Untersuchungen zur lichtabhängigen Nitritreduktion von Chlorella
Summary1.The dependence of nitrite reduction activity in Chlorella fuscaShihira et Krauss, as measured by uptake of nitrite, on the developmental stage, light intensity and CO2 concentration was investigated.2.There is a quantitative relation between uptake of nitrite-nitrogen and increase of organic cell-nitrogen.3.The kinetics of nitrite reduction in light are linear with time at high CO2 concentrations (3% in air) but biphasic at low CO2 concentrations (0 to 0.03%). In the steady state phase nitrite uptake is stimulated by an increase in the CO2 concentration from 0 to 0.03%. The initial phase and the steady state phase exhibit a different temperature dependence.4.Nitrite uptake in the steady state phase is completely inhibited by iodoacetamide at concentrations which inhibit the photosynthetic CO2 reduction (5×10−5 M). At lower iodoacetamide concentrations (1 to 2×10−5 M) the linear time course of nitrite uptake at high CO2 concentrations is changed in the same manner as it is when the CO2 concentration is lowered.It is concluded that under special conditions (e.g. low CO2 concentration) the rate of steady state nitrite reduction in light is limited by the supply of carbon skeleton (i.e. N acceptors in the synthesis of organic nitrogen compounds) from the photosynthetic CO2 reduction cycle.5.Pre-illumination in the presence of nitrite followed by a dark period depresses the initial phase of nitrite uptake in light at low CO2 concentrations. Pretreatment with nitrite in the dark lowers the nitrite uptake of the cells in the initial phase by exactly the same amount of nitrite which has been taken up during the pre-darkening period.
 It is concluded that there is a correlation between the initial phase of nitrite reduction in light and the respiration-linked nitrite reduction in the dark.
Zur Photosynthese synchron kultivierterChlorella pyrenoidosa
ZusammenfassungDie in der Zellentwicklung vonChlorella pyrenoidosa auftretenden Schwankungen im CO2-Gaswechsel zeigen bei sofortiger Messung der photosynthetischen Leistung an Algensedimenten eine Differenz zwischen dem Maximum in der Lichtphase und dem Minimum in der Dunkelphase im Verhältnis von 6∶1. Diese Differenz vergrößert sich bei wiederholter Messung der Photosynthese am gleichen Sediment durch den bei Jungzellen in der ersten Hälfte der Entwicklungsperiode erfolgten starken Photosyntheseanstieg um ein Vielfaches, da die niedrige Photosyntheseleistung der Autosporenmutterzellen in diesem Entwicklungszustand unverändert bleibt.Die beschriebene Methodik ermöglicht es, den Entwicklungszustand der Jungzellen längere Zeit festzuhalten und somit die Abhängigkeit der Photosyntheseschwankungen vom Entwicklungszustand der Algen aufzuzeigen. Diese Schwankungen der Starklichtphotosynthese werden im Zusammenhang mit den beobachteten Fluorescenzänderungen diskutiert.
Organic geochemical characteristics and depositional setting of Tertiary organic-rich sediments from onshore Penyu Basin , eastern Chenor , Pahang , Malaysia
Poor knowledge of the organic facies characteristics of the eastern Chenor Pahang has made it remain an untapped potential in the Penyu Basin. Therefore, detailed geochemical and petrographic characterization of the Tertiary organic facies of the eastern Chenor area of the Penyu Basin was carried out to characterized its organic matter (OM) source input. Towards achieving the goal, this study focuses on determination of organic matters richness, type and origin as related to their paleoenvironmental conditions of the carbonaceous mudstone and shale using organic petrography combined with organic and inorganic geochemistry. The sedimentary succession is characterized by fine to coarse grained sandstone occurring in association with carbonaceous mudstone and shale in a predominantly fining upward sequence within a lacustrine environment. These facies are generally enriched in organic matter as indicated by the TOC results, hydrocarbon yield (S2) and extractible organic matter (EOM), suggesting significant hydrocarbon generation potential for the area.