Maximum Biomass Density Research Articles

Culture of the red alga Sarconema filiforme in open waters and hybrid carrageenan from the cultivated seaweeds

This is a first time report on the successful cultivation of the red alga Sarconema filiforme, employing floating rafts along the south-east coast of India, with an associated study of carrageenan content. Experiments were carried out on seasonality of growth rate and biomass of S. filiforme for 30 months, from August 2010 to January 2013. Harvest was done at the end of 25-day growth. In addition, experiments were also carried out optimizing harvests at the end of different duration of culture period (i.e. 20-, 25- and 30-day culture), and measurements were made at different localities (e.g. Ervadi and Thonithurai). Maximum biomass density (2.28 ± 0.03 kg fresh wt. m−2) and daily growth rates (DGR; 11.63 ± 0.06 %) were found from August to September each year, during the study, and these values were significantly different. Harvesting at the end of 25-day duration of culture period resulted in a maximum biomass (i.e. 4.24 ± 0.95 kg fresh wt. m−2), while 20-day duration of culture period showed higher DGR i.e. 13.20 ± 0.20 % which were significantly different from those plants harvested after 30 days. The range of biomass (i.e. 2.22 to 6.46 kg fresh wt. m−2) and DGR (i.e. 5.0 to 10.91 %) was higher at Ervadi than at Thonithurai site and was significantly different (P < 0.001). Physico-chemical analyses, infra-red and 13C nuclear magnetic resonance (NMR) spectral analyses of extracted carrageenan revealed the presence of hybrid lambda and iota carrageenan. The carrageenan yield from the cultivated material was higher than that of the wild stock of S. filiforme of Indian waters. The results of the study revealed that the peak growth period of S. filiforme was between September and December. Harvesting at the end of the 25-day growth period was more ideal. This study further revealed that production of better strains having hybrid, sulphated galactan, with higher yield and rheological properties the same as the wild stocks, could be possible through cultivation.

Wastewater from Instant Noodle Factory as the Whole Nutrients Source for the Microalga Scenedesmus sp. Cultivation

Cultivation of microalgae using wastewater exhibits several advantages such as nutrient removal and the production of high valuable products such as lipid and pigments. With this study, two types of wastewater from instant noodle factory; mixed liquor suspended solids (MLSS) and effluents after sedimentation tank were investigated for green microalga Scenedesmus sp. cultivation under laboratory condition. Optimal wastewater dilution percentage was evaluated in 24 wells microplate. MLSS and effluent without dilution showed the highest specific growth rate (μ) of 1.63±0.11 day－1 and 1.57±0.16 day－1, respectively, in which they were significantly (p < 0.05) higher than Scenedesmus sp. grown in BG11 medium (1.08±0.14 day－1). Ten days experiment was also conducted using 2000 ml Duran bottle as culture vessel under continuous light at approximately 5000 lux intensity and continuous aeration. It was found that maximum biomass density of microalgae cultivated in MLSS and effluent were 344.16 ± 105.60 mg/L and 512.89 ± 86.93 mg/L respectively and there was no significant (p < 0.05) difference on growth to control (BG11 medium). Moreover, cultivation microalgae in wastewater could reduce COD in wastewater by 39.89%-73.37%. Therefore, cultivation of Scenedesmus sp. in wastewater from instant noodle factory can yield microalgae biomass production and wastewater reclamation using photobioreactor simultaneously.

Flashing Light as Growth Stimulant in Cultivation of Green Microalgae, Chlorella sp. Utilizing Airlift Photobioreactor

One of the main limitations of productivity in photobioreactor is the inefficient conversion of the available light into biomass. Photoautotrophic cells such as microalgae only absorb a small fraction of supplied illumination due to limitation of its photosystem's (PS) absorbing rate. However, phenomenon of Flashing Light Effect (FLE) allows microalgae to utilize strong light exceptionally through intermittent exposure. Exposure of strong light at correct frequency of light and dark photoperiod would allow two pigment-protein complexes, PSI and PSII to be at the equilibrium mid-point potential to allow efficient light conversion. Narrow range of optimum frequency is crucial since overexposure to strong light would injured photosynthetic apparatus whereas longer dark period would contributed to loss of biomass due to triacylglycerol metabolism. The behaviour of microalgae towards various illumination conditions of FLE was determined at batch Photobioreactor (PBR) by varying the aeration flow rate: 16.94, 33.14 and 49.28 mL sec(-1) which yield, respectively the light exposure time of 3.99, 1.71 and 1.1 seconds per cycle. Maximum cell density in FLE-PBR was significantly higher at the exponential phase as compared to the continuously illuminated culture (p = 5.62 x 10(-5), a = 0.05) under the flow rate of 25.07 mL sec(-1). Maximum cell density yield of FLE-PBR and continuously illuminated PBR was, respectively 3.1125 x 10(7) and 2.947 x 10(7) cells mL(-1). Utilization of FLE as an innovative solution to increase the efficiency of microalgae to convert light into chemical energy would revolutionize the microalgae culture, reduce the time for cultivation and produce higher maximum biomass density.

Pilot Production of Hatchery-Reared Summer Flounder Paralichthys dentatus in a Marine Recirculating Aquaculture System: The Effects of Ration Level on Growth, Feed Conversion, and Survival

Pilot-scale trials were conducted to evaluate growout performance of hatchery-reared summer flounder fingerlings in a state-of-the-art recirculating aquaculture system (RAS). The outdoor RAS consisted of four 4.57-m dia × 0.69-m deep (vol. =11.3 m3) covered, insulated tanks and associated water treatment components. Fingerlings (85.1 g mean initial weight) supplied by a commercial hatchery were stocked into two tanks at a density of 1,014 fish/tank (7.63 kg/m3). Fish were fed an extruded dry floating diet consisting of 50% protein and 12% lipid. The temperature was maintained between 20 C and 23 C and the salinity was 34 ppt. Under these conditions, growth, growth variation (CVwt), feed utilization, and survival of fish fed to 100% and 82% of a satiation rate were compared. Due to clear changes in growth patterns during the study, data was analyzed in three phases. During phase 1 (d 1–d 196), fish showed rapid growth, reaching a mean weight of 288 g ± 105 and 316 g ± 102, with a CVwt of 0.36 and 0.32 and FCR's of 1.38 and 1.36 in the subsatiation and satiation groups, respectively. During phase 2 (d 196–d 454), fish displayed slower growth reaching mean weights of 392 g ± 144 and 436 g ± 121, with a CVwt of 0.37 and 0.28, and increasing FCR's of 3.45 and 3.12 in the subsatiation and satiation groups, respectively. During phase 3 (d 454–d 614), fish showed little growth reaching mean weights of 399 g ± 153 and 440 g ± 129, with a CVwt of 0.38 and 0.29 in the subsatiation and satiation groups, respectively. Over the entire growout period (d 1–d 614), feed conversion ratios were 2.39 and 2.37 and survival was 75% and 81 % in the subsatiation and satiation treatments, respectively. The maximum biomass density reached during the study was 32.3 kg/m3. The satiation feed rate was superior to the 82% satiation rate, since it maximized growth rates, with no effect on FCR. The higher CVwt in the subsatiation group suggests increased competition for a restricted ration led to a slower growth with more growth variation. The decrease in growth in phases 2 and 3 was probably related to a high percentage of slower growing male fish in the population and the onset of sexual maturity. This study demonstrated that under commercial scale conditions, summer flounder can be successfully grown to a marketable size in a recirculating aquaculture system. Based on these results, it is recommended that a farmer feed at a satiation rate to minimize growout time. More research is needed to maintain high growth rates through marketable sizes through all-female production and/or inhibition of sexual maturity.

The kinetics of Lagenidium giganteum growth in liquid and solid cultures

Production of the mosquito biolarvacide Lagenidium giganteum in solid culture has been proposed as an economic alternative to production in liquid culture because of observations of improved shelf life and efficacy upon storage. Understanding the differences between these production systems and estimating growth rate in solid culture are important for commercialization. In order to address these needs a logistic model was developed to describe the growth kinetics of L. giganteum produced in solid and liquid cultures. Kinetic parameters in the logistic model were estimated by nonlinear regression of CO2 evolution rate (CER) and biomass data from solid and liquid cultivation experiments. Lagenidium giganteum biomass was measured using DNA extracted directly from samples. The logistic model was fit to experimental biomass and CER data with low standard errors for parameter estimates. The model was validated in two independent experiments by examining prediction of biomass using on-line CER measurements. There were significant differences between maximum biomass density, maintenance coefficients, and specific growth rates for liquid and solid cultures. The maximum biomass density (mg dw ml-1) was 11 times greater for solid cultivation compared with liquid cultivation of L. giganteum; however, the maintenance coefficient (mg CO2 h-1 (mg dw)-1) was six times greater for liquid cultivation than in solid cultivation. The specific growth rate at 30 degrees C was approximately 30% greater in liquid cultivation compared with solid cultivation. Slower depletion of substrate and lower endogenous metabolism may explain the longer shelf life of L. giganteum produced in solid culture. A simple logistic model was developed which allows real-time estimation of L. giganteum biomass from on-line CER measurements. Parameter estimates for liquid and solid cultivation models also elucidated observations of longer shelf life for production in solid culture.

Evaluation of Mut+ and MutS Pichia pastoris Phenotypes for High Level Extracellular scFv Expression under Feedback Control of the Methanol Concentration

Extracellular secretion of over 4 g x L(-1) of the A33 scFv antibody fragment was achieved in Pichia pastoris at the 10 L bioreactor scale using minimal medium and feedback control of the methanol concentration. Since methanol acts as both inducer and carbon source, its close regulation is a crucial factor in achieving optimal fermentation conditions. The antibody fragment production levels of both Mut+ and MutS phenotypes were compared in a bioreactor under closed-loop PID control of the methanol level. As expected, the MutS phenotype has a growth rate lower than that of the Mut+ (0.37 vs 1.05 d(-1)) when growing under methanol. However, protein productivity and cell yield on substrate are almost double that of the Mut+ (18.2 vs 9.3 mg A33 sc per gram of methanol). Induction at wet cell weight of 350 g x L(-1) for the MutS also has a positive effect on the final product concentration. Both Mut+ and MutS phenotypes reach a maximum biomass density around 450 g x L(-1) wet cell weight, independent of methanol concentration, reactor scale, or induction density. This reactor configuration allows for reproducible fermentation schemes with different Pichia pastoris phenotypes with AOX promoters, without prior knowledge of the culture growth parameters.

Growth dynamics and biomass allocation of Eleocharis sphacelata at different water depths: observations, modeling, and applications

Imbalanced biomass allocation patterns in emergent aquatic plants to above and below-ground structures as a response to climatic variations and water depth were investigated on the basis of observation of three stable homogeneous populations established under different water regimes and climatic environments in Goulburn and Ourimbah, New South Wales, Australia, from August 2003 to December 2004. The growth of shoots depended on water inundation-drawdown patterns and climatic variations. Shoot density was greater in shallow water but with shorter shoot length and less maximum above-ground biomass density than for plant stands in deep water. Deep-water populations attained higher below-ground biomass with higher above to below-ground biomass ratio than for the shallow-water population. Translocation of carbohydrate reserves between above and below-ground organs in deep-water populations were mostly downward throughout the year whereas the depletion–recharge pattern varied seasonally in shallow water populations. Shoots of deep-water populations grew year-round whereas in shallow water shoots died off after recession of the water level with no re-growth afterward, showing that Eleocharis sphacelata is better adapted to deep water and is stressed under shallow-water conditions. A mathematical model was formulated to describe the growth patterns of E. sphacelata and subsequently to predict the effect of water depth on production. Model simulations are in satisfactory agreement with observed patterns of growth. The model also predicts that maximum production decreases sharply with increasing water depth.

Continuous plug‐flow bioreactor: Experimental testing with Pseudomonas putida culture grown on benzoate

The goals of this work were to test the feasibility of a continuous plug-flow (PF) bioreactor and to compare the growth in the PF bioreactor to that in a batch bioreactor. A culture of Pseudomonas putida was pumped through a tube made of Teflon with varying residence times. The culture was aerated by pumping of air simultaneously with liquid medium to provide air bubbles along the tubular culture. When the residence time in the PF bioreactor was greater than the time needed to reach the stationary phase in batch mode, the maximum biomass density reached in PF mode was the same as the maximum density reached in the batch bioreactor, and benzoate (the only carbon and energy source) was completely consumed. The drawbacks for practical application of PF were found to be fluctuations of cell concentration in the outflow cultural liquid due to cell aggregation, significant cell adhesion to the inner wall of Teflon tubing, and inadequate aeration.

Distribution, Stand Structure and Yearly Biomass Fluctuation of Elodea nuttallii, an Alien Species in Lake Biwa. Studies of Submerged Macrophyte Communities in Lake Biwa(3).

The areal distribution, stand structure and biomass of pure stands of Elodea nuttallii, an alien species of water weed invading Lake Biwa since 1961, were studied with emphasis on the remarkable yearly fluctuation in its biomass. The total area covered by the Elodea community was estimated at 895 ha, based on a complete lake survey in 1990 using sonar detection along a number of line transects. Underwater biomass samplings were carried out at two different depths in the northernmost part of the lake during two successive years, representing a light crop year (1988) and a heavy crop year (1989). The maximum biomass and stem density at the shallower site (depth 3 m) in 1989 amounted to 723g dry wt. m-2 and 4, 960 stems m-2, respectively. Those in 1988 were only 68% and 60% of the corresponding values of 1989. Both biomass and stem density decreased at the deeper sites (depth 5m), with the latter remaining fairly constant in both years. A comparison of environmental factors between light and heavy crop years indicated that a mild winter with a minimum monthly temperature above 8°C combined with sufficient sunshine in early spring favored the growth of overwintering plants from which new shoots were produced vegetatively. This resulted in greater biomass production in the following season.

Morphological traits and spatial heterogeneity of aquatic plants along sediment and depth gradients, Lake Geneva, Switzerland

The morphological response and distribution of Potamogeton pectinatus L., P. lucens L. and P. perfoliatus L. were investigated in relation to sediment and depth gradients within the littoral zone of Lake Geneva. Biomass, maximum shoot length, shoot biomass and biomass density were the plant traits analyzed, together with sediment characteristics: texture, water content, organic nitrogen and carbon, and exchangeable phosphorus and potassium. The relationships between (i) depth and sediment characteristics vs. species distribution and (ii) depth and sediment characteristics vs. plant traits were first studied. Regression models for the biomass and the shoot length of each species are proposed. These models are applied in a related article (Lehmann et al., 1997) in order to study the relationship between plant traits vs. species distribution through a Geographic Information System modeling. Besides the fact that P. pectinatus was more often found in sediments with higher organic content, no direct relationships were found between sediment characteristics and species distribution. Neither could the presence of patches of bare substrate be explained by differences in sediment characteristics. The effect of the sediment characteristics on plant growth showed in general a negative influence of organic matter content (except for P. pectinatus), and a positive influence of the fine texture and phosphorus. P. pectinatus grew better in shallower water, P. lucens appeared to have the best competitive abilities and P. perfoliatus performed best at deeper sites.

Production and population ecology of Phyllospadix iwatensis Makino. II. Comparative studies on leaf characteristics, foliage structure and biomass change in an intertidal and subtidal zone

A seagrass in Japan, Phyllospadix iwatensis Makino, is distributed in the lower intertidal zone and upper subtidal zone making a dense population on the Choshi coast, Japan. Intertidal P. iwatensis is able to receive sufficient light for photosynthesis but experienced severe exposure to the air, which decreased a large amount of aboveground biomass in April to June (i.e. the daytime exposure season). Subtidal P. iwatensis was never exposed throughout the year and the aboveground biomass increased gradually over the daytime exposure season. However, the maximum aboveground biomass and shoot density of the subtidal plant never exceeded that of the intertidal plant. The dense foliage, large aboveground biomass and high shoot density of both intertidal and subtidal plants is likely to be an adaptation to heavy water movement, but the subtidal plants always received insufficient light for photosynthesis as a result of having dense foliage, particularly in turbid water. In choppy and swell sea, P. iwatensis did not seem to be adapted to growing in the subtidal zone where there was shortage of light.

The diversity, abundance and biomass of termites under differing levels of disturbance in the Mbalmayo Forest Reserve, southern Cameroon

This paper presents data on the abundance, biomass and species richness of termites in the Mbalmayo Forest Reserve, southern Cameroon. Five plots of differing disturbance level (near primary forest, old secondary forest, young plantation, weededChromolaenafallow, and completely cleared forest) were sampled for termites in two successive years (July 1992 and July 1993, giving a total of ten sampling areas, plus one in the completely cleared plot in November 1992). A stratified sampling regime of soil pits, wood samples, mound samples and soil scrape samples was used. Estimated abundance and biomass were extremely high in the near primary and old secondary plot (maximum estimated abundance, old secondary sampling area 1, 10488 m-2, maximum biomass density, near primary sampling area 1,123.2 g m-2). In all cases termite abundance was highly clumped. Disturbance had apparently little effect on termite abundances and biomass in forested plots, but there were clear reductions in abundance and biomass in the cleared plots. In the completely cleared plot, abundance and biomass fell sharply from year 1 to year 2, presumably because colonies left after clearance had dried out and died. There were large differences in the taxonomic-, nesting- and feeding-group composition of the plots, with soil feeding termites being especially strongly affected by disturbance. The sources of error associated with this sampling programme are discussed. It is argued that the near primary forest plot may have higher microhabitat and concomitant termite assemblage heterogeneity than the more disturbed plots. In most cases over 90 % of the overall abundance in a sampling area was due to a few species; extinction, and will make areas. This may be due to the unpredictable dynamics of colony foundation and extinction, and will make estimations of the effect of termites on overall ecosystem processes (from abundance and biomass data alone) problematical. There is no evidence of immigration of savanna termites into the forest reserve, and thus cleared areas have depauperate forest assemblages. It is concluded that this is the most accurate estimation of termite assemblage parameters yet attempted.

Cell Damage and Oxygen Mass Transfer during Cultivation of Nicotiana tabacum in a Stirred‐Tank Bioreactor

AbstractCell damage and oxygen mass transfer were investigated during the batch culture of Nicotiana tabacum (tobacco) cells in a 3‐L Applikon stirred‐tank bioreactor equipped with a marine‐blade impeller. Total cell density, % culture viability, viable cell density, and kLa in the culture were measured over a 24‐day cultivation period at impeller speeds of 100–325 rpm under a fixed air flow of 0.43 wm and a temperature of 27 °C. The maximum total biomass density decreased from 11.8 g of dry cell weight (DCW)/L at 100 rpm to 8.6 g of DCW/L at 325 rpm. The net specific biomass production rate of viable cells (μv) during the exponential phase and the viable cell death rate (kd) during the stationary phase were estimated from semilog plots of viable cell density vs cultivation time. Values for μv decreased from 0.175 to 0.077 day−1 whereas values for kd increased from 0.042 to 0.109 day−1 with increasing impeller tip speed (from 24 to 77 cm/s), clearly showing that increasing agitation intensity increased the rate of cell damage. The effect was most pronounced at tip speeds of 24–60 cm/s. With respect to oxygen mass transfer, culture kLa values were about 10–20% higher than their corresponding initial kLa° values, but as the cell density increased, the values for kLa ultimately decreased. Despite the reduction in oxygen mass transfer rates, at impeller speeds of 100–325 rpm and an aeration rate of 0.43 wm, oxygen starvation was not observed. Therefore, the reduction in biomass productivity can be attributed to cell damage by hydrodynamic forces and not by inadequate oxygen mass transfer.

Start-feeding of Atlantic salmon in a water recycling plant

A water recycling plant for Atlantic salmon smolt production has been developed and tested in pilot scale. The plant consists of a micro-strainer with a sieve opening of 0·063 mm, followed by two aerated submerged biological filters. The recycled water is then pumped through a dual media sand filter and a disinfection unit. Make-up water is added ahead of a heat exchanger, before the water flows through packed column aerators and back to the fish tanks. CaCO 3 slurry is used for pH-control. The plant is equipped for continuous monitoring of temperature, pH, dissolved oxygen and turbidity. Tests with start-feeding of Atlantic salmon showed daily growth of 3·8–4·0% at 13–14°C and 0·8–1·0 g feed/g fish growth. The recycled water was of good quality, with median concentrations of 0·28 mg litre −1 NH 4 +N, 0·06 mg litre −1 NO 2 −N, 0·6 mg litre −1 SS and 8 mg litre −1 COD. The lowest consumption of make-up water was 2% of the flow or 25% of the total volume of the system per day. Maximum biomass density in the fish tanks was about 20 kg m −3 of water.

NH+/4‐N assimilation by Rhodobacter capsulatus ATCC 23782 grown axenically and non‐axenically in N and C rich media

Assimilation of NH+/4‐N and formation of cell biomass in Rhodobacter capsulatus ATCC 23782 were studied in batch cultures as a function of N and C concentration and light intensity. Growth occurred satisfactorily up to N and C levels of 1.2 and 6.0g/1, respectively. The maximum biomass density achieved was 2.3 g biomass‐C/l at 0.8 g N/l and 4.0g C/l. Media containing initial C/N ratios of 5 provided good growth and almost complete assimilation and recovery of NH+/4‐N and lactate‐C, respectively. A light intensity of about 120 μE/m2/s was adequate for efficient growth. At low levels of NH+/4‐N (&lt;0.05 g N/l), the photobacterium could not maintain dominance under non‐axenic growth conditions. Chloroxuron was necessary to prevent algal overgrowth. At concentrations of 0.2 and 0.4 g NH+/4‐N/l, the photo‐bacterium maintained dominance over several months under the appropriate conditions of temperature (30°C), light intensity (120μE/m2/s), carbon supply (C/N = 5) and cell residence time (5.5d). The protein of Rhb. capsulatus ATCC 23782 was rich in essential amino acids.