CONTROL OF COLONY AND UNICELL FORMATION IN A SYNCHRONIZED SCENEDESMUS(1) (2)

Area of Science:

• Microbiology
• Algology
• Cell Biology

Background:

• Scenedesmus exhibits pleomorphism, with colony formation being a key characteristic.
• Understanding the factors controlling Scenedesmus morphology is crucial for algal research and biotechnology.

Purpose of the Study:

• To investigate methods for controlling colony formation and unicell development in synchronized Scenedesmus cultures.
• To elucidate the role of specific chemical additives and culture conditions in modulating Scenedesmus morphology.

Main Methods:

• Utilized synchronized cultures of Scenedesmus under controlled light/dark cycles and rotation.
• Manipulated growth media by adding sodium citrate or EDTA to assess effects on colony formation.
• Employed daily transfers in soil-Bristol's medium to induce unicellular development.
• Observed cell division, release patterns, and spine development in various Scenedesmus strains.

Main Results:

• Addition of sodium citrate or EDTA to modified Bristol's medium prevented unicell formation, yielding only S. quadricauda-like or S. longispina-type colonies.
• Daily transfer to soil-Bristol's medium successfully induced a completely unicellular population within two days.
• Synchronized cultures exhibited two doublings per day, with cell division and release predominantly occurring during the dark period.
• No fixed pattern for daughter cell release was observed, and spines were fully formed at release, sometimes thickening with age.

Conclusions:

• Chemical additives like sodium citrate and EDTA can effectively control colony formation in synchronized Scenedesmus.
• Culture conditions, including medium composition and transfer frequency, significantly influence the transition between colonial and unicellular states.
• The study provides insights into the developmental plasticity of Scenedesmus, relevant for its study and application.