QIU+Chen

【Abstract】Microalgae as an important marine resources， rich in high content of polysaccharide， protein， fatty acids. The fatty acid content of microalgae is high， and its propagation speed is faster than herbaceous plants. It also has a high use value. The experiment tried on the basis of the screening of high yield oil microalgae， add different commonly used plant hormone， using growth monitoring， analysis of product components. Select several plant hormones to improve microalgae products production， provides guidance on the deep research and commercial production.

【Key words】Microalgae； Fatty Acid； Plant Hormones

0 Introduction

Microalgae is a kind of rich nutrition and high photosynthetic utilization of autotrophic plants， they are widely distributed in the land and sea. Because of its shape can be observed under a microscope， so called microalgae. Microalgae has the characteristics of rapid propagation， so the production of organic resources is much higher than most of terrestrial plants and other aquatic plants. In recent years， researchers have based on the research of the microalgae got many new way of synthetic organic product. But the study of microalgae is still in the exploratory stage， how to make use of microalgae for efficient production became a difficult problem in the field of study.

There are many types of microalgae， the main products include proteins， polysaccharides， fatty acids， pigment， etc. Among them， the fatty acid has important functions in the body， so the microalgae in the production of fatty acid research has become the current hot research direction.[1] Fatty acid is the simplest kind of fat， it is a lot more complex grease composition. Polyunsaturated fatty acids are the active ingredient in the brain， human beings are unable to synthesize it， need to get them through the plants. The researchers found terrestrial plants need longer growth cycle， unable to effectively improve fatty acid production. The discovery of micro algae will solve the problem.

In life， human beings use large amounts of additives. Using additive to improve the quality and quantity. Including natural and artificial additives. In the field of plant， plant quality is a common additive， widely used in agriculture.[2] In‘The World Pesticide-Plant Growth Regulator， there are hundreds of plant hormones， the author compared the stability， toxic and practicability of these hormones， screening the hormone which can help plants grow， to improve the product yield of additives.[3]

1 Methods

The algae strains of experiment are high oil content. Using BG-11 culture medium for culture. After the OD value is greater than 6， doing centrifugal collection and suspension with fresh culture medium. And then go to packing. Experiment selected 6 - Benzyl Amino Purine（BAP）， Brassinolide（BR）， Gibberellic Acid（GA）， Naphthalene Acetic Acid（NAA）. The four kinds of plant hormones are widely used and reasonable price without toxicity.

According to previous literature reports， each additive are grouped according to the concentration gradient whit parallel groups under 24 h illumination， 23℃ constant temperature and ventilation cultivation. The samples are regular gotten every day. Then centrifugal drying biomass measurement， measuring oil content， gas chromatographic detection of fatty acids composition.

2 Results and discussion

Experiment found that four kinds of plant hormones were not inhibit the growth of microalgae. In the two groups including 6-Benzyl Amino Purine（BAP） and Gibberellic Acid（GA）， biomass， oil content and fatty acid composition of experimental group were found no apparent change with control group. According to this experiment， these two kinds of plant hormones is no role for microalgae. In the experimental group of Brassinolide（BR）， percentage of oil and fatty acid composition has no change. But their biomass is higher than the control group. Relative to the high prices of Brassinolide（BR）， the increase benefit of biomass is not practical. Trials found that on the premise of guarantee the oil content and fatty acid production， Naphthalene Acetic Acid（NAA） can effectively improve the micro algae biomass， after adding the Naphthalene Acetic Acid（NAA）， the experimental group of biomass has been higher than the control group， and its growth rate is faster.

Studies showed that Naphthalene Acetic Acid（NAA） as common agricultural additives can be used for the cultivation of microalgae. It is harmless， price moderate. It can be used to accelerate the breeding of microalgae， make microalgae biomass to environment saturation quickly， end logarithmic phase early and get into organic matter accumulation phase. The effect of additive to other microalgae has not been texted， but if it can also have the same effect for other micro algae， it can be used in commercial mass production with great improvement in the industry efficiency and production.

【References】

[1]Borowitzka， M.A.， Moheimani， N.R.， 2013. Algae for Biofuels and Energy[M]. Springer， Dordrecht， New York.

[2]Hunt， R.W.， Chinnasamy， S.， Das， K.C.， 2011. The effect of naphthalene acetic acid on biomass productivity and chlorophyll content of green algae， coccolithophore， diatom， and cyanobacterium cultures[J].Appl. Biochem. Biotechnol.164，1350-1365.

[3]Park， W.K.， Yoo， G.， Moon， M.， Kim， C.W.， Choi， Y.E.， Yang， J.W.， 2013. Phytohormone supplementation significantly increases growth of Chlamydomonas reinhardtii cultivated for biodiesel production[J].Appl. Biochem. Biotechnol.171，1128-1142.

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