Bioprocess Monitoring and Control

Process monitoring and control are fundamental to all processes; this holds especially for bioprocesses, due to their complex nature. Usually, bioprocesses deal with living cells, which have their own regulatory systems. It helps to adjust the cell to its environmental condition. This must not be the optimal condition that the cell needs to produce whatever is desired. Therefore, a close monitoring of the cell and its environment is essential to provide optimal conditions for production. Without measurement, no information of the current process state is obtained. In this book, methods and techniques are provided for the monitoring and control of bioprocesses. From new developments for sensors, the application of spectroscopy and modelling approaches, the estimation and observer implementation for ethanol production and the development and scale-up of various bioprocesses and their closed loop control information are presented. The processes discussed here are very diverse. The major applications are cultivation processes, where microorganisms were grown, but also an incubation process of bird’s eggs, as well as an indoor climate control for humans, will be discussed. Altogether, in 12 chapters, nine original research papers and three reviews are presented

Identification of supraoptimal temperatures in juvenile blueback herring (\u3cem\u3eAlosa aestivalis\u3c/em\u3e) using survival, growth rate and scaled energy reserves

For young fishes, growth of somatic tissues and energy reserves are critical steps for survival and progressing to subsequent life stages. When thermal regimes become supraoptimal, routine metabolic rates increase and leave less energy for young fish to maintain fitness-based activities and, in the case of anadromous fishes, less energy to prepare for emigration to coastal habitats. Thus, understanding how energy allocation strategies are affected by thermal regimes in young anadromous fish will help to inform climate-ready management of vulnerable species and their habitat. Blueback herring (Alosa aestivalis) are an anadromous fish species that remain at historically low population levels and are undergoing southern edge-range contraction, possibly due to climate change. We examined the effects of temperature (21°C, 24°C, 27°C, 30°C, 33°C) on survival, growth rate and energy reserves of juveniles collected from the mid-geographic range of the species. We identified a strong negative relationship between temperature and growth rate, resulting in smaller juveniles at high temperatures. We observed reduced survival at both 21°C and 33°C, increased fat and lean mass-at-length at high temperatures, but no difference in energy density. Juveniles were both smaller and contained greater scaled energy reserves at higher temperatures, indicating growth in length is more sensitive to temperature than growth of energy reserves. Currently, mid-geographic range juvenile blueback herring populations may be well suited for local thermal regimes, but continued warming could decrease survival and growth rates. Blueback herring populations may benefit from mitigation actions that maximize juvenile energy resources by increasing the availability of cold refugia and food-rich habitats, as well as reducing other stressors such as hypoxic zones

Thermal responses of marine phytoplankton: Implications to their biogeography in the present and future oceans

Phytoplankton are ecologically significant as primary producers and as regulators of the biogeochemical cycle. However, some may form harmful algal blooms that are a global problem due to the production of toxins that pose a risk to public health, the environment, and our economy. Climate change poses a serious threat to phytoplankton communities. It is, therefore, crucial to advance our knowledge on how they respond to the changes in temperature that is projected to increase in the next decades. The main aim of this thesis is to investigate how temperature limits biogeography, growth, toxin production, and competition in marine phytoplankton. To achieve this aim, the thesis presents a series of chapters with independent objectives. In Chapter 2, I analysed a global dataset of species occurrence data to examine the global patterns in the realised thermal niche and geographic range of marine phytoplankton. In Chapter 3, I investigated the global patterns of thermal traits, thermal sensitivity, and exposure and vulnerability to warming in marine phytoplankton. In Chapter 4 and 5, I conducted laboratory experiments to examine the temperature dependence of growth and toxin production in marine dinoflagellates. In Chapter 6, I also conducted laboratory experiments to test the effect of increased temperature on growth and competition in marine phytoplankton using dinoflagellates as test organisms. The key results of this thesis are as follows: (1) the current distribution of marine phytoplankton is limited by temperature, (2) their thermal traits are contingent on their biogeography and phylogeny, (3) their growth and toxin production is affected by temperature, and (4) interspecific competition in dinoflagellates is altered by increasing temperature. The findings of this thesis advance our current predictive understanding of the ecological responses of marine phytoplankton to climate change

Modelling the effect of temperature on phytoplankton growth across the global ocean

International audiencePhytoplankton are ectotherms and are thus directly influenced by temperature. They experience temporal variation in temperature which results in a selection pressure. Using the Adaptive Dynamics theory and an optimization method, we study phytoplankton thermal adaptation (more particulary the evolution of the optimal growth temperature) to temperature fluctuations. We use this method at the scale of global ocean and compare two existing models. We validate our approach by comparing model predictions with experimental data sets from 57 species. Finally, we show that temperature actually drives evolution and that the optimum temperature for phytoplankton growth is strongly linked to thermal amplitude variations

Experimental and model-based analysis for optimizing Chromochloris zofingiensis growth from laboratory to plant scale

This thesis is focused on verifying large-scale feasibility of a hybrid chemical and biological process for CO2-fixation, combining carbon dioxide absorption by means of a carbonate-based solvent with microalgal sequestration, where CO2 is fed to the culture in bicarbonates form. A rigorous simulation is carried out using Aspen Plus process simulator to solve material and energy balances, and to check whether this process can be scaled-up at industrial level. The steam methane reforming plant data are taken as the starting point to set up the process simulation. The plant layout includes a first section where the carbon dioxide in the steam methane reforming tail gas is chemically absorbed by using a sodium carbonate aqueous solution. The liquid from the bottom of the column is then fed to the photobioreactor, microalgae are separated from water, which is recycled to the absorption column, after a suitable make up. The model kinetic parameters are obtained from experimental growth data of Arthrospira Platensis species measured in laboratory continuous cultivation systems, and takes into account the effect of temperature and light. Simulation results are used to calculate the volume of the photobioreactor and the irradiated area required, as a function of light intensity. Photosynthetic efficiency and electrical energy consumption are also evaluated. Eventually, a reactor design proposal is suggested, and costs related to energy supply to microalgae culture are presented.This thesis is focused on verifying large-scale feasibility of a hybrid chemical and biological process for CO2-fixation, combining carbon dioxide absorption by means of a carbonate-based solvent with microalgal sequestration, where CO2 is fed to the culture in bicarbonates form. A rigorous simulation is carried out using Aspen Plus process simulator to solve material and energy balances, and to check whether this process can be scaled-up at industrial level. The steam methane reforming plant data are taken as the starting point to set up the process simulation. The plant layout includes a first section where the carbon dioxide in the steam methane reforming tail gas is chemically absorbed by using a sodium carbonate aqueous solution. The liquid from the bottom of the column is then fed to the photobioreactor, microalgae are separated from water, which is recycled to the absorption column, after a suitable make up. The model kinetic parameters are obtained from experimental growth data of Arthrospira Platensis species measured in laboratory continuous cultivation systems, and takes into account the effect of temperature and light. Simulation results are used to calculate the volume of the photobioreactor and the irradiated area required, as a function of light intensity. Photosynthetic efficiency and electrical energy consumption are also evaluated. Eventually, a reactor design proposal is suggested, and costs related to energy supply to microalgae culture are presented

Development of a plasma sprayed ceramic gas path seal for high pressure turbine application

Development of the plasma sprayed graded, layered ZRO2/CoCrAlY seal system for gas turbine engine blade tip seal applications up to 1589 K (2400 F) surface temperature was continued. The effect of changing ZRO2/CoCrAlY ratios in the intermediate layers on thermal stresses was evaluated analytically with the goal of identifying the materials combinations which would minimize thermal stresses in the seal system. Three methods of inducing compressive residual stresses in the sprayed seal materials to offset tensile thermal stresses were analyzed. The most promising method, thermal prestraining, was selected based upon potential, feasibility and complexity considerations. The plasma spray equipment was modified to heat, control and monitor the substrate temperature during spraying. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capability of the thermal prestrain method to develop compressive residual stresses in the sprayed structure and (2) define the effect of spraying on a heated substate on abradability, erosion and thermal shock characteristics of the seal system. Thermal stress analysis, including residual stresses and material properties variations, was performed and correlated with thermal shock test results. Seal system performance was assessed and recommendations for further development were made

The physiological response of the Arctic haptophyte Phaeocystis pouchetii to marine heatwaves

Due to the ongoing global warming extreme weather events like marine heatwaves (MHWs) have already become more frequent and intense as well as longer lasting, and their probability of occurrence is projected to increase in the future, especially in the Arctic Ocean. MHWs can rapidly push a species beyond their usually experienced temperature range, often exceeding physiological tolerance thresholds. Furthermore, fluctuation between higher and lower temperatures associated with MHWs can induce metabolic mismatches between physiological subprocesses. Thus, MHWs could have worse effects on the performance of a species than those emanating from the mean temperature rise due to global warming. Despite this potential threat, knowledge on the impact of MHWs on Arctic phytoplankton is still scarce. In this master thesis project, I designed a laboratory experiment to investigate the physiological capacity of the Arctic key phytoplankton species Phaeocystis pouchetii to physiologically acclimate to heatwave scenarios. After pre-acclimation to experimental conditions at 3 °C, cells were rapidly exposed to two MHWs with an intensity of 6 °C for varying durations (MHW1: 6 days, MHW2: 10 days), followed by a 5-day recovery phase at 3 °C. The non-acclimated response to the MHW treatments was further compared to the acclimated response of cells experiencing continuous heat exposure of 6 °C for 3 weeks. The physiological performance of cells was investigated by assessing specific growth rates, elemental composition and cellular chlorophyll a content. Furthermore, photophysiology was assessed by fast repetition rate fluorometry (FRRF) measurements of variable chlorophyll fluorescence and intracellular levels of O2•- and H2O2 were determined by flow cytometric analysis. The results demonstrated that warming strongly stimulated growth rates in the short-term and reduced photosynthetic efficiency and triggered production of reactive oxygen species (ROS) in the long-term. Intracellular ROS levels reached a maximum after 6 days and declined thereafter, which was likely enabled by a highly effective antioxidant scavenging system and the water-water cycle. In the long-term, P. pouchetii was not able to maintain the stimulated growth rates observed shortly after the temperature rise, which could be explained by a reallocation of energy into ROS detoxification. Longer MHWs exerted more thermal stress on cells than shorter ones, as indicated by lower Fv/Fm values and decreased POC quota. Thermal acclimation of cells to continuous heat exposure (6 °C control) involved enhanced light absorption capacity by increasing cellular Chl a content, increased POC quota and rebalancing of intracellular ROS levels. A high capacity for ROS scavenging, but also elevated thresholds towards oxidative stress may thus play a pivotal role in this species’ resilience to increased VI thermal stress. However, thermal plasticity comes at a metabolic cost and reduced performance in the long-term, as indicated by lower growth rates of cultures acclimated to 6 °C compared to 3 °C. During the recovery at 3 °C after the MHWs, Chl a content decreased as an adjustment to reduce excitation pressure. In combination with the still upregulated detoxification mechanisms during MHW exposure, ROS levels declined. The cooling post-MHW therefore represented a relief to cells in regard to oxidative stress, but it nevertheless required reacclimation and reduced performance as indicated by the trend of declining growth rates during recovery. The overall effect of MHWs on the fitness of P. pouchetii was nevertheless only marginal and even though 6 °C seems to be positioned above its optimum temperature, it is still within its thermal tolerance range. The resilience of this species towards MHWs with an intensity of 6 °C might be explained by the adaptation to the warmer and fluctuating temperatures of the Fram Strait, where this strain was originally isolated or advection of this strain into the Arctic from lower latitudes. Even though maximizing growth does not seem to be the ecological strategy of P. pouchetii, it may nonetheless outcompete other species with lower thermal thresholds. In addition, the heteromorphic life cycle and high capacity for protection against oxidative stress may represent valuable strategies, that enable the ecological success of this species in the future Arctic Ocean

Modeling the temperature effect on the specific growth rate of phytoplankton: a review

International audiencePhytoplankton are key components of ecosystems. Their growth is deeply influenced by temperature. In a context of global change, it is important to precisely estimate the impact of temperature on these organisms at different spatial and temporal scales. Here, we review the existing deterministic models used to represent the effect of temperature on microbial growth that can be applied to phytoplankton. We first describe and provide a brief mathematical analysis of the models used in constant conditions to reproduce the thermal growth curve. We present the mechanistic assumptions concerning the effect of temperature on the cell growth and mortality, and discuss their limits. The coupling effect of temperature and other environmental factors such as light are then shown. Finally, we introduce the models taking into account the acclimation needed to thrive with temperature variations. The need for new thermal models, coupled with experimental validation, is argued

Hanging out with the cool frogs: Do operative and body temperatures explain population response to disease?

Batrachochytrium dendrobatidis (Bd) is a fungal pathogen causing amphibian population declines. Bd has a narrow thermal tolerance and requires moisture to survive. Differences in frog biology, pathogen biology or temperature and moisture conditions may determine population response to disease. Population responses to Bd vary among sites, habitats, species and populations. In the tropics, stream-dwelling species decline to a greater degree than forest species, yet not all stream species decline to extirpation and not all forest species survive. I hypothesized that variation in operative temperature (Te) or body temperature (Tb) might explain differences in host population change documented among sites, seasons, habitats, and species. I sampled three moist-forest Panamanian sites (elevation 375 - 1300 m) during 2.5 months of the 2008 wet season and four different moist-forest sites (elevation 400 - 1300 m) during 3 weeks of the 2008 dry season. I measured Te and Tb of anurans along stream and forest transects. Additional environmental variables such as height, substrate, canopy cover and sunfleck presence were measured concomitantly. I used analysis of covariance to determine whether these factors influenced Te and Tb. I compared frequency distributions of Tb and Te to a Bd thermal growth curve to determine: 1) whether temperatures above Bd\u27s critical thermal maximum were available to frogs, and 2) whether populations of species that have declined occupied habitats more frequently in Bd\u27s optimal thermal range than species that have not. Te and Tb differed among sites, with cooler temperatures at higher elevation. Te was cooler during the dry season yet the presence of sunflecks and open canopy had greater effect on Te during the dry season. Within a site, Te and Tb were not different between habitats. Within a site, Tb did not vary among species. Average Te and Tb for all sites fell within Bd\u27s thermal tolerance range, but the low elevation sites had Tb ranges extending above Bd\u27s critical thermal maximum. Although temperature may explain greater losses at higher elevations, I found no significant difference in operative temperatures between stream and forest habitats at any site which indicates that temperature alone does not explain greater losses of stream anurans. Species that have declined to extirpation elsewhere did not consistently have cooler body temperatures compared to surviving species. Within the Neotropics, moisture, instead of temperature, may explain patterns of Bd prevalence among seasons, habitats, and species