Abstract. Nonylphenol is a metabolic intermediate from the microbial transformation of detergents used worldwide. While nonylphenol shows some acute toxicity, it is also able to mimic important hormones resulting in the disruption of several processes by interfering with the signals that control the overall physiology of the organism. This work perform a critical reviews on the origin, environmental fate, microbial transformation, ecosystems impact and endocrine disruption capacity of nonylphenol. Due to mass production of parent products and potential toxicity, nonylphenol is an example of a microbial decay product that may pose an environmental risk. The analysis supports the need for better tests to evaluate, model and monitor the potential long-term environmental impact of single compounds produced as a result of an environmentallymediated degradation.

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The effect of a commercial emulsifier, sucrose ester, on the crystallization kinetics of hydrogenated sunflowerseed oil was studied by means of an optical method. Induction times were measured for hydrogenated oil with the addition of 0.01, 0.05, and 0.1 wt% sucrose ester. This emulsifier delayed nucleation, thus affecting the formation of critical nuclei and prolonging induction times. Kinetics of the [3' ---~13 polymorphic transition was followed by X-ray diffractometry. Addition of the emulsifier delayed the appearance of the signal at 4.6 t~. Moreover, longer times were needed to complete the transition. The kinetic model chosen to describe the transition process was based on the theory of Avrami. Avrami's exponent n was approximately 1 in all cases. The n value was in agreement with the fact that only one lY pattern was found. The I~ form could not be obtained directly from the melt, and it is unlikely that the I]'~ transition occurred through a melt-mediated mechanism. Transition was hindered by the rigidity of the sucrose ester structure. JAOC5 73, 321-326 (1996).

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Three seawater-based media were used for biomass and phycocyanin production by Arthrospira maxima. Among the three seawater-based media, growth rate and biomass were lowest in SWMAB, which is identical to SWM but includes several known essential elements (Zn, Cu, Mo, Mn). Growth in SWMX2, which has double the concentration of NaHCO 3 , N, P and FeEDTA than SWM, was not significantly different. Arthrospira maxima reached a biomass concentration of 2.7 ± 0.06 g L-1 in a mineral standard medium, but <1.2 ± 0.09 g L-1 in the seawater-based media. Pigment content in cells grown in the seawater-based media was <2.78 ± 0.46, <1.85 ± 0.18 and <19.83 ± 3.16 mg g-1 cell forchlorophyll a, carotenoids and phycocyanin, respectively. The phycocyanin produced in the seawater-based media had slightly different absorption and fluorescence maxima compared to those of A.platensis.