The surface and bottom waters samples were collected from six locations in Xiamen western sea. The quantified estimation of bacterial production (3H-thymidine method) and observation of bacterial hetemtmphic activity (14C-glucose method) have been made in order to have a better under-standing of the role of marine bacteria and their activities. The results showed that the mean value of bacterial hetemtmphic activity was 9

This paper deals with the application of lnirbiologieal parameters obtained by using AODC and SEM methods, and 3 H-thymidine ineoqoration into DNA nlethod tbr quantitative estimation of bacterial biomass, productivity anti growth doubling time in order to gaiJ better understanding of the role of marine bacteria and their activities in Xiamen western sea waters. The results showed that in the seawater surface, the mean valuv of total colifonus was 1.3

Polyphenol oxidase from Castanea henryi nuts was partially purified. Some characteristics of the enzyme were then determined to help devise measures for the prevention of undesirable enzymatic browning during storage and processing of the nuts. Preparation of acetone powder extracts of the nuts, ammonium sulfate precipitation, dialysis, and gel filtration resulted in 37-fold purification of the enzyme with a yield of 13%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the excitation spectrum confirmed the enzyme preparation to be homogeneous. The approximate molecular weight of the enzyme was determined by gel filtration to be 69 kD. The enzyme catalyzed the xidation of catechol and pyrogallic acid as substrates but did not affect cresol or tyrosine. Using catechol as substrate, pnitrophenol, thiourea, orcinol, and naphthol showed strong inhibition. The optimal pH and temperature for the enzyme were pH 5.0 and 40℃, respectively. The enzyme proved heat labile. When the enzyme was incubated at 70℃ for 30min, the remaining activity of the enzyme was only 8%. Possible approaches to applying the results of this study to the prevention of enzymatic browning in the production of C. henryi nuts is also discussed.

Organochlorine contaminants including 12 polychlorinated biphenyl (PCB) congeners and 18 insecticides were determined in water, pore water and sediments of the Jiulong River Estuary and Western Xiamen Sea, China. The results showed that the levels of the total PCBs ranged from non-detectable to 1500ngl-1 in water, from 209 to 3870ngl-1 in pore water, and from 2.78 to 14.8nggl-1 dry weight in sediments. Total organochlorine insecticide concentrations were from below the limit of detection to 2480ngl-1 in water, from 267 to 33400ngl-1 in pore water, and from 4.22 to 46.3nggl-1 dry weight in sediments. Concentrations of PCBs and insecticides in pore water were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. The PCB congeners with the highest concentrations were CB153, CB180 and CB194, which together accounted for 68-87% of total PCBs in water, pore water and sediment. Among the hexachlorocyclohexane (HCH) compounds, beta-HCH was found to be a major isomer. Analysis of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane (DDT) and its metabolites showed that 1,1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group. In comparison to a 1998 study in the Western Xiamen Sea, levels of organochlorines were enhanced due probably to recent inputs and changes in sediments.

The influence of specific phages on the population size of their host bacteria was studied using a model system of a selected phage and its host bacterium, identified as Aeromonas sp. Isolated from a lagoon in the southern Baltic Sea. For all initial phage/host ratios (PBR [phage/bacterium ratio] of 0.1 to 100), phage and host abundances reached a ratio of about 5 to 50 within the first 8h Interestingly, this range of phage/bacterium ratios of a single phage-host system corresponds to the ratio of virus to bacterial abundance found in natural habitats. The proportion of sensitive cells containing mature phage particles increased in the first 4h to 40%, and then decreased (at rates dependent on the initial ratio) within 12h (initial PBR of 100), 48 h (initial PBR of 10 and 1) and 72h (initial PBR of 0.1) to less than 1%. There was evidence for rapid development of immunity (probably pseudolysogeny), especially at high initial phage concentrations. After 96h incubation, carbon, nitrogen and phosphorus were added to improve the nutritional state of the bacteria. Although nutrients were added to all treatments when phage/host ratios were nearly equal, quite different reactions were observed for the bacteria populations with different initial PBRs. Those with low initial PBRs showed the most pronounced increase.