Cultural conditions of arylsulfatase activity in Escherichia coli

Arylsulfatase activity and growth were estimated in Escherichia coli, isolated from marine sediment. Maximum activity was observed at pH 6.6 whereas the maximum growth was at pH 5.6. 2x10ˉ³ M is the optimum substrate concentration for the highest level of enzyme activity/synthesis as well as for its growth. In general higher substrate concentration tended to inhibit enzyme activity and also the growth of the bacterium. Maximum growth and highest enzyme activity occurred at 29°C and above this temperature decreased both of them. Besides these, glucose, sodium sulfate, sodium chloride, sodium dihydrogen phosphate, sodium acetate and ammonium chloride at higher concentrations were inhibiting the enzyme activity and growth. Above 0.2% of glucose, 3% of sodium chloride, 10x10ˉ³ M concentrations of sodium sulfate, sodium dihydrogen phosphate, sodium acetate and ammonium chloride inhibited the activity and growth also. These observations indicate that, to generalize a compound as inhibitor or activator it is difficult since this depends not only on its concentration but also on the source of the enzyme when more than one type is encountered in nature.

Studies on cultural conditions of marine Chromatium buderi Truper and Jannasch 1968

Photosynthetic characteristics of a purple sulfur bacterium, Chromatium buderi, cultured under different ranges of pH, temperature, light intensities and ammonium chloride concentrations were examined. Maximum bacteriochlorophyll a synthesis was observed at pH 6.5 whereas the optimum growth was at pH 8.0. In general, higher temperature tended to inhibit the chlorophyll a synthesis and growth. 30°C is the optimum temperature both for chlorophyll a synthesis and growth. At 25µE mˉ²Sˉ¹ the bacteriochlorophyll a content and growth attained maximum level. The response to this low light intensity is an adaptation that ensures a high photosynthetic rate for the purple sulfur bacterium that usually occurs in dimly lit environment. Besides these, ammonium chloride at low concentration enhances both chlorophyll a synthesis and growth. Above 0.5% of it causes the nitrogen-chlorosis and also retards the growth of the bacterium. Possible chemical and structural mechanisms involved are discussed.

The socio-economic and cultural structures of the fisherfolk communities

Fishing communities that have exploited the resource for generations constitute the main stakeholder groups in the fisheries of Lake Victoria. Several studies have examined Uganda's Lake Victoria fishing communities and characterised key stakeholders at community level over the last decade (SEDAWOG 1999a and b; Geheb 1997; FeSEP 1997; Kitakule 1991). The communities are made up of scattered settlements at the shores and on islands. The categories of people living in these communities include fishers who consist primarily of large numbers of male youths who provide labour to boat and gear owners. There are resident and non-resident fish traders who after securing their supplies at the beaches, depart for their market destinations. In addition, there are fish processors, mostly operating traditional and improved smoking kilns. Many other people, dealing in provisions and supplies also stay at the beaches, their activities depending on the level of fish catch. The fishing communities of Lake Victoria, Uganda, include auxiliary livelihood activities such as boat building, net repairing and transportation; bait supply and beachside kiosks, video halls and retail shop business. Other economic activities are brick making, charcoal burning/wood trade, farming and livestock keeping.