1021-4437/05/5203- © 2005
Russian Journal of Plant Physiology, Vol. 52, No. 3, 2005, pp. 410–413. From Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 463–466.
Original English Text Copyright © 2005 by Pouneva.
Soluble humic substances (HS), which are natural
biologically active compounds, are of great importance
for plant growth processes in aquatic systems. It was
reported that in humic lakes the phytoplankton primary
productivity was higher . The inﬂuence of HS was
better expressed under unfavorable conditions of culti-
vation. It was reported that algal growth in the medium
containing HS was twice greater when the algae were
cultivated under unaerated conditions , at low pH
, at toxic concentrations of copper , and under
iron-limited conditions . It was shown that HS could
exert a direct inﬂuence on plant growth, affecting pho-
tosynthesis [5, 6] and activity of some enzymes .
The aim of the present work was to investigate the
inﬂuence of the patented substance Biomin, which con-
tain HS from soft coal, on the viability of algae during
long storage on agar medium. Its effects on the growth
of green algae cultivated in laboratory and outdoors in
suspension cultures, as well as on the protein, carbohy-
drate, lipid, and pigment content of algal cells were also
studied. The effect of HS on activities of
and glutamate dehydrogenase (GDH) associated with
the basal metabolism was studied as well.
MATERIALS AND METHODS
The experiments were carried out with suspension
and agar laboratory cultures of both green algae (
Meyen Tomaselli 8 and
C-3) and blue-green algae (
). Algae were cultivated in the
intensive suspension culture in cultivator described by
Dilov  on the nutrient medium of Georgiev
The algae were maintained in collection being culti-
vated on agar Bold basal medium and investigated
6 months after passage.
cultivated in semi-industrial ponds in Roupite. Shetlik
installations of 6 m
 during three different cycles
(24–30 July, 13–18 August, and 4–12 October), each
lasting 5 days, were used.
Biomin is a Bulgarian plant growth regulator elabo-
rated on the base of low-grade lignite coal. Humic acids
comprise 90% of organic matter. Biomin contained
61.2% C, 27.8% O, 5.4% H, 3.87% S, and 0.5% N. The
functional carboxyl and aromatic hydroxyl groups were
of 4.36 mg-equiv/g. Its ash content was 8.1%. Biomin
was added to the nutrient medium at ﬁnal concentra-
tions of 1, 10, 100, and 1000 mg/l. All concentrations
were calculated on the basis of active substances in the
The treatment of ponds in Roupite was made with
Biomin (1 and 10 mg/l).
The viability of algal cell cultures grown under stan-
dard conditions for 6 months on agar Bold basal
medium supplemented with 1 and 10 mg/l Biomin was
evaluated by using the 2,3,5-triphenyltetrazolium chlo-
Effect of Humic Substances
on the Growth of Microalgal Cultures
I. D. Pouneva
Institute of Plant Physiology, Bulgarian Academy of Sciences,
ul. Georgi Bonchev, Block 21, Soﬁa, 1113 Bulgaria;
fax: 359(2) 73-9952; e-mail: email@example.com
Received August 19, 2004
—Treatment with humic substances (preparation Biomin) considerably increased viability of algae
during long storage (6 months) in collection. The effect was greater with green algae (
) than with blue-green algae (
). In intensive cultures, lower Biomin concentrations
10 mg/l) increased the biomass production, protein, chlorophyll and carotenoid content, as well as
-esterase and glutamate dehydrogenase activities, whereas the lipid and carbohydrate content was higher at
100 mg/l Biomin. A high Biomin concentration (1 g/l) exerted an inhibition. Biomin supply to the cultures in
outdoor installation of Shetlik type was associated with a moderate stimulation of algal biomass accumulation.
It was concluded that Biomin might be helpful in the improvement of algal viability and growth.
Key words: algae - humic substances - viability - esterase - glutamate dehydrogenase - pigments - proteins - lipids
-esterase; GDH—glutamate dehydroge-
nase; HS—humic substance(s).
This article was submitted by the author in English.