Practical 3 : Batch culture of adopted microalgae

INTRODUCTION

Each group was given the different species of microalgae to be cultured. As mentioned in previous post, Tetraselmis was chosen by our group.

OBJECTIVES 

• To differentiate types of algal culture modes and their growth phases
• To differentiate the methods of microalgal growth measurement and harvesting

METHODOLOGY

1)      Prepare the algal medium in 1L flask

250 ml of F/2 or F/2+Si (depend on algae sample) was filled in 1 L flask & autoclaved. The appropriate volume of filtered sterilized vitamin was placed when the media has cooled down.

2)      Estimation of microalgal cell densities

A growing culture of microalgae was provided. A sample was pipetted carefully into the groove of the haemacytometer.The algal cell were counted under 400× (40× ocular) magnification.The no. of algal cells was counted. The counts in the quadrants were averaged and the algal density in the sample was calculated, taking into the account the dilution factor.

3)      Microalgae culture

o   Each medium was inoculate with enough volume of microalgae inoculums to achieve 1×10^5 starting cell densities.

o   Daily, once in the morning and once in the afternoon,the flasks were shaked gently to aerate and suspend the microalgae.

o   The microalgal cells in flask were counted daily. Photographs of the progress in colour development was took and described.

o   A graph was drawn to show the microalgae density trend and the various phases of development was determined.

      RESULTS AND DISCUSSION

              

Microalgal species	Day	Cell density (cell/ml)	SGR	Doubling time
Tetraselmis	0 (18/9)	426
	1 (19/9)	603
	2 (20/9)	700
	3 (21/9)	746
	4 (22/9)	685
	5 (23/9)	681
	6 (24/9)	687
	7 (25/9)	670
	8 (26/9)	557
	9 (27/9)	484
	10 (28/9)	358
	11 (29/9)	311

*Is there any differences between Tetraselmis and Chaetoceros? How about their use in aquaculture?

	Tetraselmis	Chaetoceros
Colour	Green	Brown
Shape	Cordiform and almost spherical	Elliptic cylinder
Organization	Unicellular	Simple colonies or chain of cells,
Live form & its distinctive feature	Flagellate	Non-flagellate
Class of microalgae	Chlorophyta	Bacillariophyta

Both species have been used in aquaculture for feeding of molluscs,penaied shrimp and marine fish.

CONCLUSION

Batch culture is the best way to practice in lab rather than continuos culture. It also can helps maintain their purity so that the growth phases interuption will be reduced.