Effect Of Food Concentration Research Articles

Laboratory Study On Activating Indigenous Microorganisms to Enhance Oil Recovery

Abstract A heavy crude oil (19 ° API gravity) and connate water (from the Mauddud formation in El-Bahrain) were used in the present study, to investigate the effect of microbial growth on water viscosity, pH and oil/water interfacial tension. Displacement tests were carried out to study the effect of nutrient concentration, incubation temperature and carbonate content on the oil recovery from waterflooded residual oil. The study showed that the indigenous bacterial population in the formation water and the crude oil could be activated by a molasses based nutrient to produce biosurfactants, acids, polymers, and gases. It was found that a nutrient slug of 4% by weight molasses concentration was the optimum at which the indigenous microorganisms have been given maximum growth and resulted in higher oil recovery than that obtained at other tested molasses concentrations. For the tested incubation temperatures, the results showed that the indigenous microbial growth was better at 25 ° C which in turn was reflected positively upon oil recovery. It was also found that the presence of carbonates in a reservoir can provide a buffering capacity for complete fermentation to occur where it neutralizes the acids produced by bacteria and increases the carbon dioxide production. The oil recovery was increased by increasing the carbonate content. However, with further increase in carbonate content above 20% no more oil was recovered. Introduction Microbial methods for increasing oil recovery are potentially cost-effective even at relatively low crude oil prices. Microbial formulations can be applied in a variety of methods including permeability modification treatments and microbial-enhanced waterflooding. A number of mechanisms have been considered to be important for the recovery of residual oil through the application of microbial enhanced oil recovery (MEOR). Such mechanisms include: production of biosurfactants to reduce the oil/water interfacial tension and improve the displacement efficiency, production of biopolymers to improve mobility control and increase sweep efficiency, production of solvents that reduce the oil viscosity and increase its mobility, and production of biogenic acids that dissolve carbonate rock, increase pore space and produce more carbon dioxide. Carbon dioxide in the gaseous form would expand producing a driving mechanism, or if dissolved would reduce the crude viscosity thus increasing its mobility(1–5). The in situ application of the process used to accomplish these mechanisms requires the growth and/or metabolism of microorganisms in the rock matrix. Whether the microorganisms used to carry out these functions are indigenous or added exogenously, they must function effectively at reservoir conditions of salinity and temperature with the aid of suitable nutrients. The existence of indigenous bacteria in many oil reservoirs was practically proved. These indigenous microorganisms nearly always belong to undescribed species, or even to new genera(6). In nearly all the cases studied up to now, the indigenous bacteria consist solely of strict anaerobes. The species developing in the oil reservoirs seem to have undergone a natural selection in situ as a function of their physiological properties. They may also be related to the geological period during which they were put into place.

Zebra mussel filter feeding and food-limited production of Daphnia: recent changes in lower trophic level dynamics of Oneida Lake, New York, U.S.A.

Exotic zebra mussels can alter lower trophic level dynamics in lakes that they colonize by consuming large quantities of phytoplankton. We simulated the indirect effects of zebra mussel grazing on Daphnia by artificially reducing phytoplankton concentration for in situ Daphnia reproduction experiments. The response of Daphnia reproduction to reduced phytoplankton was evaluated for both the in situ experiments and field observations in Oneida Lake, New York, U.S.A. Oneida Lake has had an abundant population of zebra mussels since 1992. Our experiments revealed that fecundity of individuals from two species of Daphnia was positively related to phytoplankton concentration during the spring clearwater phase, although there was no discernible effect of food concentration on fecundity in summer cyanobacteria-dominated assemblages. The experimental results suggest that Daphnia fecundity responds to chlorophyll a concentrations < 2 μg l-1. The years since zebra mussels became abundant in Oneida Lake have been characterized by high water clarity, low chlorophyll concentrations, long clearwater phases, and low Daphnia biomass compared with the previous 17 years. The food web effects of zebra mussel grazing are complex and it will take more years for impacts at higher trophic levels to develop and be identified.

Colony patterning of Aspergillus oryzae on agar media

To clarity the effects of nutrient concentration and diffusion on the pattern formation of fungal colonies, the colony patterning ofAspergillus oryzae at various nutrient and agar levels was studied experimentally and was summarized in a colony morphology diagram. Roles of the nutrient content and the relaxation of nutrient distribution on the colony patterning were discussed based on a computer model of the mycelial growth. The colony morphology changed from compact to ramified as the nutrient and agar levels were lowered. No clear boundary was found between these two morphologies. The deterioration of substrate around the growing colony was detected when the morphic switching from homogeneous into splitting patterns emerged in the growth of ramified colonies. In the mycelial growth model, dense compact colonies developed at low growth rates and high nutrient influx into the colonized area. Under low nutrient levels, splitting colonies appeared at high growth rates as compared with the nutrient influx.

Effects of food availability, larval source and culture method on larval development of Balanus amphitrite amphitrite Darwin: implications for experimental design

Effects of food concentration on larval development of Balanus amphitrite amphitrite Darwin (Crustacea: Cirripedia) were studied in three experiments designed to examine plasticity of survival, time of development and size: I, larvae from a single brood, cultured individually; II, larvae from multiple broods, cultured individually; III, larvae from multiple broods, cultured in groups (batch cultures). Nauplii were fed the diatom Skeletonema costatum (Grev.) Cleve at six concentrations ranging from 0 to 10 6 cells · ml −1 at 24 °C and 30%. salinity. Food concentration had a clear impact on larval survival and development time for B. a. amphitrite and larvae showed the same trends in survival, duration of development, and growth whether they were obtained from single or multiple parents and whether they were cultured individually or in batches. Nauplii of B. a. amphitrite failed to reach the cypris stage at algal concentrations ≤ 10 3 cells · ml −1. Development stopped at nauplius II when larvae were reared at 0–10 2 cells · ml −1 and stopped at nauplius III when larvae were reared at 10 3 cells · ml −1. Survival at 10 5 and 10 6 cells · ml −1 was higher than at 10 4 cells · ml −1. Larvae reared at the three highest food concentrations developed to the cypris stage. Development time from nauplius II to cyprid was similar ( p > 0.10) when larvae were maintained at 10 5 or 10 6 cells · ml −1, but was significantly longer when reared at 10 4 cells · ml −1. The sizes of B. a. amphitrite larvae at a particular stage were similar regardless of food concentration, developmental rate, larval source (from single vs. multiple broods) and the method of culture. In future studies that involve B. a. amphitrite larvae, larval source and method of culture can be selected solely on the basis of questions to be addressed.

Egg Production and Viability in Centropages Typicus: A Laboratory Study on the Effect of Food Concentration

The effect of food concentration on the reproductive success of the copepod Centropages typicus (Copepoda: Calanoida) was studied in the laboratory. Three different regimes of food were tested: absence of food, natural food conditions and a food media enriched with an algal culture. The results showed significant differences in egg production rate between regimes of food, but no significant differences in egg viability. A rapid response (24 h) in egg production rate to increment in the quantity of food was noted. Hatching success was not affected by food conditions prevailing during the incubations.

The effect of food concentration on the scope for growth and growth performance of Ruditapes decussatus (L.) seed reared in an open-flow system

Ruditapes decussatus (L.) seed, 1.6 mm in length, was reared in an open-flow system for 28 days at different concentrations of food: 15, 50, 100, 200 and 300 Isochrysis galbana, clone T-ISO, cells μL−1. Rates of ingestion, absorption, and respiration were measured during the experiment and used to calculate the energy balance. Rate of ingestion and absorption efficiency were the primary physiological processes governing seed growth. Ingestion rates increased with food concentration, up to a maximum of 100 cells μL−1. Greater increases in concentration resulted in a decrease in ingestion. Clearance rates were inversely correlated to food concentration. Absorption efficiency, estimated using the Conover method, also decreased with increasing concentrations of food. Respiration rates were independent of food concentration. Potential growth rates were lower than actual growth rates for each of the concentrations tested, although the effect of food concentration on actual and potential growth was equal, with maximum growth occurring at a concentration of 50 cells μL−1. Thus, SFG (‘scope for growth’) is a good qualitative estimator of actual growth, but a poor quantitative estimator.

Larviculture of the fairy shrimp,Streptocephalus proboscideus (Crustacea: Anostraca): effect of food concentration and physical and chemical properties of the culture medium

Larviculture of the fairy shrimp,Streptocephalus proboscideus (Crustacea: Anostraca): effect of food concentration and physical and chemical properties of the culture medium

Observations of the free‐swimming behavior of Acartia tonsa: Effects of food concentration and turbulent water motion

The free‐swimming behavior of the calanoid copepod Acartia tonsa is described as a function of food concentration and quantified turbulence.In still water, Acartia spent most of its time feeding. Time allocated to feeding bouts did not change much as a function of food concentration (from 98% to 81%). Functional response to food was mainly determined by the duration of feeding bouts and the proportion of time spent in them. Lengthy feeding bouts might be involved with the actual capture and ingestion of food, while brief feeding bouts might be involved in the search for an optimum food density and the discrimination of food quality.Turbulence did not affect the amount of time allocated to feeding bouts but induced a significant shift to bouts of shorter duration at low food concentration. Computed encounter rates were 2.5 times higher in the presence of turbulence and indicated that turbulence intensity might have been enough to increase realized food concentrations to levels comparable to satiation at some of the low food concentrations tested.

Effect of food concentration on the chronic toxicity of sodium dodecyl sulphate to Daphnia magna

Food concentration supplied during subchronic and chronic toxicity tests, is one of the most important factors that might influence the response of test organisms to toxicants. The green microalga Scenedesmus incrassatulus was used as food for the cladoceran Daphnia magna, in a chronic toxicity test with the toxicant sodium dodecyl sulphate (SDS). Test concentrations were 0.625, 1.25, and 2.5 mg l-1 of SDS, equivalent to 1/40, 1/20, and 1/10 of the average 48-h LC50 previously determined. Food concentrations were 9.5, 19, and 38 mg l-1 (dry wt.). Survival and reproduction were recorded, and the data were analyzed using a life-table approach. After 55 days, the main findings were as follows: 1. Average clutch size decreased as food concentration increased and there was a negative interaction between the toxicant and the algal concentration. 2. The Net Reproductive Rate (R0) of the controls fed the lowest food concentration was approximately 10 times higher than the controls fed the highest food concentration. 3. R0's for the treatments with SDS fed the lowest food concentration, were 2.5 to 5 times higher than those fed the highest food concentration. 4. Reproduction in controls and treatments with the same SDS concentrations, became similar as food level increased.

FOOD CONCENTRATION AND TEMPERATURE EFFECTS ON LIFE CYCLE CHARACTERISTICS OF TROPICAL CLADOCERA (Daphnia gessneri Herbst, Diaphanosoma sarsi Richard, Moina reticulata (Daday)): I. DEVELOPMENT TIME

The effects of food concentration and temperature on embryonic and postem-bryonic duration of three tropical species, Daphnia gessneri(1.5mm), Diaphanosoma sarsi(1.2mm) and Moina reticulata(0.8mm), were investigated as part of life cycle studies which included growth, body size and reproduction. These are the very first experimental studies undertaken on these species. The long-term growth experiments were performed under controlled laboratory conditions at all combinations of temperature (22"C, 27"C and 32"C) and constant food concentration (0.03, 0.05, 0.10, 0.25, 0.50 and 1.00 mgC/L) of the unicellular green alga Scenedesmus acutus.Animals were examined twice daily throughout their life cycle from the neonate to third adult instar. In all three species, temperature exerted the most powerful influence on embryonic duration but there was also a smaller food effect. In D. gessneri,postembry-onic durations remained more or less the same at food levels 0.25 mgC/L but were influenced by temperature. At food concentrations of 0.1 mgC/L or lower, postembryonic durations became increasingly prolonged, particularly at high temperatures. This threshold concentration is affected by temperature: in D. gessneri,it was 0.1 mgC/L at 22oC and 27oC but higher at 32oC (between 0.25 and 0.50 mgC/L). At the same temperature of 27oC, the food threshold level varied between species: it was higher (0.25 mgC/L) for D. sarsiand lower (0.05 mgC/L) for M. reticulatacompared with D. gessneri(0.1 mgC/L). In both embryonic and postembryonic durations there is a body size effect as the absolute durations were longest in the largest species and shortest in the smallest species In all three species, prolongation of postembryonic duration at combinations of high temperature and lowered food levels was accompanied by increased number of juvenile instars.

Juvenile survival of a planktonic insect: effects of food limitation and predation

SUMMARY An experiment was conducted to investigate potential impacts of food limitation and copepod predation on juvenile survival of Chaoborus purtctipennis. We tested the hypotheses that: (i) juvenile survival of Chaoborus is influenced more by copepod predation than by starvation in a productive environment, and (ii) food limitation and predation interact to affect survival. Effects of food concentration (approximately 800, 1400 and 2300 microzooplankton 1‐−1) and predator density (0, 1 and 2 Mesocydops edax 1‐−1) on Chaoborus development and survival were evaluated using a 3 × 3 factorial design. Jars containing lake water, the appropriate food and predator treatments, and two Chaoborus (&lt;12h old) were rotated on a plankton wheel at 25°C. Survival and developmental stage were monitored daily until all individuals had either died or moulted to instar II. Predation by Mesocydops was the major source of mortality, causing 87.5% of Chaoborus deaths over all treatments. Chaoborus mortality was significantly higher in treatments with Mesocydops (67–100%) than in predator‐free treatment (0–13%). Development time was significantly longer in the low‐density food treatment than in the highest food treatment. No significant interaction between food limitation and predation was detected. These results suggest that predation by copepods may limit recruitment of juvenile Chaoborus in productive lakes.

Mycorrhizal and non-mycorrhizal Douglas fir grown in hydroculture. The effect of nutrient concentration on the formation and functioning of mycorrhiza

A series of experiments using the Douglas fir as the subject of research were performed in hydroculture. Different relative nutrient addition rates were used prior to and after plants had been inoculated with Laccaria bicolor. The effect of the resulting nutrient conditions on mycorrhiza formation was studied together with the effects on growth and internal nutrient levels. The level of external nutrient concentration influenced mycorrhiza formation and functioning. In general, very low and limiting external nutrient conditions resulted in rapid and good mycorrhiza formation, with the mycorrhiza plants having the same or a lower fresh weight than those of the non-mycorrhizal plants. While under higher nutrient conditions mycorrhiza formation was slower and less abundant, and the mycorrhizal plants had a larger total fresh weight than non-mycorrhizal plants.

Effect of food concentration on body size, egg size, and population dynamics ofBrachionus angularis(Rotatoria)

Effect of food concentration on body size, egg size, and population dynamics of<i>Brachionus angularis</i>(Rotatoria)

Hybridoma growth and monoclonal antibody production in iron-rich protein-free medium: effect of nutrient concentration.

The iron-rich (500 microM ferric citrate) protein-free supplement was added to six different basal media. Cell growth and monoclonal antibody production of a mouse-mouse hybridoma were investigated in 1.3 1 batch cultures performed in a laboratory bioreactor with automatic control of pH and dissolved oxygen concentration. RPMI 1640 served as the control medium. Fortification of the basal medium by balanced mixtures of amino acids and vitamins showed higher positive effect than daily supplementation by glucose and glutamine. Strongly fortified medium, based on RPMI 1640, was found superior to other basal media. The viability index increased by a factor of 3.04 and the total antibody production by a factor of 2.82, relative to the control.

Effect of food concentration on digestion and vacuole passage time in the heterotrichous marine ciliateFibrea salina

Vacuole passage time (VPT) and digestion time (DT) in the heterotrichous marine ciliateFabrea salina (Henneguy) (from cultures) were measured in 1986 under different food concentrations, using epifluorescence microscopy, and employing fluorescent particles andRhodomonas lens as tracers. Both VPT and DT were unaffected by food concentrations ranging form 0 to 106 cells ml−1 and can be treated as constants (120.0 and 71.2 min, respectively). Vacuole life expectancy may be related to the ingestion-rate-determining need forde novo membrane synthesis and “old” vacuole membrane recycling which feeds new endocytotic vacuole production. Both processes are enzyme-controlled, which would explain the observations of other investigators that at least in certain ciliates digestion time is responsive to changes in temperature.

Effect of Food Concentration on the Assimilation and Production Efficiencies of Daphnia galeata G.O. Sars (Crustacea: Cladocera)

Measurements of growth, respiration and ingestion were used to examine the influence of food concentration on the assimilation and individual production efficiencies of Daphnia galeata G. 0. Sars at food concentrations of 2 50, 0.25 and 0-05mg C I1-. A plot of assimilation rate against body size showed an S-shaped curve. In the first adult instar, the rates at 2 50 mg C l-1 were two and five times higher than those at 0 25 and 0.05mg C 1-1, respectively. Assimilation efficiency, gross growth efficiency (K1) and net growth efficiency (K2) showed binomial curves with maxima at the last juvenile or early adult instars. Assimilation efficiency increased with decreasing food concentration; an opposite trend was found for K2. Except for early juvenile instars, K1 was highest at the intermediate food concentration, suggesting that there is an optimal resource concentration for energy transfer efficiency. The lower value of K1 at the higher food concentration was due to lower assimilation efficiency, while that at the lower food concentration was due to high respiration rate relative to the amount of food assimilated. These results demonstrate that food concentration affects the carbon balance not only quantitatively (rates), but also qualitatively (efficiencies). The change in carbon balance with changing food concentration is interpreted as a strategy for D. galeata to maximize its assimilation rate at given food concentrations. Key-words: Assimilation efficiency, assimilation rate, carbon budget, Cladocera, Daphnia galeata, food concentration, gross growth efficiency, net growth efficiency, zooplankton

Effects of food concentration on egg-production rates of two species of Pseudocalanus: laboratory observations

Experiments to determine the relationship between instantaneous egg-production rate and food concentration were carried out on Pseudocalanus newmani Frost and Pseudocalanus moultoni Frost from Puget Sound, Washington. The animals were fed a wide range of concentrations (0–300 μgC · 1 −1) of the diatom Thalassiosira weissflogii (Grunow) Fryxell et Hasle. Despite similar morphology and size, P. newmani and P. moultoni appear to have intrinsically different responses in egg production to food concentration. P. newmani reached a maximum egg-production rate at low food concentrations (50 μgC·1 −1) which can explain the observed year-round production of eggs of P. newmani in Puget Sound. In contrast, P. moultoni exhibited a more gradual increase in egg production with increasing food concentration which indicates P. moultoni is more sensitive to low food levels than is P. newmani. However, at high food concentrations, P. moultoni reached a significantly higher egg-production rate than did P. newmani. Only food concentration affected the egg-production rate of both species in these experiments as opposed to the size and condition of the animals.

Effect of food concentration on gut evacuation of Daphnia pulicaria and Daphnia longispina measured by the fluorescence technique

(1988). Effect of food concentration on gut evacuation of Daphnia pulicaria and Daphnia longispina measured by the fluorescence technique. SIL Proceedings, 1922-2010: Vol. 23, No. 4, pp. 2050-2055.

A kinetic analysis of hybridoma growth and metabolism in batch and continuous suspension culture: Effect of nutrient concentration, dilution rate, and pH

Hybridomas are finding increased use for the production of a wide variety of monoclonal antibodies. Understanding the roles of physiological and environmental factors on the growth and metabolism of mammalian cells is a prerequisite for the development of rational scale-up procedures. An SP2/0-derived mouse hybridoma has been employed in the present work as a model system for hybridoma suspension culture. In preliminary shake flask studies to determine the effect of glucose and glutamine, it was found that the specific growth rate, the glucose and glutamine metabolic quotients, and the cumulative specific antibody production rate were independent of glucose concentration over the range commonly employed in cell cultures. Only the specific rate of glutamine uptake was found to depend on glutamine concentration. The cells were grown in continuous culture at constant pH and oxygen concentration at a variety of dilution rates. Specific substrate consumption rates and product formation rates were determined from the steady state concentrations. The specific glucose uptake rate deviated from the maintenance energy model(1) at low specific growth rates, probably due to changes in the metabolic pathways of the cells. Antibody production was not growth-associated; and higher specific antibody production rates were obtained at lower specific growth rates. The effect of pH on the metabolic quotients was also determined. An optimum in viable cell concentration was obtained between pH 7.1 and 7.4. The viable cell number and viability decreased dramatically at pH 6.8. At pH 7.7 the viable cell concentration initially decreased, but then recovered to values typical of pH 7.1-7.4. Higher specific nutrient consumption rates were found at the extreme pH values; however, glucose consumption was inhibited at low pH. The pH history also influenced the behavior at a given pH. Higher antibody metabolic quotients were obtained at the extreme pH values. Together with the effect of specific growth rate, this suggests higher antibody production under environmental or nutritional stress.

Simultaneous Measurement of the Effect of Food Concentration on Assimilation and Respiration in Daphnia magna Straus

Simultaneous Measurement of the Effect of Food Concentration on Assimilation and Respiration in Daphnia magna Straus