Naslov
The accumulation and release of polysaccharides by planktonic cells and the subsequent bacterial response during a controlled experiment

Autori
Fajon, Céline ; Cauwet, Gustave ; Lebaron, Philippe ; Terzić, Senka ; Ahel, Marijan ; Malej, Alenka ; Mozetič, Patricija ; Turk, Valentina

Izvornik
FEMS microbiology ecology (0168-6496) 29 (1999), 4; 351-363

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
dissolved organic matter; polysaccharide; microcosm; nutrient; bacterial activity; excretion

Sažetak
Seawater from the northern Adriatic, with low phosphorus (0.03 microM) and nitrogen (0.01 microM NH_4) concentration, was incubated for 12 days in 20-l polycarbonate carboys. The addition of a nutrient mixture (0.6 microM PO_4, 5.1 microM NO_3, 1.8 microM NH_4, 10.6 microM SiO_2) induced a strong diatom bloom, reaching 25microg/l Chl a. Primary and bacterial production were stimulated by the initial enrichment of nitrogen and phosphorus but ceased when N and P depletion occurred after 4 days. Inorganic N exhaustion resulted in a significant production (and acculumation) of dissolved and particulate carbohydates. The initial accumulation of carbohydates (CHO) in the particulate phase was followed 2 days later by a signitificant release of dissolved CHO. The bacterial response to this organic carbon source, as reflected by glucosidase activity, was probably inhibited by the severe P limitation following the phytoplankton bloom. In the exponential phase, when P concentration was sufficiently high to sustain a significant glucosidase activity, no increase in either dissolved organic carbon or dissolved total CHO was observed. We hypothesise that the periodic accumulation of dissolved organic carbon in the northern Adriatic is due to an excessive nitrogen enrichment followed by a concurrent N and P limitation.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA