technology
what makes the microbotanics tick
What is the technology behind microbotanics?
Microbotanics levarages the unique properties of plant cells through a suite of techniques known colectively as Plant Cell Culture (PCC). These techniques enable the isolation, propagation, and cultivation of plant cells in a precisely regulated and nutrient-rich environment, independent of whole plants.
Plant Source
A part of a plant, such as a petal, leaf, root, stem, or fruit, is cut from the parent plant. In PCC this is referred to as an explant and marks the first step of the process. Serving as the initial source of cells, the explant responds to controlled conditions, enabling growth and development.
Callus Culture
When placed on a nutrient-rich solid medium with agar and plant signaling molecules, an explant develops a semi-loose mass of dedifferentiated cells referred to as the callus. Naturally formed in plants for wound healing, callus can divide or differentiate into various cell types. During this phase, callus lines are selected for rapid growth, high metabolite production, and genetic stability.
Suspension Culture
Selected calli are transferred to flasks containing liquid medium with nutrients and plant signaling molecules. The flasks are shaken, breaking the callus into small aggregates or single cells that grow and divide in suspension. At this stage, companies screen multiple cell lines to identify those that are suitable for large-scale production.
Scale-Up & Production
The suspension culture is gradually scaled from flasks to large tanks. These bioreactors may include stainless steel tanks, single-use plastic bags, or other systems designed to optimize nutrient distribution and gas exchange. For production, the cells are often first cultured under conditions that promote growth. Later, the conditions are adjusted, or specific signaling molecules are introduced, to stimulate the production of desired compounds in a process known as elicitation.
Harvesting & Downstream Processing
Once production is complete, plant cells are harvested and washed. If whole plant cells are used as an ingredient, they are either utilized directly or dried through methods like heating or freeze-drying. For products requiring plant cell extracts, the cells undergo extraction processes to isolate the desired compounds.
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Plant cell culture media - what's inside
PCC media typically consist of a completely defined mix of carbohydrates, salts, vitamins, and plant signaling molecules. They typically do not contain proteins and amino acids. In developed countries, bench-scale plant cell culture media for research purposes typically cost less than $1 per liter.
A typical PCC medium contains:
Carbohydrates
Sucrose, commonly derived from cane or beet sugar, is the most widely used carbohydrate source. To further reduce dependence on land-based agriculture, alternative sources such as waste streams, electrochemically produced carbohydrates, and other sustainable carbon sources are being explored.
Salts
Essential salts, referred to as macronutrients, like nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur are required for basic cellular functions and growth. Trace elements, referred to as micronutrients, such as iron, manganese, zinc, boron, copper, and molybdenum, are required for critical enzymatic activities.
Vitamins
Plant cells in culture may grow and proliferate faster upon addition of vitamins such as myo-inositol, nicotinic acid, pyridoxine, and thiamine.
Plant signaling molecules
Also known as plant hormones, phytohormones, or plant growth factors, are small molecules that control plant growth, development, and cell behaviour such as division, differentiation, and secondary metabolite production. Hundreds of different plant signaling molecules naturally occur in plants. The type and ratio of plant signaling molecules in the culture medium are critical for optimizing cell behavior and metabolite synthesis for production of the desired product.
Callus-derived Cell lines vs Stem Cell lines
Callus
A mass of induced undifferentiated plant cells. When a plant is injured such as due to cutting, pruning, or external damage, nearby cells dedifferentiate and form callus tissue at the wound site. The callus cells cover the wound and protect the exposed area from pathogens and further injury, and they regenerate damaged tissues by forming new cells and and new plant tissue like leaves, roots, or flowers. Callus can be grown as a semi-loose mass of cells on solid media and subsequently transferred to liquid suspension culture. Most microbotanical products are produced based on callus-derived suspension cultures.
Plant Stem Cells
Naturally occuring undifferentiated plant cells existing in meristems (growth zones) of plants. Cambial meristematic cells (CMCs) are plant stem cells isolated from shoots, roots or the vascular system and can be directly grown in liquid suspension culture upon isolation.