Biochemical responses of Camellia sinensis (L.) O. Kuntze to heavy metal stress.

Three heavy metals-mercury (II), copper (II) and nickel (II), each at a concentration of 10 and 100 micrograms/ml, were tested for their effects on various biochemical constituents of tea leaves. Both NI (II) and Hg (II) decreased the phenolic contents, while Cu (II) increased it to some extent. The metal treatments enhanced the activity of phenyl alanine ammonia lyase (PAL), while the activity of poly phenol oxidase (PPO) showed a decline. Heavy metal stress also decreased the chlorophyll content of the leaves, along with a significant reduction in Hill activity. Proline content increased significantly in all treatments.

Aerobic growth of motile and non-motile bacteria an the surface of solid culture medium in the presence of the heavy metal and ionic salts at two temperatures

Threshold concentrations of heavy metal and ionic salts defining the range of Concentrations, that do not suppress growth, were determined in tryptic soya agar medium. It has been found that the salts of NH4, Mg, Cd and Hg at low concentrations disrupt the symbiotic relationship between the solid surface culture medium and the microorganisms, but do not suppress the growth of the bacteria. These compounds have been included under two different groups as infection inhibitors [Cd and Hg] and as an infection stimulators [NH4, Mg and K]