Algal Culture : Scope and Methods SMG

A brief account of Algal culture

1. ALGAL CULTURE : SCOPE AND METHODS Dr. Saji Mariam George Associate Professor Assumption College Autonomous Changanacherry

2. ALGAL CULTURE : SCOPE & METHODS Farming of Algae. A form of Aquaculture SCOPE Algae can be grown in large quantity within a short period of time. In recent times, there is much interest in dietary supplements of algal origin and bio-fuels.   Algae can also be exploited for the commercial production of various products like dyes, fodder, bio-plastics etc.

3. Algae are commercially cultivated (cultured) for many purposes . i ) Algae as Food The total food production by marine algae is estimated to be eight times than that by land plants. The algae are rich source of proteins, fats, vitamins A, B, C and E ; omega -3 fatty acids etc. Several algae are edible. E.g. Ulva , Porphyra , Laminaria , Chlorella , Gracilaria , Gelidium etc. Many algal products are used in food industry. e.g Agar, Carageenan etc.

4. ii ) Algae as source of Dyes and Food colorants Phycoerythrin is a red pigment extracted from red algae. Porphyridium cruentum is the most commonly used species for Phycoerythrin production. Phycocyanin is a blue pigment derived from blue green algae. Spirulina platensis is the most popular algal source of this pigment. Phycocyanin is used as a food colorant in fermented milk products, milk shakes , ice creams, chewing gum, soft drinks, alcoholic drinks, desserts, cake decoration etc. Food colorants and dyes obtained from algae have nutritional value and are non-toxic.

5. iii ) Algae as Organic Fertilizers Algae , particularly brown and red algae can be used directly as organic fertilizers. Algae can be made into compost – the compost of Blue - Green Algae and Azolla ( Azolla - Anabaena symbiosis) – can be used in paddy fields to increase yield.

6. iv) Algal Bioplastics Alternative to the plastics Eco friendly Biodegradable A sustainable green initiative to combat plastic pollution. Images https://mymodernmet.com/ooho-edible-water-container/ http://eatinnovation.com/seaweed-bottles-drink-water/

7. v) Algae as a source of Pharmaceuticals Certain algae are rich sources of various bioactive compounds that have nutraceutical or therapeutic potentials and can be exploited in pharmaceutical industry.

8. vi) Algal Fuels Algae can be used for the production of making biodiesel, biobutanol , biogasoline , Methane, etc. e.g Dunaliella , Chlorella etc. An alternative to petroleum based fuels. vii) Algae as bioremediators Algae also has the potential to be used as bioremediators for Pollution Control. E.g Scenedesmus , Cladophora etc. have the capacity to remove heavy metals. viii) Algal cultures for research purposes Algal cultures are needed for research purposes. They can be used for morphological , physiological, cytological, genetical and ecological studies on algae.  

9. Types of Algal Culture Unialgal cultures - contain only one kind of alga, usually a clonal population (may contain bacteria, fungi or protozoa). Axenic cultures - contain only one alga (no bacteria, fungi or protozoa).

10. Culture conditions should resemble the alga’s natural environment as far as possible . Requirements: Water Carbon dioxide Minerals Light Temperature (15˚C - 35˚C. )

11. Culture (Cultivation) of Macroalgae Culture of macroalgae like Laminaria , Porphyra , Gracilaria , Ulva , Chondrus etc. Steps : 1. Collection 2. Isolation 3.Culture 4. Harvest

12. 1 . Collection Requirements: Suitable containers Chisel or small knife Forceps Gloves Mesh or cloth bag Ice-filled cooler Method : Wear gloves Mark containers with date, depth, location, whether the water is saline, brackish or fresh etc. Collect entire or a part of algal specimen from shallow or deep water. Large specimens should be shaken or gently squeezed on collection to remove excess water. Gently place the specimen in the container with sufficient water . Place the containers in an ice – filled cooler.

13. 2. Isolation Manual isolation Use of membrane filters for separation of filamentous algae from bacteria. Use of mixtures of ethanol (40–50%) and sodium hypochlorite (1%) for the removal of microepibionts . Antibiotic screening to eliminate fungal contaminants ( e.g. Nystatin 100mg/ml ).

14. 3 ) Culture (Cultivation) Methods : i )Fragment Culture Small fragments of algal thallus are placed in a suitable environment that will support their growth . Single Rope Floating Raft (SRFR) method (Long line cultivation or Line or rope farming or Monoline system) A long rope or Nylon twine of 10 mm diameter is attached to 2 wooden stakes with 2 synthetic fiber anchor cables and kept afloat with synthetic floats. The algal fragments are put in the twists of ropes or tied to Nylon twine and cultured in the sea shore area. The whole thallus can be harvested leaving a small piece that can be used for further cultivation. Used for cultivation of Gracilaria edulis , Gelidiella acerosa etc.

15. Single Rope Floating Raft (SRFR) method (Long line cultivation (Line or rope farming )

16. b)Use of Nets Nets are fixed to bamboo frames or wooden poles forming a raft like structure that is anchored to the sea bottom and held at a fixed depth with floats and can be used for algal culture.

17. c ) Pond culture A pond of 0.5 - 1.0 ha. with access to both salt and freshwater is needed so that the salinity can be adjusted and the water can be changed every 2-3 days. Water change is usually made using tidal flows, with gates to control the in flow and out flow of water. The pH of the pond water is important- slightly alkaline (pH 8) (e.g. Cultivation of Caulerpa , Gracilaria etc.) The pond should be drained to a depth of 0.3 meters. Plant the algal cuttings in the mud. After planting, flood the ponds slowly to a depth of about 0.5 to 0.8 m.

18. Pond used for  Gracilaria   cultivation http ://www.fao.org/

19. Harvesting of   Gracilaria   from Pond http://www.fao.org/

20. d ) In tanks (Tumble Culture) Translucent tanks of 0.6 to 0.9 m depths are needed . The algae that are tumbled in a tank by the upward water current generated by aeration are exposed to the surface light for a very brief period of time (10 seconds) and then immersed in to the bottom of the tank. Used for culture of Chondrus crispus , Palmaria palmata .

21. e) Seaweed cultivation at sea bottom   Place the seaweed into the sea bottom. Attach to sand-filled plastic tubes and place on a sandy bottom. Culture in the sea shore area.

22. f ) Green house culture A greenhouse with controlled environmental conditions can be used for algal culture Enhanced productivity. Reduction in contamination.

23. g) Spray culture Macro algae can be cultivated on land using saline or sea water under controlled environmental conditions of sunlight, temperature, moisture, nutrients etc. A water sprayer can be used on sand or in a multiple tier array to maintain a thin film of seawater enriched with nutrients on the surface of the macro alga and this can be recycled.

24. h) Tissue culture A part of the terminal portion of the thallus , 0.3 cm – 5.0 cm   or the blade or hold fast can be used as an explant . The explants can be cultured in enriched or artificial sea –water culture media containing growth regulators and this may result in callus formation and regeneration. e.g. Chondrus   crispus  , Laminaria angustata etc.  

25. Tissue culture of Macroalgae

26. ii)Reproductive Method Different kinds of spores like Zoospores, Monospores , Tetraspores , Carpospores etc. are collected and used for culture.

27. Cultivation of macro algae from spores

28. 4) Harvest Hand picking Use of Rotary cutters Nets Harvester Robotics

29. Culture of Microalgae Microalgae are very small, unicellular algae. The size ranges from a few micrometers to a few hundred micrometers. Include freshwater and marine forms. e.g. Green algae ( Chlamydomonas , Chlorella , Volvox ) Diatoms ( Pinnularia , Cyclotella , Navicula ) Blue green algae ( Nostoc , Oscillatoria ) Dinoflagellates ( Peridinium , Gonyaulax )     Steps Collection Isolation Culture Harvest

30. 1. Collection of Microalgae Water sample can be collected in small containers and put in an ice-filled cooler. Some algae form scums on the water surface . In such cases, scoop a small sample from the surface. Floating microalgae can be collected with mesh net. A deep water sampler can be used to collect water several meters below the surface. Images https://www.landcareresearch.co.nz https://askabiologist.asu.edu Alga collection using mesh net, Scooping Algal scum, Deep water sampler

31. 2. Isolation of Microalgae i ) Micropipette Method Microalgae can be separated from the samples using micropipette under microscope. Single cells can be isolated by micropipettes.

32. ii) Washing or Centrifugation Method Repeated washing or centrifuging the water samples results in the isolation of larger organisms. Image https://www.youtube.com/watch?v=0SgqFjpsSOY   Algae Centrifuge

33. iii) By exploiting the phototactic movement By this method the motile algae will move to one direction and can be isolated with a micro pipette. iv ) Serial dilution Agarplate method A unialgal culture may grow in one of the higher dilution tubes. Figure - uploaded by  Dr.- Ing Samuel Kofi Tulashie

34. Required algal species can be picked up with an inoculation needle under a microscope and then can be streaked on the surface of agar plates and incubate under suitable conditions of light and temperature. The developed algal colonies can be transferred to culture tubes for obtaining pure culture. Figure uploaded by  Nutan Prasad Rout

35. 3. Culture of Microalgae Microalgae can be cultured in photobioreactors (fiberglass tubes, plastic bags , flat-panels etc.) or in round shallow tanks. Images: http://solar-components.com/ https://news.algaeworld.org/2017/08 https://phys.org/news/2012-11-

36. Culture media for algal culture Culture medium or nutrient medium is an artificial or synthetic medium in which algae can be grown. Bold's Basal medium (BBM – Medium) with vitamins This is a freshwater algae medium without the need for soil-extract or vitamins . BBM is used to grow a variety of green algal cultures. e.g.  For culture of   Chlorella, Chlorococcum etc.

37. 2. Modified Chu No. 10 medium Widely used for both prokaryotic and eukaryotic algae e.g. Blue green algae, diatoms, green algae 3. Chu 13 Medium CHU 13 contains essential minerals  and trace elements that are required by algae for growth, but with no carbon source and hence this medium is suitable only for the growth of phototrophs . It is used as a growth medium for the alga Botryococcus braunii .

38. 4. Miquel's solution This medium is suitable for freshwater diatoms . 5. F/2 medium The most common and widely used general enriched seawater medium for growing marine algae, especially diatoms . 6 . Walne's medium Used for the cultivation of marine microalgae. 7 . Schreiber's solution Used for culture of diatoms. 8. TMRL medium Used for culture of microalgae.

39. HARVESTING OF MICROALGAE Harvesting should not cause contamination of the biomass or influence biomass quality. Harvesting of microalgae can be done by various methods such as Coagulation and flocculation Flotation Centrifugation  Sedimentation Filtration or a combination of various techniques.

40. Coagulation and Flocculation https://doi.org/10.1016/j.biortech.2015.06.097 The coagulation-flocculation processes using coagulant (FeCl 3 ·6H 2 O), various flocculants based on polyacrylamide , polyethylenoxide facilitate the removal of suspended and colloidal particles and concentrate the algae suspension. Flocculation allows for effective removal of algae from large amounts of liquid media. The microalgal biomass (0.05%, w/w) needs to be concentrated to a paste with 15% – 25% water content. 

41. Flotation https://doi.org/10.1016/j.biombioe.2018.11.018 Dispersed air floatation and dissolved air flotation can be applied in microalgae harvesting and dewatering.

42. Centrifugation Centrifugation as a secondary dewatering step will reduce the time and costs associated with dewatering.

43. Sedimentation Tanks are cylindrical with a funnel shaped bottom so that the settled microalgae are concentrated near the outlet. The outlet is placed at the bottom of the tank so that the collection of the settled microalgae can easily be recovered.

44. Filtration Filtration techniques can concentrate microalgae cells in the suspension upto 5-18%   . Vacuum filtration harvesting technique is most suited for large microalgae cells (greater than 10 μm ).

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