BIOCHEMICAL CHARACTERIZATION AND PIGMENT PROFILE OF 6.pآ  The pigments are characteristic of certain

  • View

  • Download

Embed Size (px)

Text of BIOCHEMICAL CHARACTERIZATION AND PIGMENT PROFILE OF 6.pآ  The pigments are characteristic of...

  • Chapter 6





    6.1 Introduction

    The pigments are characteristic of certain algal groups. Four different kinds of pigments that are

    usually found in algae are chlorophyll, carotenes, xanthophylls and phycobilins but in Euglena is

    devoid of phycobilins pigments. Of the other three kinds, chlorophyll a, chlorophyll b, carotene,

    -carotene, zeaxanthin, flovoxanthin, flavicin are common pigment in Euglena.

    Chlorophyll and carotenes are fat soluble molecules and are extracted from thylakoid membranes

  • with the help of organic solvents such as acetone, methanol, etc. but phycobilins and peridinin

    are water soluble that can be extracted from algal tissues after the organic solvent extraction of

    chlorophyll from those tissues. In some cases, red colouration in the water occurs due to the

    increase in presence of characteristic xanthophyll pigment called astaxanthin or euglenorhodone

    or hematochrome. Cunningham and Schiff (1986a) found that Euglena contains xanthophyll

    pigments diadinoxanthin and diatoxanthin but lutein, fucoxanthin and violaxanthin are not

    present. Casper-Lindley and Bjorkman (1998) observed at high light intensities Euglena lacked

    xanthophylls pigment. The definition of photosynthetic pigments that cause light energy to turn

    into chemical energy in all photosynthetic organisms was first determined by Stokes (1864).

    Sorby (1873) classified blue chlorophyll as chlorophyll a, green chlorophyll as chlorophyll b and

    orange-yellow as xanthophyll according to the pigment colors. Chlorophyll is a key biochemical

    component in the molecular apparatus that is responsible for photosynthesis. Chlorophyll is a

    metal-chelate, or a central magnesium ion is bonded to a larger organic molecule called a

    porphyrin. The porphyrin molecule is composed tetrapyrrole units joined vinylic groups. The

    magnesium ion is the centre of electron transfer during photosynthesis (Fig. 6.1). The content of

    chlorophyll a relating to the pigment level is almost the same in all algal groups but chlorophyll

    b and c changes(Donkin, 1976; Martin et al., 1991; and Grung et al., 1992). Carotenoids are

    naturally occurring fat soluble pigments that are responsible for the different colours of algae

    (Ben-Amotz and Fishler, 1998). Carotenoids are usually yellow to red and present in green,

    yellow, leafy vegetables and in yellow fruits. They are aliphatic hydrocarbons consisting of

    polyisoprene backbone. Pigmentation in Euglenophyta is found to be due to the presence of

    carotenoids such as carotene, zeaxanthin, neoxanthin and diadinoxanthin (Goodwin, 1976; Kirk

    and Tilney-Bassett, 1978). Rosowski and Parker (1982) found the presence of zeaxanthin, lutein,

    violaxanthin and neoxanthin in euglenophyceae. Earlier it was found that secondary carotenoids

    such as ketocarotenoids of xanthophylls were associated with chlorophyceae (e.g., green algae),

    but then it had been encountered in euglenophyceae. The role of carotene pigments in algae is

    not exactly known but it is suggested that they function as a passive light protecting filter and

    have the role of accessory pigments transferring energy and oxygen (Lichtenthaller, 1987; Yong

    and Lee, 1991 and Bidigare et al., 1993). In Euglena, carotenoids are found to play a major role

    in protecting chloroplasts against photosensitized oxidation (Bamji and Krinsky, 1965). Vechetel

    et al., (1992) determined that carotene pigments are the most important photosynthetic pigments

  • and it prevents chlorophyll and thylakoloid membrane from the damage due to photo-oxidation.

    Carotenoids contain a conjugated double bond system of the polyene type (C-C=C-C=C). Energy

    absorbed by carotenoids are transferred to chlorophyll a for photosynthesis.

    Fig. 6.1: Molecular structure of chlorophyll

    Various studies have indicated that carotenoids may prevent or inhibit certain types of cancer,

    arthrosclerosis, age-related muscular degeneration and other diseases. At sufficiently high

    concentrations, carotenoids can protect lipids from peroxidative damage (Burton, 1984).

    Carotenoids have antiproliferative effect on various cancer cell lines; lycopene has been shown

    - Carotene has been

    shown to inhibit the expression of antiapoptotic protein Bcl-2 in cancer cells, thus reducing the

    growth of cancer cells (Karas, 2000). Paramylum is the characteristic carbohydrate reserve of the

    Euglenophyta (Braas and Stone, 1968) which is similar to starch. It accumulates when Euglena

    are grown on an organotrophic medium in the dark and is consumed either in the dark when cells

    receive or at the end of the exponential growth phase (Freyssinet et al., 1972) or when cells are

    transferred to the light (Dwyer and Smillie, 1970; Dwyer and Smillie, 1971; Freyssinet 1972;

    Schwartzbach et al.,1975). The chloroplasts found in Euglena contain chlorophyll which aid in

    the synthesis of carbohydrates is stored as starch granules and paramylon. In Euglena paramylon

    is made in the pyrenoids. The eugenoids have chlorophylls a and b and they store their

    photosynthate in an unusual form called paramylon starch, a B-1, 3 polymer of glucose. The

    paramylon is stored in rod like bodies throughout the cytoplasm. These are called paramylon

    bodies and are often visible as colorless or white rigid rods (Calvayrac, 1981). Protein or amino

    acids are the by-products of an algal process for the production of other fine chemicals, or with

  • appropriate genetic enhancement, microalgae could produce desirable amino acids in sufficiently

    high concentrations (Borowitzka, 1988). The high protein content of various algae species is one

    of the main reasons to consider them as an unconventional source of protein (Soletto et al.,

    2005). Euglena is an organism with a number of interesting characteristics. It has three, rather

    than two membranes surrounding its chloroplasts (Gibbs, 1978) which have implications for the

    targeting of nuclear-encoded chloroplast proteins. It is a popular flagellated laboratory

    microorganism found in freshwater environments (Buetow et al., 1982). It represents one of the

    simplest and earliest derived eukaryotic cells. The production of variety of extracellular

    substances plays an important role in growth, physiology and ecosystems of algae. Extracellular

    products which are liberated from Euglena contain lot of nitrogenous substances.

    Producer Product group Application

    Euglena ( - carotene) Carotenoids Pigments, cosmetics,


    Euglena gracilis Vitamin C and vitamin E Nutrition

    -tocopherol, ascorbic acid)

    Algal blooms are often disastrous in aquatic bodies and particularly in fish ponds due to the

    addition of fertilizers it causes eutrophication and alter the quality of water which results into

    fish mortality (Padmavathi, 2007). Most of the works deals with the physico-chemical

    parameters operating in a particular water body while some workers have discussed about the

    distribution of unicellular and colonial organisms. In 2000, Hosmani and Vasanth work on the

    biochemical aspects of water pollution in two lakes of Mysore city. Rahman et al., (2007)

    studied on Euglena bloom and its impact on fish growth. They correlated the water quality in the

    bloomed ponds with fish growth and found that bloom had a negative effect on fish growth.

    Though they did not analyze the gut contents of the fishes inhabiting the same ponds. Most

    researches on fish growth are based on impact of water quality on fish growth (Vas, 2006;

    Sugunan et al., 2006)

  • So far biochemical aspects of algae have received less attention in natural habitats of freshwater

    ecosystems (Gatenby et al., 2003). The present chapter embodies the results of investigation on

    the biochemical potential and pigment profile of Euglena tuba. Also included in this chapter

    some informations on intake of Euglena tuba by the indigenous fishes to explore its innate

    potential as fish feed.

    6.2 Methodology

    For the biochemical characterization and pigment profile analysis, all the 16 ponds were

    selected and algal samples were collected bimonthly from July-2009 to May- 2010. Euglena

    intake information was obtained by analyzing the guts of some indigenous fish variety.

    Informations pertaining to the fish kill was obtained by interaction with the local people through

    a structured questionnaire. The detail methodology pertaining to the work described in this

    chapter has already been discussed in Chapter 3.

    6.3 Results and Discussion

    6.3.1 Pigment profile of Euglena tuba

    Pigment concentration and biochemical properties are largely dependent upon the type of algae.

    Euglena that grows at different light intensities show remarkable changes in their chemical

    composition, pigment content and photosynthetic activity (Guschina and Harwood, 2005).

    Chlorophyll a, b and carotenoids are fat soluble pigment. Table 6.1 shows characteristics of



View more >