Long term effects of copper upon physiological processes and growth of Chlorella saccarophila (Kruger) Migula and Cyanidium caldarium Geitler

Estratto da « Giornale Botanico Italiano » Voi. 116, n. 3-4: 123-129, 1982

Long term effects of copper upon physiological processes and

growth of Chlorella saccharophila (Kriiger) Migula and

Cyanidium caldarium Geitler

G I O V A N N I A L I O T T A and A N T O N I O P O L L I O

Istituto Botanico dell'Università, Via Foria 223, Napoli

Accepted: 30 May 1983

A B S T R A C T . — It has been studied long term effects of copper upon physiological processes and growth of Chlorella saccharophila (Kriiger) Migula and Cyanidium caldarium Geitler, two algae which bave the optimum of p H at 6,3 and 1,5 re-spectively. The algae differed markedly in their resistance to the copper. Infact, growth of Chlorella saccharophila showed a lag time in presence of sublethal copper concentrations (0,25-1 mg/1). By contrast, Cyanidium caldarium was about 4000 fold more tolerant to the metal. I n both algae photosynthesis was more sensitive to applied copper than was respiration.

I N T R O D U C T I O N

Copper is essential to ali organisms as a constituent of many metallo-enzymes,

mostly those concerned with oxidation, but it is a poison when present i n excess

(BowEN, 1 9 6 6 ) . Since toxic effects may be seen at concentrations below 1 p p m i n

the nutrient solution, copper salts are widely used i n the control of microorganisms.

The mode of action of copper is not strictly specific and is stili the object of

discussion ( G A D D and G R I F F I T H S , 1 9 7 8 ; S A M U E L L S S O N and O Q U I S T , 1 9 8 0 ) .

Inhi-bition of many enzymes and physiological processes such as photosynthesis and

respi-ration bave been recognized mostly during experiments of short durespi-ration ( M C B R I E N

and H A S S A L , 1 9 6 7 ; O V E R N E L L , 1 9 7 5 ) . The present paper deals w i t h long term

effects of copper upon photosynthesis, respiration and growth of Chlorella

saccharo-phila (Kriiger) Migula and Cyanidium caldarium Geitler, two algae which bave

optimum growth rates at different p H ' s : 6 , 3 and 1,5 respectively. Moreover,

Cya-nidium caldarium Geitler lives i n acidic springs which often carry high levels of

heavy metals ( W H I T E et al, 1 9 6 3 ) .

— Velocità d i crescita d i Chlorella saccharophila e Cyanidium caldarium i n funzione del tempo alle concentrazioni d i rame riportate i n figura.

10 20 30 LO 50 hours

Fig. 2 — Chlorella saccharophila. Rates of photosynthesis (A) and respiration (B) i n the

medium as function of time at various level of added copper salt: O — O 0,5 mg/1; A — A 1 mg/1; • — • 2 mg/1. Ordinatesi rates in per cent of that i n Cu-free medium. — Chlorella saccharophila. Velocità d i fotosintesi (A) e respirazione (B) nel terreno d i

coltura i n funzione del tempo a varie concentrazioni di rame: O — O 0,5 mg/1; A — A 1 mg/1; • — • 2 mg/1. Ordinate: velocità espresse in per cento d i quelle ottenute

Fig. 3 — Cyanidium caldarium. Rates of photosynthesis (A) and respiration (B) i n the medium as function of time at various level of added copper sah: O — O 1 g/1; A — A 4 g / l ; • — • 16 g/1. Ordinates in per cent of that in Cu-free medium.

— Cyanidium caldarium. Velocità di fotosintesi (A) e respirazione (B) nel terreno d i coltura i n funzione del tempo a varie concentrazioni d i rame: O — O i g/I; A — A 4 g/I; • — • 16 g/1. Ordinate: velocità espresse in per cento di quelle ottenute nel terreno senza rame.

The photosynthesis rate of Cyanidium caldarium was affected only when

concen-tration of copper i n the medium reached 1 g/1, which was similar to the concenconcen-tration

of hydrogen ions. A t the same concentration of metal, the respiration rate was not

affected. Finally, Constant decline of both processes at higher levels of the metal was

observed. In the culture of Cyanidium without addition of copper, photosynthesis

and respiration rates were 172 and 26 nmoles 0 2 / m i n / l O ' ' cells respectively.

Table 1 shows the percentage of dead cells and copper sorption of Chlorella

saccharophila i n presence of various concentrations of copper i n the medium.

T A B L E 1

Dead cells copper sorption of Chlorella saccharophila after 48 hours of exposition

'to various concentrations of copper in the medium. The system contaìned IO' cells/ml.

Cellule morte e assorbimento del rame di Chlorella saccharophila dopo 48 ore di

esposizione a varie concentrazioni di rame nel mezzo di coltura. Il sistema conteneva

10^ cellule/mi.

Amount of copper ^ . , jj^ % copper applied - P f f i n the system --'--"^-j^^.^^. the

0,5 15 70 1 20 42 2 40 25 10 85 4

D I S C U S S I O N

A s other algae, Chlorella saccharophila (Kriiger) M i g u l a is able to re-establish a

normal growth rate i n the same medium if the concentration of copper added to the

medium is not too high. I n these conditions, the continuous decline of the rate of

photosynthesis observed i n our experiments seems due to the inhibition of the

photosynthetic process as well as to the dying of some cells (Fig. 1 and T a b . 1 ) .

This is consistent with the findings of several authors w h o bave demonstrated that

copper kills some but not ali of inoculum. Dead cells, absorbing copper more rapidly

then live ones, detoxify the medium ( S T E E M A N N N I E L S E N and W I U M A N D E R S E N , 1 9 7 0 ; A L B E R T A N O et al, 1 9 7 9 ) . A c c o r d i n g to M C B R I E N and H A S S A L ( 1 9 6 7 ) , the

respiration rate i n aerobic conditions is not as severely affected as photosynthesis by

^he same concentrations of copper i n the medium.

Noteworthy is the tolerance of Cyanidium caldarium Geitler to very high

con-centrations of copper i n the medium, i n spite of the fact that l o w p H increases the

availability of metal ions ( G A D D and G R I F F I T H S , 1 9 7 8 ) .

As matter of fact, p H can bave a considerable effect on both availability and

toxicity of heavy metals. W e are further investigating whether tolerance to heavy

metals is a general feature of acid-tolerant species.

R E F E R E N C E S

ABBOTT D . C . and P O L H I L L R . D . A . , 1 9 5 4 — The determinatton of copper in oils and fats by means of dihenzyl-dithiocarbamic acid and its salts. Analyst, 79: 5 4 7 - 5 5 0 .

ALBERTANO P . , FINTO G . and TADDEI R . , 1 9 7 9 — Evaluation of toxical effects of heavy metals to unicellular algae. 3 - Subtraction of the toxic element from the medium by the cells. Delpinoa, 21: 4 7 - 6 1 .

BowEN H . J . M . , 1 9 6 6 — Trace elemenls in biochemistry. Academic Press, N e w Y o r k .

EsTABROOK R . W . , 1 9 6 7 — Mitochondrial respiratory control and the polarographic measurement

of ADP: O ratios. I n : Methods in enzymology, 10: 4 1 - 4 7 . E d s . R . W . Estabrook and M . E . Pullman, Academic Press, N e w Y o r k .

GADD G . M . and G R I F F I T H S A . J . , 1 9 7 8 — Microorganisms and heavy metal toxicity. Microbial Ecol., 4: 3 0 3 - 3 1 7 .

M C B R I E N D . C . H . and H A S S A L K . A . , 1 9 6 7 — The effect of toxic doses of copper upon respiration, photosynthesis and growth of Chlorella vulgaris. Physiol. Plani., 2 0 ; 1 1 3 - 1 1 7 .

OVERNELL J . , 1 9 7 5 — The effect of some heavy metal ions on photosynthesis in a freshwater alga. Pesticide Biochem. Physiol., 5: 19-26.

SAMUELSSON G . and OQUIST G . , 1 9 8 0 — Effects of copper chloride on photosynthetic electron transport and chlorophyll-protein complexes of Spinacia oleracea. Plant Celi Physiol., 21 {}): 4 4 5 - 4 5 4 .

STEEMANN N I E L S E N E , and W I U M - A N D E R S E N S., 1 9 7 0 — Copper ions as poison in the sea and in freshwater. Marine Biology, 6: 9 3 - 9 7 .

W H I T E D . E . , H E M J . D . and WARING G . A . , 1 9 6 3 — Chemical composition of sub-surface waters. U.S. Geol. Surv. Prof. Paper, 4 4 0 - F .

R I A S S U N T O

Effetti a lungo termine del rame sui processi fisiologici e sull'accrescimento di Chlorella saccharophila (Kriiger) Migula e Cyanidium caldarium Geitler. - Sono stati studiati gli effetti a lungo termine del rame sui processi fisiologici e sull'accrescimento d i Chlorella saccharophila (Kriiger) Migula e Cyanidium caldarium Geitler, due alghe i l cui optimum d i crescita è a p H 6,3 e 1,5 rispettivamente. L e alghe differiscono notevolmente nella loro resistenza al rame. Infatti, concentrazioni subletali (0,25-1 mg/1) d i rame determinano una lag-fase nella crescita d i Chlorella saccharophila. Sono necessarie, invece, concentrazioni 4 0 0 0 volte maggiori del metallo per diminuire la crescita d i Cyanidium caldarium. I n entrambe le alghe la fotosintesi si è rivelata piià sensibile al rame della respirazione.