of DOC changed with increasing availability of phosphorus, resulting in an increase in BGE from about 5% to 30%. Thus, the availability of phosphorus has major implications for the quantitative transfer of carbon in microbial food webs.

Pitting initiation of 316L stainless steel in the media of sulfate-reducing and iron-oxidizing bacteria

Pitting corrosion behavior of stainless steel 316L in the presence of aerobic and anaerobic bacteria isolated from cooling water system in oil refinery was investigated using open circuit potential measurement, electrochemically impedance spectroscopy, scanning electron microscopy examinations, and energy dispersive spectrum analysis. The results show the corrosion potential (Ecor) and polarization resistance (Rp) decrease in the presence of sulfate-reducing bacteria (SRB), iron-oxidizing bacteria (IOB), and a combination of SRB and IOB, in comparison with those observed in the sterile medium for the same exposure time. The presence of SRB demonstrated higher corrosion rates than IOB. The combination of SRB and IOB created the highest corrosion rate. The metabolic activity of bacteria and the integrality and compactness of biofilm influenced the pitting corrosion process, increased the corrosion damage degree of the passive film, and accelerated the pitting corrosion. It is suggested that SRB and IOB in influencing the pitting corrosion of 316L SS is highlighted.

Seasonal changes in the concentration and metabolic activity of bacteria and viruses at an Antarctic coastal site

Bacteria play a key role in the world's oceans, supporting nutrient remineralisation and mediating carbon transfer. Little is known about annual changes in bacterial concentration, produc- tion and metabolism during the extreme seasonal changes in biological productivity in Antarctic waters. We measured rates of bacterial production, concentrations of viruses and bacteria and envi- ronmental parameters between February 2004 and January 2005 at an Antarctic coastal site. Concen- trations of total bacteria and viruses were obtained using 4',6-diamidino-2-phenylindole (DAPI) and SYBR Green I (Molecular Probes), respectively. Populations of bacteria in different metabolic states were estimated using vital stains. Concentrations of bacteria with intact or compromised plasma membranes were estimated using BacLight (Molecular Probes) and active cells estimated using 6- carboxyfluorescein diacetate (6CFDA). Our study showed 6CFDA and BacLight gave rapid and eco- logically valuable insights into bacterial physiology, production and growth in natural Antarctic com- munities that were poorly represented by changes in total cell concentrations. Concentrations of total, active and intact bacteria declined rapidly at the end of summer probably owing to viral infection and microheterotrophic grazing. The decline continued over winter, likely owing to substrate limitation, and concentrations only increased after the phytoplankton bloom in spring and summer. Bacterial abundance was positively correlated with particulate organic carbon (POC) and nitrogen (PON), but not dissolved organic carbon (DOC), reflecting the refractory nature of the DOC pool. Only active and intact bacteria were significantly correlated with concentrations of chl a and rates of bacterial production. Furthermore, the obtained rates of ( 3 H)thymidine uptake suggest that bacterial growth rates can be sustained by the populations identified as intact or by active cells alone.

Localized corrosion behavior of 316L stainless steel in the presence of sulfate-reducing and iron-oxidizing bacteria

Localized corrosion behavior of 316L stainless steel was investigated in the presence of sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB) isolated from cooling water system using polarization measurement, scanning electron microscopy (SEM) examinations and energy dispersive spectrum (EDS) analysis. The results show the corrosion potential ( E corr) and breakdown potential ( E b) of SS decreased in turn with the presence of IOB, SRB and SRB + IOB, indicating decreased relative resistance to localized corrosion. E corr in the sterile medium remained virtually unchanged with exposure time, indicating that localized attack did not occur. However, micrometer-scale pitting was observed on the SS surface in the presence of bacteria. The presence of SRB demonstrated higher corrosion rates than IOB. The combination of SRB and IOB yielded the highest corrosion rate. The presence and metabolic activities of bacteria on SS surface produce environments that can alter rates of partial reactions in corrosion processes and shift corrosion mechanisms. The most severe microbiologically induced corrosion takes place in aquatic solution where physiological groups of aerobic and anaerobic microorganisms interact.

Virus and bacteria dynamics of a coastal sediment: Implication for benthic carbon cycling

We measured microbial heterotrophic activity, bacteria, and virus‐like particle (VLP) abundance in homogenized, undiluted, and anoxic enclosures of sediment collected at a coastal station. The bacterial growth rate and VLP net production increased along with the respiratory activity in response to temperature. This suggests that VLPs represent a dynamic component of benthic microbial communities and that the net production of viriobenthos is regulated by the metabolic activity of bacteria. The abundance, net production, and decay rate of VLPs were significantly higher than those encountered in most pelagic systems. However, the rates were lower than the very few available potential rates (three studies) of viriobenthic activity, which all were obtained applying different slurry approaches. Our measurements support the general observation that virus abundance and production correlate with the trophic status of the environment and show that microbial activity can regulate the viriobenthic production in undiluted, homogenized marine sediments. The virus‐induced bacterial mortality corresponded to ~20% of bacterial net production and ~2% h−1 of the total bacterial population. This is moderate compared with the results of most pelagic studies, and the associated leakage of lysates (dissolved organic carbon) only amounted to 4‐8% of the produced dissolved inorganic carbon. Despite high standing stocks and relatively high turnover rates, VLP‐induced bacterial lysis represented only a minor shunt in the benthic carbon cycle at the investigated site.

Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature

We had previously shown that the psychrotrophic bacterium Pseudomonas fluorescens can act as a pathogen, inducing apoptosis and necrosis in neurons and glial cells. In the present study, we investigated the influence of the growth temperature of P. fluorescens on its infectious potential. Adherence of P. fluorescens to glial cells was found to be maximal with bacteria grown at a low temperature (8 °C). At that temperature the swimming behaviour was markedly reduced. An increase in the growth temperature to 19, 28 or 32 °C strongly diminished the binding of bacteria to host cells. Thus, the adhesion phenotype of P. fluorescens appears to be independent of the motility of the bacteria. The apoptotic effect of P. fluorescens, determined by morphological (nuclear condensation) and biochemical (induction of nitric oxide synthase activity) indicators, correlated well with its binding activity on glial cells. In contrast, there was a clear dissociation between maximum binding and maximal necrotic action (measured by the release of lactate dehydrogenase) observed with bacteria grown at 19 °C. As suggested by capillary electrophoresis analysis, the differences in apoptotic effects may be related to variations in the molecular structure of LPS originating from bacteria grown at low and high temperatures, whereas the necrotic effect, which was maximal at the optimum temperature for the secretion of exoenzymes, could reflect variations in the metabolic activity of bacteria.

Microbial Induced Corrosion (MIC) on DHP Copper by Desulfovibrio Desulfuricans and Bacillus Megaterium Strains in Media Simulating Heater Waters

The complexity and diversity of microbial populations in water heating systems of steam generators make it necessary to study the magnitude of the metabolic activity of bacteria and biofilm development that may lead to degradation of metal components through microbial induced corrosion (MIC).Electrolytes simulating the conditions found in heater water networks were used to induce biofilm formation on DHP copper coupons by Desulfovibrio desulfuricans DSMZ and Bacillus megaterium C10, a commercial strain and an isolate from these waters, respectively. In order to enhance their action, industrial waters enriched with the minimum nutrient content such as sodium lactate and sodium sulphite for the DSMZ strain and glucose, proteose peptone and starch for the C10 strain were employed.Biofilm formation was studied under controlled temperature, time, shaking, pH and concentrations of the media used in this study. Then, the samples were electrochemically tested in an artificial solution of sea water as control medium, based on the hypothesis that the action of an aggressive biofilm/electrolyte medium generates damaged and non-damaged areas on the metal surface, and assuming that the sea water trial can detect the latter. Hence, a higher anodic current was associated with a lower degradation of the metal surface by the action of one of the media under study.All these trials were performed along with bacterial count, scanning electron microscopy (SEM) and atomic absorption spectroscopy (AAS).Furthermore, it was possible to identify under which conditions MIC on DHP copper occurred and complex mechanisms from retention of cations to diffusion processes at the biofilm/tested media interface level were proposed. Surface corrosion by MIC took place on DHP copper; therefore, greater control on the treatment of industrial waters is highly desirable.

Correlation in inorganic ion concentration between saliva and plaque fluid.

The composition and the concentration of inorganic ions in dental plaque significantly influence the initiation and the development of dental caries through altering the degree of saturation of the aqueous phase surrounding the dental enamel. In order to know how plaque is affected by saliva, the composition and the concentration of inorganic ions in saliva and plaque fluid were investigated. The ionic concentrations of sodium and chlorine had similar values between plaque fluid and saliva. However, the concentrations of the inorganic ions such as ammonium, potassium, magnesium, calcium, and phosphate were significantly different between plaque fluid and saliva. This meant that the saliva and plaque fluid were different in its inorganic composition presumably reflected by the metabolic activity of bacteria in the plaque. On the other hand, as for the correlation coefficients between plaque fluid and saliva composition, statistically significant correlation was observed in ions such as sodium, ammonium, potassium, magnesium, and chlorine but not in calcium, phosphate, or in pH values. This was possibly due to the fact that saliva was the main source of supply of these ions. However as for calcium and phosphate, no close correlation was found possibly because they could be supplied also through tooth enamel dissolution. The discrepancy of the results with former studies on this point was speculatively explained by,the difference of the plaque age used. It was considered reasonable that the pH value was independent, as it is mainly decided by the activity of the bacteria in the plaque.