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PubMed2006

Iron and arsenic release from aquifer solids in response to biostimulation.

Biostimulation has been used at various contaminated sites to promote the reductive dechlorination of trichloroethylene (TCE), but the addition of carbon and energy donor also stimulates bacteria that use Fe(III) as the terminal electron acceptor (TEA) in potential competition with dechlorination processes. Microcosm studies were conducted to determine the influence of various carbon donors on the extent of reductive dissolution of aquifer solids containing Fe(III) and arsenic. Glucose, a fermentable and respirable carbon donor, led to the production of 1500 mg Fe(II) kg(-1), or 24% of the total Fe in the aquifer sediment being reduced to Fe(II), whereas the same concentration of carbon as acetate resulted in only 300 mg Fe(II) kg(-1) being produced. The biogenic Fe(II) produced with acetate was exclusively associated with the solid phase whereas with fermentable carbon donors as whey and glucose, 22 and 54% of the Fe(II) was in solution. With fermentation, some of the metabolites appear to be electron shuttling chemicals and chelating agents that facilitate the reductive dissolution of even crystalline Fe(III) oxides. Without the presence of electron shuttling chemicals, only surficial Fe in direct contact with the bacteria was bioavailable, as illustrated when acetate was used. Regardless of carbon donor type and concentration, As concentrations in the water exceeded drinking water standards. The As dissolution appears to have been the result of the direct use of As as an electron acceptor by dissimilatory arsenic reducing bacteria. Our findings indicate that selection of the carbon and energy donor for biostimulation for remediation of chlorinated solvent impacted aquifers may greatly influence the extent of the reductive dissolution of iron minerals in direct competition with dechlorination processes. Biostimulation may also result in a significant release of As to the solution phase, contributing to further contamination of the aquifer.

Acetates↗
PubMed1998

In vitro experimental research of rabbit condrocytes biostimulation with diode laser Ga-Al-As: a preliminary study.

The scope of our study was to verify the effects of a new diode laser device with active material composed of Gallium, Aluminum and Arsenic (Ga-Al-As) configured as MOCVD (780 nm., 3000 mW) for the biostimulation of the cartilage cells in vitro. The condrocytes cells, withdrawn from the cartilage of the medial condyle of the femur of the rabbit, were cultivated, incubated and subject to biostimulation treatment with the laser. The condrocytes cells were placed in 24 Petri dishes at the concentration of 0.25 x 10(5)/ml and divided into 4 groups: 3 group (I, II, III) were treated with the laser and the fourth group (IV) was used as the control group. At the end of the treatment, all four groups, were evaluated with a MTT test and a cell count of the condrocytes cells. Group III (300 J, 1 Watt, 300 Hz, 10' of exposure time with a pulsating emission) provided the best results in terms of cell viability (MTT test) and for the number of cells found in the dishes when compared to the other treated groups and the control group. The results obtained with the use of this new diode laser Ga-Al-As device in the biostimulation of the cartilage tissue, permits us to consider the use of this device clinically.

Aluminum↗
PubMed2001

[Laser's biostimulation in healing or crural ulcerations].

The objective of this paper was to evaluate effect of laser's biostimulation on the process of healing of crural ulcerations. Three comparative groups of patients, A, B and C, were made at random from the patients with venous crural ulcerations. The group A consisted of 17, the group B 15, the group C 17 patients. The patients in all comparative groups were treated pharmacologically and got compress therapy. Ulcerations at patients in group A were additionally irradiated by light of biostimulation's laser (810 nm) in this way that every time ulcerations got dose of energy 4 J/cm2. The patient's in-group B additionally got blind trial (with placebo in the form of quasi-laserotherapy). The evaluated factors were to estimate how laser's biostimulation causes any changes of the size of the ulcers and of the volume of tissue defect. The speed of changes of size and volume of tissue defect per week was calculated. After the treatment there was statistically significant decrease of size of ulcers in all comparative groups while there was no statistically significant difference between the groups observed. After the treatment there was statistically significant decrease of volume of ulcers only in groups A and C but there was no statistically significant difference between the groups observed.

Adult↗
PubMed1983

[Effect of a biostimulant formed by yeastlike fungi on the dynamics of the accumulation of CoA, biotin and levorin in the process of growth of S. levoris].

Regularities of the effect of a biostimulator produced by years-like fungi on accumulation of CoA, biotin and levorin in a developing culture of S. levoris were studied. It was shown that addition of the biostimulator to the fermentation medium resulted in increased accumulation of CoA and biotin in the mycelium of the levorin-producing culture within the first 48 hours of the growth and in their more intensive consumption at the final stages of the fermentation process. The rate of the levorin synthesis in the medium with the biostimulator markedly exceeded that in the control.

Antifungal Agents↗
PubMed1981

[Isolation and properties of a biostimulator formed by yeast-like fungi and its effect on levorin biosynthesis].

Experiments on isolation of active substances or biostimulators from the culture fluids of yeast-like fungi of Candida (C. tropicalis, strain 159) were performed. Addition of the biostimulators to the fermentation medium for cultivation of the levorin-producing actinomycete provided the same levels of the antibiotic synthesis as mixed cultivation of the actinomycete and C. tropicalis. The biostimulators were found to be thermostable and stable within a wide pH range (2.0--14.0). They are low-molecular compounds of the organic nature.

Antifungal Agents↗
PubMed2002

Biostimulation and bioaugmentation for on-site treatment of weathered diesel fuel in Arctic soil.

Bioremediation of weathered diesel fuel in Arctic soil at low temperature was studied both on-site in small-scale biopiles and in laboratory microcosms. The field study site was on Ellesmere Island (82 degrees 30'N, 62 degrees 20'W). Biostimulation was by fertilization with phosphorous and nitrogen. Bioaugmentation was with an enrichment culture originating from the field site. In biopiles, total petroleum hydrocarbons (TPH) were reduced from 2.9 to 0.5 mg/g of dry soil over a period of 65 days. In microcosms at 7 degrees C, TPH were reduced from 2.4 to 0.5 mg/g of dry soil over a period of 90 days. Inoculation had no effect on hydrocarbon removal in biopiles or in microcosms. Maximum TPH removal rates in the biopiles were approximately 90 micro g of TPH g(-1) of soil day(-1), occurring during the first 14 days when ambient temperature ranged from 0 to 10 degrees C. The fate of three phylotypes present in the inoculum was monitored using most-probable-number PCR, targeting 16S rRNA genes. Populations of all three phylotypes increased more than 100-fold during incubation of both uninoculated and inoculated biopiles. The inoculum increased the initial populations of the phylotypes but did not significantly affect their final populations. Thus, biostimulation on site enriched populations that were also selected in laboratory enrichment cultures.

Arctic Regions↗
PubMed2006

Heterogeneous response to biostimulation for U(VI) reduction in replicated sediment microcosms.

A field-scale experiment to assess biostimulation of uranium reduction is underway at the Natural and Accelerated Bioremediation Research Field Research Center (FRC) in Oak Ridge, Tennessee. To simulate the field experiment, we established replicate batch microcosms containing well-mixed contaminated sediment from a well within the FRC treatment zone, and we added an inoculum from a pilot-scale fluidized bed reactor representing the inoculum in the field experiment. After reduction of nitrate, both sulfate and soluble U(VI) concentration decreased. X-ray absorption near edge structure (XANES) spectroscopy confirmed formation of U(IV) in sediment from biostimulated microcosms, but did not detect reduction of solid-phase Fe(III). Two to three fragments dominated terminal restriction fragment length polymorphism (T-RFLP) profiles of the 16S rDNA gene. Comparison to a clone library indicated these fragments represented denitrifying organisms related to Acidovorax, and Acidovorax isolates from the inoculum were subsequently shown to reduce U(VI). Investigation using the T-RFLP Analysis Program (TAP T-RFLP) and chemical analyses detected the presence and activity of fermenting and sulfate-reducing bacteria after 2 weeks. These organisms likely contributed to uranium reduction. In some microcosms, soluble U(VI) concentration leveled off or rebounded, indicating microbial and/or mineralogical heterogeneity among samples. Sulfate, acetate, and ethanol were depleted only in those microcosms exhibiting a rebound in soluble U(VI). This suggests that rates of U(VI) desorption can exceed rates of U(VI) reduction when sulfate-reducing bacteria become substrate-limited. These observations underscore the importance of effective chemical delivery and the role of serial and parallel processes in uranium reduction.

Bacteria↗
PubMed2005

Response of 1,2-dichloroethane-adapted microbial communities to ex-situ biostimulation of polluted groundwater.

The microbial community of a groundwater system contaminated by 1,2-dichloroethane (1,2-DCA), a toxic and persistent chlorinated hydrocarbon, has been investigated for its response to biostimulation finalized to 1,2-DCA removal by reductive dehalogenation. The microbial population profile of samples from different wells in the aquifer and from microcosms enriched in the laboratory with different organic electron donors was analyzed by ARISA (Amplified Ribosomal Intergenic Spacer Analysis) and DGGE (Denaturing Gradient Gel Electrophoresis) of 16S rRNA genes. 1,2-DCA was completely removed with release of ethene from most of the microcosms supplemented with lactate, acetate plus formate, while cheese whey supported 1,2-DCA dehalogenation only after a lag period. Microbial species richness deduced from ARISA profiles of the microbial community before and after electron donor amendments indicated that the response of the community to biostimulation was heterogeneous and depended on the well from which groundwater was sampled. Sequencing of 16S rRNA genes separated by DGGE indicated the presence of bacteria previously associated with soils and groundwater polluted by halogenated hydrocarbons or present in consortia active in the removal of these compounds. A PCR assay specific for Desulfitobacterium sp. showed the enrichment of this genus in some of the microcosms. The dehalogenation potential of the microbial community was confirmed by the amplification of dehalogenase-related sequences from the most active microcosms. Cloning and sequencing of PCR products indicated the presence in the metagenome of the bacterial community of a new dehalogenase potentially involved in 1,2-DCA reductive dechlorination.

Amino Acid Sequence↗
PubMed2004

Comparative bioremediation of soils contaminated with diesel oil by natural attenuation, biostimulation and bioaugmentation.

Bioremediation of diesel oil in soil can occur by natural attenuation, or treated by biostimulation or bioaugmentation. In this study we evaluated all three technologies on the degradation of total petroleum hydrocarbons (TPH) in soil. In addition, the number of diesel-degrading microorganisms present and microbial activity as indexed by the dehydrogenase assay were monitored. Soils contaminated with diesel oil in the field were collected from Long Beach, California, USA and Hong Kong, China. After 12 weeks of incubation, all three treatments showed differing effects on the degradation of light (C12-C23) and heavy (C23-C40) fractions of TPH in the soil samples. Bioaugmentation of the Long Beach soil showed the greatest degradation in the light (72.7%) and heavy (75.2%) fractions of TPH. Natural attenuation was more effective than biostimulation (addition of nutrients), most notably in the Hong Kong soil. The greatest microbial activity (dehydrogenase activity) was observed with bioaugmentation of the Long Beach soil (3.3-fold) and upon natural attenuation of the Hong Kong sample (4.0-fold). The number of diesel-degrading microorganisms and heterotrophic population was not influenced by the bioremediation treatments. Soil properties and the indigenous soil microbial population affect the degree of biodegradation; hence detailed site specific characterization studies are needed prior to deciding on the proper bioremediation method.

Biodegradation, Environmental↗
PubMed2005

Natural attenuation, biostimulation and bioaugmentation on biodegradation of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediments.

The biodegradability of a mixture of PAHs, namely fluorene (Fl), phenanthrene (Phe) and pyrene (Pyr), in mangrove sediment slurry was investigated. At the end of week 4, natural attenuation based on the presence of autochthonous microorganisms degraded more than 99% Fl and Phe but only around 30% of Pyr were degraded. Biostimulation with addition of mineral salt medium degraded over 97% of all three PAHs, showing that nutrient amendment could enhance Pyr degradation. Bioaugmentation with inoculation of a PAH-degrading bacterial consortium enriched from mangrove sediments did not show any promotion effect and the degradation percentages of three PAHs were similar to that by natural attenuation. Some inhibitory effect was observed in bioaugmentation treatment in week 1 with only 50% Fl and 70% Phe degraded. These results indicate that autochthonous microbes may interact and even compete with the enriched consortium during PAH biodegradation. Natural attenuation appeared to be the most appropriate way to remedy Fl- and Phe-contaminated mangrove sediments while biostimulation was more capable to degrade Pyr-contaminated sediments. The study also shows that although a large portion of the added PAHs (more than 95%) was adsorbed onto the sediments at the beginning of the experiment, most PAHs were degraded in 4 weeks, suggesting that the degraders could utilize the adsorbed PAHs efficiently.

Analysis of Variance↗
PubMed2005

Effect of biostimulation on the expression of estrus in postpartum Angus cows.

The objective of this study was to evaluate the effect of biostimulation by bull exposure on the expression of estrus in postpartum Angus cows. Ninety Angus cows and their calves were allocated by parity and body frame to three pens (30/pen). From 1-week post partum, one epididectomized mature Angus bull was placed with Groups A and B (BE), whereas Group C served as a Control (NE). Data for duration of estrus (DE), total mounts received (TMR), and intensity of estrus (IE) were recorded using HeatWatch. At either the first or second postpartum estrus, there were no differences between BE and NE cows for DE, TMR and IE. However, the period after onset of estrus, cow within treatment and the interaction treatment by period exerted a significant influence on IE. Overall, the greatest IE (P<0.0001) was observed during the first two periods (6h). At the first postpartum estrus, IE tended (P<0.11) to be greater in BE than NE cows during the first 3h after onset of estrus. However, IE was greater (P<0.02) in NE cows than BE cows during 4-6h after onset of estrus. At the second postpartum estrus, IE did not differ between BE and NE cows during the first 3h after onset of estrus. However, from 4 to 9h after onset of estrus, IE was greater (P<006) in NE cows than BE cows. From the results of this study, it was concluded that DE, TMR and IE were not influenced by biostimulation. However, the manner in which mounting activities were distributed across the duration of estrus was influenced by the presence of bulls.

Animals↗
PubMed2000

Influence of bull biostimulation, season and parity on resumption of ovarian activity of zebu (Bos indicus) cattle following parturition.

A total of 135 postpartum suckled zebu cows were assigned randomly at calving to two treatments: cows exposed to vasectomised bulls (Mature Bull Exposure, MBE) and cows not exposed to bulls (No Bull Exposure, NBE) for a period of 150 days postpartum. This study was conducted to determine the influence of bull biostimulation, season and parity on postpartum reproductive performance of Bos indicus cattle. The trials were conducted in two seasons: cows calving in the dry season and cows calving in the rainy season. Cows with an increase in serum progesterone (P(4)) concentration of >1 ng/ml from the weekly blood samples were used to analyse the number of days from calving to the time of resumption of ovarian activity. The introduction of vasectomised bulls shortened the postpartum anoestrus in cattle following calving. Mean interval from calving to resumption of ovarian activity for the MBE cows was 71.7 days, which was significantly earlier following calving than the NBE cows with a duration of 77.8 days. By 60 to 80 days postpartum, the proportion of cows at resumption of postpartum activity for MBE cows was greater than for the NBE cows. Mean interval from calving to resumption of ovarian activity for cows that calved in the dry season was 71.3 days, which was significantly earlier than for cows that calved in the rainy season (78.6 days). At 60 days postpartum, the proportion of cows at resumption of postpartum ovarin activity for cows that calved in the dry season was greater than the cows that calved in the rainy season. Mean interval from parturition to resumption of ovarian activity for cows with three to five calvings was 65.1 days, which was significantly earlier than the value of 71. 2 days for cows with one to two calvings. By 60 to 80 days postpartum, the proportion of cows at onset of ovarian activity for cows with three to five calvings was greater than those cows with one to two calvings. Cows that calved in the dry season completed uterine involution by 24.4 days, which was significantly shorter than the duration of 26.5 days for cows that calved in the rainy season. Cows with three to five calvings completed uterine involution earlier than those with one to two calvings. It is concluded that bull-cow biostimulation influences reproductive activity in the cow possibly through olfactory cues (pheromones).

Animals↗
PubMedDate not supplied

Phenol degradation and toxicity assessment upon biostimulation to an indigenous Rhizobium Ralstonia taiwanensis.

This study provides a first attempt from a toxicological perspective to put forward, in general terms and explanations, combined toxic interactions and biostimulation strategy upon nutrient medium to Ralstonia taiwanensis for bioremediation. Dose-response analysis clearly revealed that most of the supplemented nutrients tested (except for gluconic acid) synergistically interact with chronic toxicity to phenol, especially at low doses. Acute toxicity based upon adaptation lag is a more appropriate indicator for comparative analysis of toxicity due to similar toxic ranking at almost all effective concentrations. In addition, comparison upon acute and chronic toxicity for various nutrient media also suggests in parallel that acute toxicity is more significant than chronic toxicity possibly as the result of a more sensitive response of adaptation lag to growth in different media. Feasibility of adding extra nutrient substrates (e.g., phenol, gluconic acid, yeast extract, pyruvic acid, acetic acid, and glycerol) to stimulate proliferation of phenol degraders for better phenol degradation performance was also assessed. The results show that using acetic acid as the augmented nutrient source might be the most feasible biostimulation strategy for phenol degradation.

Biodegradation, Environmental↗
PubMed2000

Biostimulation of bone marrow cells with a diode soft laser.

In recent years, the use of low-intensity red light in regeneration of soft tissue has been increasingly pursued. As far as hard tissue is concerned, the biostimulating effect of laser has already been demonstrated successfully in more rapid healing of tibial bone fractures in mice at a dosage of 2.4 J. However, the effect of light of a low dose laser directly on osteoblasts has not been investigated yet. The aim of this study was to determine the effect of continuous wave diode laser irradiation on osteoblasts derived mesenchymal cells. Three groups of 10 cultures each were irradiated 3 times (days 3, 5, 7) with a pulsed diode soft laser with a wavelength of 690 nm for 60 s. Another 3 groups of 10 cultures each were used as control groups. A newly developed method employing the fluorescent antibiotic tetracycline was used to compare bone growth on these culture substrates after a period of 8, 12 and 16 days, respectively. It was found that all lased cultures demonstrated significantly more fluorescent bone deposits than the non-lased cultures. The difference was significant, as tested by the Tukey Test (P < 0.0001) in the cultures examined after 16 days. Hence it is concluded that irradiation with a pulsed diode soft laser has a biostimulating effect on osteoblasts in vitro, which might be used in osseointegration of dental implants.

Animals↗
PubMed2001

Succession of microbial communities during a biostimulation process as evaluated by DGGE and clone library analyses.

AIMS: The objective of this study was to investigate the changes in the indigenous bacterial community structure for assessing the impact of biostimulation on spilled oil. METHODS AND RESULTS: Changes in the bacterial community structure were monitored by denaturing gradient gel electrophoresis (DGGE) and clone library methods based on 16S rRNA gene (rDNA) sequences. The results of DGGE, coupled with the use of the Shannon index and principal component analysis (PCA) and clone library analyses, were consistent. In the treated (fertilized) area, one operational taxonomic unit (OTU) became dominant during the fertilization period, and it was most closely related to Pseudomonas putida. CONCLUSIONS: The bacterial community structure in the treated area was markedly different from that in the control (non-fertilized) area during the fertilization period, but in the two areas it became similar at 14 weeks after the end of fertilization. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that the bacterial community structure was disrupted by the biostimulation treatment, but that it recovered immediately after the end of fertilization.

Bacteria↗
PubMed2000

Monitoring impact of in situ biostimulation treatment on groundwater bacterial community by DGGE.

Changes in bacterial diversity during the field experiment on biostimulation were monitored by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA fragments. The results revealed that the bacterial community was disturbed after the start of treatment, continued to change for 45 days or 60 days and then formed a relatively stable community different from the original community structure. DGGE analysis of soluble methane monooxygenase (sMMO) hydroxylase gene fragments, mmoX, was performed to monitor the shifts in the numerically dominant sMMO-containing methanotrophs during the field experiment. Sequence analysis on the mmoX gene fragments from the DGGE bands implied that the biostimulation treatment caused a shift of potential dominant sMMO-containing methanotrophs from type I methanotrophs to type II methanotrophs.

Journal Article↗
PubMed2001

Bioremediation (natural attenuation and biostimulation) of diesel-oil-contaminated soil in an alpine glacier skiing area.

We investigated the feasibility of bioremediation as a treatment option for a chronically diesel-oil-polluted soil in an alpine glacier area at an altitude of 2,875 m above sea level. To examine the efficiencies of natural attenuation and biostimulation, we used field-incubated lysimeters (mesocosms) with unfertilized and fertilized (N-P-K) soil. For three summer seasons (July 1997 to September 1999), we monitored changes in hydrocarbon concentrations in soil and soil leachate and the accompanying changes in soil microbial counts and activity. A significant reduction in the diesel oil level could be achieved. At the end of the third summer season (after 780 days), the initial level of contamination (2,612 +/- 70 microg of hydrocarbons g [dry weight] of soil(-1)) was reduced by (50 +/- 4)% and (70 +/- 2)% in the unfertilized and fertilized soil, respectively. Nonetheless, the residual levels of contamination (1,296 +/- 110 and 774 +/- 52 microg of hydrocarbons g [dry weight] of soil(-1) in the unfertilized and fertilized soil, respectively) were still high. Most of the hydrocarbon loss occurred during the first summer season ([42 +/- 6]% loss) in the fertilized soil and during the second summer season ([41 +/- 4]% loss) in the unfertilized soil. In the fertilized soil, all biological parameters (microbial numbers, soil respiration, catalase and lipase activities) were significantly enhanced and correlated significantly with each other, as well as with the residual hydrocarbon concentration, pointing to the importance of biodegradation. The effect of biostimulation of the indigenous soil microorganisms declined with time. The microbial activities in the unfertilized soil fluctuated around background levels during the whole study.

Austria↗