Phymckmitrry. Vol. 26, No. 4, pi. 885- 889. 1987. 0031~9422/%7 53.00 + 0.00 Printed in Great Britain. 0 1987 Pcrgamon Journal8 zyxwvutsrqponml Ltd. GROWTH AND PRODUCTION OF CELL CONSTITUENTS IN BATCH CULTURESOF BOTRYOCOCCUSSUDETZCUS RAFAEL VAZQUEZ-DUHALT and HUBERT GREPPIN Departement de Physiologie &g&ale, UniversitC de Genkve, 3, Place de I’UniversitC, 1211 Gentvc 4, Switzerland (Revised receiwd 23 My 1986) Key Word Idex-Botryococcus sudeticus; Botry ccocceae; lipid production; protein and carbohydrate contents; mass production rates. Abstract-The growth of, and the production of neutral lipids, carbohydrates and proteins by, the alga Botryococcus stufeticus in batch culture is described. The algal mass contains, during the stationary phase of growth, about 4.5 % protein, 7.5 % carbohydrate and 22.0 % neutral lipid on a dry weight basis. Some physiological characteristics of this species are discussed. INTRODUCTION The freshwater alga Botryococcus sudeticus is often confused with B. braunii [ 11. Indeed, the strain used in this study is classified under B. braunii species in the Cambridge collection. B. sudeticus (Cambridge strain of B. braunii) produces very small amounts of hydrocarbons [Z-S] in comparison to B. braunii strains [&lo]. This species is described by Lemmerman [lo] who noted that the cells accumulate oil. Chodat [ 1l] reexamined B. sudeticus and designated the alga as Botryosphaera sudetica in order to distinguish it from Botryococcus Ktitzing. Information on the physiological properties of B. sudeticus is lacking. In this study data concerning the development of this strain are presented, along with some physiological notes. RESULTS AND DISCUSSION Protein, carbohydrate and lipid contents during growth The pH of the medium increased during the first 2 weeks of the exponential phase of growth. When growth slowed down, the pH decreased and stabilized at about 8.1 (Fig. 1). The increase of pH can be linked to exponential growth because a new growth rate and new increase of pH were observed (data not shown) when the medium was replaced by fresh medium (pH 7.5) during the stationary phase. The dry weight (Fig. 1) and protein (Fig. 2) curves were of the expected type and fitted the Gompertz growth curve [ 123. Protein reached its maximal value at the fourth week and preceded increases in dry weight, which reached its maximal value after the tenth week. This dephasing in time could be due to the production of extracellular compounds, such as lipids and matrix compounds. In general, it is known that the generation time of colonial matrix algae cannot be estimated easily because, as in the case of B. sudeticus, the cells are embedded in mucilage, and the numbers of cells in the colonies are not homogeneous. Dry weight measurements thus include not only the weight of cells but also those of mucilage and lipids confined to the matrix. Therefore, neither the number of colonies nor the dry weight are necessarily correlated with the number of cells. During growth, B. sudeticus produced insigni&ant amounts of extracellular protein. Therefore, the total protein content could be used as a parameter for estimat- ing the generation time. In this work, we found an initial generation time of about 2.2 days (53 hr) on a dry weight basis and about 1 day (25 hr) on a protein basis. The kinetics of carbohydrate production did not fit a classic curve (Fig. 2) since it showed two phases. The first occurred between inoculation and week 4 (exponential Time heks) Fig 1. Kin&m of dry weight production of batch cultures of B. svdctlcwaodchangesinthcpHofthcmadiumrddrywdpht curve fitted the G0mpert.z growth curve [12]. where FV,is the initial weight (inoculate& p is the speci6e growth rate at t - 4 and s is a parameter that dmcrihea etnpi&ally the progr&va reduction in the specify growth rate which may he ascribed to B. 885