Visando elucidar alguns aspectos do metabolismo respiratório de raízes inundadas de espécies arbóreas tropicais tolerantes (L. muehlbergianus, S.commersoniana e S. virgata) e intolerantes (P. dubium e S. terebinthifolius), plantas foram submetidas a 2, 10 e 60 dias de alagamento. Após estes períodos, determinou-se a absorção de O2 e liberação de CO2 pelas raízes. O metabolismo respiratório das raízes de espécies tolerantes apresentou uma queda com o alagamento. Somente S. commersoniana apresentou uma recuperação da respiração após 60 dias de inundação. A espécie intolerante S. terebinthifolius não teve seu metabolismo aeróbico afetado pelo alagamento, enquanto que P. dubium, também intolerante, apresentou queda na absorção de O2 com dois dias de hipoxia e recuperação após 60 dias. A liberação de CO2 nas espécies tolerantes seguiu o mesmo padrão da absorção de O2, com exceção de S. commersoniana, que teve uma redução na liberação de CO2 após 60 dias de inundação semelhante ao ocorrido com P. dubium. Em S. terebinthifolius não houve redução significativa com o alagamento. A dificuldade de se estabelecer diferenças no metabolismo respiratório das espécies estudadas, quanto a tolerância a inundação, ressalta a complexidade de respostas das plantas tropicais.
Aiming at elucidating certain aspects of the respiratory metabolism of roots of flood-tolerant tropical tree species (Lonchocarpus muehlbergianus, Sebastiania commersoniana and Sesbania virgata) as well as flood-intolerant species (Peltophorum dubium and Schinus terebinthifolius), plants were submitted to 2, 10 and 60 days of flooding. After these periods, the absorption of O2 and liberation of CO2 by the roots were determined. The respiratory metabolism of the roots of tolerant species presented a drop due to flooding. Only S. commersoniana presented a recovery in respiration after 60 days of flooding. The intolerant species S. terebinthifolius did not present alterations caused by flooding in its aerobic metabolism, whereas P. dubium, also intolerant, presented a drop in the absortion of O2 with two days of hypoxia, and recovery after 60 days. The liberation of CO2 in the tolerant species followed the same pattern of O2 absorption, with the exception of S. commersoniana, which presented a reduction in the liberation of CO2 after 60 days of flooding similar to what happened to P. dubium. In S. terebinthifolius there was no significant reduction with flooding. The difficulty in establishing a difference pattern in the respiratory metabolism of the species studied, concerning tolerance to flooding, emphasizes the complexity of tropical plant responses

Fermentation kinetic, thermokinetic and morphological investigations of biological carbonsource conversions into microbial biomass and other reaction products can be used for improving the efficiency of biotechnical processes. In this way biorhythmic processes on a macroscopic scale could be found in transitional stages of microorganism cultivation. These biorhythmic processes can be explained by the occurence of different cell states in the cell cycle. I n order to characterize these cell states synchronized microorganism growth was investigated with the aid of the phased culture method. Two states could be observed in the case of yeast growth: the single ccll state and the budding cell state. The duration and efficiency of the single cell state is dependent on the growth limitation and the carbon substrate feeding. Thus the reduction of carbon substrate feeding in states of synchronized populations which are characterized by a high percentage of single cells and by energy metabolite production which, in turn, is influenced by carbon substrate concentration can cause increased material and energetic efficiencies of biological carbon-source conversions.

The influence of perturbations on continuous yeast cell cultivations on hydrocarbons of crude oil is described.Due to such perturbations the fermentation system leaves its steady state, passes through transitional stages and reaches a new steady state. In the transitional stages a damped oscillation of biomass concentration, percentage of budding cells, oxygen consumption rate, and heat flow is observed. These results can be explained by partial synchronization of yeast cell functions in microorganism populations. I n phases of partial synchronization the cell cycle of a single cell is reflected by the behaviour of the microorganism population. The adaptationof the carbon substrate feeding rate to the state of partially synchronized microorganism population makes possible lower specific substrate consumption in biomass production.

The experimental technique for measurement of microbial culture heat evolution directly in fermenter has been described and its correctness analysed. Heat-to-oxygen ratio, Qo, of synchronized yeast culture in the absence of fermentative metabolism has been found to be practically independent of a cell cycle phase and close to the theoretical constant predicted by the mass-energy balance theory. The collection of literature data on the heat-to-oxygen ratio is given. Energetic properties of cell biomass are discussed on the bask of the obtained and the surveyed values of Q0.