Summary

Biosynthesis and synthetic biology explore the enzymatic formation of biological molecules and the design, engineering, and reconstruction of biological systems. This collection covers biosynthetic pathways, enzyme-mediated reactions, metabolic engineering, genetic circuits, engineered microorganisms, cellular factories, genome editing, and the production of valuable compounds through programmable biological processes.

Expand All
Entries
Topic Review
Plant Bioreactors
Plant bioreactors are controlled cultivation systems that maintain plant cells, tissues, organs, or organ-derived cultures while providing defined nutritional and physical conditions. The biological material may be suspended cells, hairy roots, shoots, embryos, or other organized structures producing biomass or specialized metabolites [1]. A plant bioreactor supplies liquid medium and regulates temperature, pH, gas exchange, mixing, and renewal of nutrients; illumination is added when photosynthetic or light-responsive material is used. Airlift, bubble-column, temporary-immersion, and mechanically agitated designs create different patterns of circulation and shear, affecting aggregation, differentiation, oxygen availability, and metabolite accumulation [2]. Plant cultures can be sensitive to mechanical stress and poor gas transfer, so vessel geometry and contact between tissue and medium must be selected carefully [1][3]. Operation may be batch, fed, or semi-continuous, with elicitors, precursors, hormones, or light changes used to redirect secondary metabolism. Evaluation includes growth rate, tissue quality, product concentration, genetic stability, contamination control, and reproducibility of harvested material [2][4].
  • 9
  • 25 Oct 2026
Topic Review
Fermentation Temperature
Fermentation temperature is the thermal condition imposed on a culture during a biological conversion process, expressed as a set point, range, or programmed time profile. It influences enzyme reaction rates, membrane properties, growth kinetics, product formation, gas solubility, and the balance between competing metabolic pathways [1]. A temperature shift can therefore change both biomass accumulation and the composition of metabolites or recombinant products. The measured value usually represents bulk broth temperature, whereas cells may experience local differences when heat generation, viscosity, or mixing limitations create gradients [2]. Temperature control combines metabolic heat generation with heat transfer through the vessel wall, cooling surfaces, evaporation, and incoming or outgoing streams [3][4]. The useful operating range is organism- and product-specific: temperatures that maximize growth may not maximize folding, secretion, aroma formation, or product stability. The profile is selected together with inoculum state, oxygen supply, pH, feeding, and harvest timing [5].
  • 3
  • 25 Oct 2026
Topic Review
Fermentation Engineering
Fermentation engineering applies transport phenomena, reaction engineering, and microbial physiology to the design and operation of cultivation processes. The engineering problem links cellular kinetics with vessel geometry, mixing, oxygen transfer, heat removal, rheology, sterilization, sampling, and product recovery . Reactor selection must match the organism and product because suspended microbes, filamentous fungi, plant cells, and immobilized catalysts impose different requirements for shear, circulation, gas dispersion, and biomass retention [1]. Scale-up cannot be achieved by enlarging dimensions alone: power input, mixing time, gas hold-up, and oxygen-transfer capacity change with vessel size and operating conditions [2][3]. Engineers therefore choose criteria such as constant power per volume, tip speed, oxygen-transfer rate, or mixing performance according to the biological constraint. Process design also specifies medium preparation, inoculation, control loops, contamination barriers, and harvest conditions. Analysis identifies bottlenecks that limit volumetric productivity, including substrate gradients, excessive viscosity, foaming, heat accumulation, or insufficient gas transfer [1][3][4]. It can also protect temperature-sensitive product structures.
  • 5
  • 25 Oct 2026
Topic Review
Fermentation Monitoring
Fermentation monitoring is the systematic acquisition and interpretation of measurements that describe the physical, chemical, and biological state of a culture during operation. Online instruments can follow temperature, pH, pressure, agitation, gas flow, dissolved oxygen, oxygen uptake, carbon dioxide evolution, and exhaust-gas composition without removing broth [1]. At-line and off-line analyses provide variables that are not yet measured continuously, including cell density, viable biomass, residual substrates, organic acids, product concentration, metabolites, and contaminants [2]. The measurements form time series that reveal growth phases, substrate exhaustion, oxygen limitation, metabolic shifts, and the approach of a harvest endpoint. Monitoring strategy is selected according to the organism, process risk, sensor response time, sampling burden, and the decisions that must be made from the data [3]. A single bulk measurement can conceal gradients caused by imperfect mixing, especially in large vessels or highly viscous cultures. For this reason, monitoring may combine direct sensors, soft sensors, spectroscopy, imaging, and mass-balance calculations [4].
  • 6
  • 25 Oct 2026
Topic Review
Fermentation Control
Fermentation control is the coordinated adjustment of process inputs so that a biological culture follows a specified operating trajectory. A control loop combines a measured variable, a target or control law, and an actuator that changes the vessel environment. Typical manipulated inputs include agitation, gas flow, feed rate, temperature, pH-control reagent, pressure, and antifoam addition [1]. Feedback control responds to deviations in measured temperature, dissolved oxygen, pH, or residual substrate, whereas feedforward and model-based strategies use an expected process response to anticipate changes [2]. The selected control objective may be stable growth, oxygen-limited production, suppression of overflow metabolites, maintenance of a physiological state, or reproducible product quality [3]. Sensor delay, calibration drift, sampling frequency, mixing heterogeneity, and actuator limits can make the measured value differ from the condition experienced by cells. Effective control therefore links instrumentation with a process model and a biologically meaningful objective. Control performance is judged by trajectory stability and product reproducibility [1][2][4].
  • 6
  • 25 Oct 2026
Topic Review
Fermentable Sugars
Fermentable sugars are carbohydrate substrates that a particular microorganism or cell system can transport and convert through pathways that generate energy and defined end products under specified conditions. The category includes monosaccharides such as glucose and xylose, disaccharides such as sucrose and maltose, and hydrolysis products released from starch, cellulose, or hemicellulose [1]. Fermentability is therefore organism- and process-specific: a sugar must be chemically accessible, recognized by a transporter, phosphorylated or otherwise activated, and connected to a catabolic route that supports cellular redox and energy balance [2]. Mixed hydrolysates may contain sugars that are consumed sequentially because of carbon catabolite repression, transporter competition, or differences in pathway regulation [3]. Pretreatment can increase sugar release, but it may also generate furfural, hydroxymethylfurfural, phenolics, or organic acids that inhibit growth and fermentation. In a bioprocess, the relevant sugar pool is consequently determined by feedstock composition, hydrolysis efficiency, uptake capacity, regulatory state, and inhibitor tolerance rather than by carbohydrate concentration alone [1][4].
  • 10
  • 25 Oct 2026
Topic Review
Batch Fermentation Techniques
Batch fermentation techniques are procedures for carrying out a discrete cultivation run from inoculation to harvest without a continuous replacement of culture broth [1]. A defined volume of medium is charged before inoculation, and the culture then progresses through lag, growth, production, and decline phases as nutrients are consumed and metabolites accumulate [1][2]. The technique includes preparation and sterilization of the medium, inoculum transfer, regulation of temperature and pH, control of aeration and agitation when required, sampling, and selection of a harvest criterion [2]. In a strict batch, no feed is added after inoculation, although pH-control reagents, antifoam, or gases may still enter the vessel. The resulting time trajectory reflects the starting composition, inoculum physiology, vessel environment, and organism-specific responses to nutrient depletion and product inhibition [1][3]. Batch operation is widely used for screening, seed-train development, food and beverage fermentations, and processes in which a reproducible finite run is preferable to long-term steady-state operation [4].
  • 8
  • 25 Oct 2026
Topic Review
Fed-Batch Fermentation
Fed-batch fermentation is a cultivation mode in which one or more medium components are added during growth while culture broth is retained until harvest. The initial charge establishes the starting volume and nutrient environment; the feed then changes substrate availability, osmolarity, volume, and dilution of soluble products [1]. Feed profiles may be constant, exponential, pulse-based, or adjusted from measurements such as dissolved oxygen, respiratory activity, residual substrate, or biomass estimates [2]. Deliberate limitation of a carbon or nitrogen source can restrain overflow metabolism and redirect cellular resources toward biomass, recombinant protein, organic acids, or secondary metabolites [1][3]. Because the working volume rises, the process also changes oxygen-transfer demand, mixing time, heat removal, and final product concentration [2][4]. A fed-batch run therefore requires coordinated decisions about feed composition, pump accuracy, addition timing, antifoam, pH control, and the harvest endpoint. The feed can also be stopped or redirected when the culture reaches a defined physiological state [5].
  • 15
  • 25 Oct 2026
Topic Review
Stirred-Tank Bioreactor
A stirred-tank bioreactor is a mechanically agitated vessel designed to support controlled biological processes by maintaining the mixing, mass transfer, and physicochemical conditions required for cellular growth, microbial metabolism, or enzymatic activity [1][2]. Its principal components include a cylindrical or similarly configured vessel, an agitation assembly comprising a drive mechanism, shaft, and one or more impellers, and, in many configurations, internal baffles that regulate fluid circulation. Gas-distribution components, such as spargers, may be incorporated to introduce air or other process gases and facilitate gas–liquid mass transfer [1][3]. The bioreactor integrates fluid mixing, heat transfer, gas exchange, and process monitoring within a defined reaction volume. Instrumentation commonly measures temperature, pH, and dissolved oxygen, while associated control systems regulate agitation speed, gas flow, temperature, and the addition of acids, bases, nutrients, or other process reagents according to specified operating conditions [2][4]. The vessel may be constructed from glass, stainless steel, or compatible polymeric materials and configured for batch, fed-batch, or continuous operation. Biological material may be cultivated as suspended cells or microorganisms, or the vessel may contain enzymes or other biocatalysts participating in biochemical reactions. The internal geometry, impeller configuration, operating conditions, and liquid properties collectively determine the hydrodynamic environment, mixing characteristics, oxygen-transfer capacity, and distribution of nutrients and metabolites within the culture volume [1][3][4].
  • 7
  • 24 Oct 2026
Topic Review
Enzyme Biosynthesis
Enzyme biosynthesis is the cellular production and maturation of enzyme molecules. Protein-enzyme synthesis begins with translation of an encoding messenger RNA, followed by formation of the molecular features needed for catalysis. For iron–sulfur enzymes, specialized machinery assembles the cluster on a scaffold before transfer to the protein [1][2]. Cofactor insertion and protein maturation are coordinated processes involving multiple accessory components [3]. Enzymes entering the secretory pathway undergo folding, assembly, and modifications in the endoplasmic reticulum, including disulfide-bond formation or glycosylation where appropriate [4]. Organellar enzymes can also undergo proteolytic removal of targeting sequences or other maturation segments after transport [5]. These reactions convert the newly synthesized polypeptide into its functional molecular form and establish the catalytic groups, subunit contacts, and cellular location required for activity [2].
  • 12
  • 24 Oct 2026
  • Page
  • of
  • 9

Other Entry Collections

>>