Chronic toxic effect of Acenapthene on diverse microalgaes
Moreover, the present results are also in consonance
elaborated that changes in amino acid concentration may
with the deleterious effects of other fungicides on chl-a,
be due to synthesis from endogenous precursors or to
carotenoids and phycobiliproteins of marine microalgal
inhibition of normal catabolism.
communities investigated by Porsbring et al. (2009).
Phenols increased by 1.03±0.23 mg mlˉ²º of C. vulgaris,
Drastic reduction in carbohydrate content of C.
in presence of Acenapthene treatments. Similarly in D.
vulgaris and D. subspicatus was observed with rise in
subspicatus , shot up of phenol content to 1.07±0.01 mg
concentrations of the Acenapthene. Total carbohydrates
mlˉ²º and 0.45±0.02 mg mlˉ²º in Scytonema sp . after
of C. vulgaris diminished by 0.29 ± 0.011 , 0.23 ± 0.01,
16 days of PAH treatment (fig 2d). These findings also
and 0.20±0.05 mg mlˉ²º in Acenapthene treatments with
corroborated with the observations of Mallick et al.
doses of 1.25, 2.5 and 5 ppm of the end of 16 days (Fig.
(1994) who substantiated earlier that phenols could be
2a). Reduction by 0.25±0.01, 0.23±0.05 and 0.21±0.02
used as protectants to the organisms during stress or
mg mlˉ²º in D. subpicatus was registered in three different
drought conditions and further stated that this could be
applied doses at the end of 16 th day. Drop by 0.19±0.03
due to the possible conversion of primary metabolites
mg mlˉ²º at highest concentration of Acenapthene(10ppm)
into phenols.
was observed in Scytonema sp . Few studies endorsed that
PAHs adversely affects the carbohydrates in algae. Kumar
C/N Ratio
et al. (2008) quoted similar observations while studying
The C/N ratio increased slightly from 4.5±0.1 in
with Endosulfan induced biochemical changes in nitrogen-
the control C. Vulgaris culture to 5.14±0.15 in the
fixing cyanobacteria like Aulosira fertilissima, Anabaena
concentration of 1.25 ppm Acenapthene treated culture,
variabilis and Nostoc muscorum . Nirmal Kumar (1991)
and then encountered somewhat to reach 3.8±0.1 in
reported the inhibition of sugar contents of the algae
5 ppm PAH treated cells at the end of 16 th day. In D.
by increasing doses of substituted urea herbicide N,
subspicatus treated culture, the C/N ratio in control was
N-dimethyl N-(4-isopopylphenyl) urea and stated that the
5.1±0.14 while in PAHs treated cell maximum reduction
retardation might be due to the interference of chemicals
was 4.3±0.13 at the end of 16 th day. In Scytonema sp.,
during photosynthetic process, which ultimately lapse the
highest reduction was registered of 3.1±0.2 at the end
production of a net gain of carbohydrates.
of experimental day. The reduction of C/N ratio with
Acenapthene stress had a pronounced effect on the
increasing time and PAHs concentration may be due to
production of proteins in microalgae. The protein content
toxic effect of PAHs which has significantly damaged the
from all experimental flasks treated with Acenapthene
cells of alga . Carman et al. (1997) found that hydrocarbon
was lower than that of control (fig.2b). Even though
contamination enhanced nitrogen availability. Other
amount of protein in cultures treated with all three
investigators Burkhardt et al. (1999) and Riebesell et al.
doses, increased up to certain time but it did not exceed
(2000) demonstrated that the C/N ratio was influenced by
control values. However PAHs at higher concentration
a carbon enriched culture medium. In contrast, Chabbi et
(5 ppm) in C. vulgaris showed a maximum reduction of
al. (2004) considered that C/N ratios are a consequence
97% in the protein content after 16 th day. Protein levels
of the presence of decomposing plant and/or microbial
in D. subspicatus was 0.01 mg mlˉ²º upon Acenapthene
(including algae) residues.
treatments over 16 days. In Scytonema sp. protein content
completely diminished at the end of 16 days. Kapoor
Assimilating Enzymes
et al. (1996) also stated that the interruption of protein
Nitrate reductase (NR) was affected drastically in
synthesis could be due to the inhibition of enzymes and
presence of Acenapthene in two microalgal species. NR
structural proteins essential for growth of the organism.
activity of C. vulgaris , D. subspicatus and Scytonema
Time dependent inhibition of amino acids by Acenapthene
sp. declined by 97%, 91% and 93% in presence of
was recorded. Acenapthene reduced amino acid content
Acenapthene respectively when assayed after 16 days
by, 87%, 95% and 86% in C. vulgaris, D. subspicatus
(fig. 3a). Adikhary et al. (1984) studied the effect of
and Scytonema sp. respectively (fig 2c). Measures (1975)
carbamate insecticide Sevin on the growth, survival and
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