Modelling growth and histamine formation of Klebsiella aerogenes TI24 isolated from Indonesian pindang.

Indonesian salted-boiled fish (pindang) is a popular traditional food in Indonesia, which is made from Scombroid fish such as tuna and mackerel. As with other traditionally prepared fish products, pindang has important economic and social values, especially for those living in the coastal areas of Indonesia. However, pindang is a major cause of histamine fish poisoning (HFP) for consumers. Klebsiella aerogenes T124, a relatively high histamine-producing isolate from pindang, was used to describe lag time (λ), growth rate (µmax), maximum population density (Nmax), and histamine production in histidine broth and artificially contaminated Grey mackerel. Broth was adjusted to 1.5, 6, 10 and 20% w/v NaCl; mackerel was treated with 6% w/w NaCl, a level common to Indonesian industry practice, or not treated with additional NaCl. Samples were incubated at 10, 15, 20 and 30 °C. In broth, µmax and Nmax were significantly affected by temperature and NaCl, respectively, with λ influenced by both parameters. In control fish, µmax was significantly affected by temperature and NaCl, except at 10 and 15 °C; for 6% NaCl treatment, growth was only observed at 20 and 30 °C. Under similar incubation conditions for broth and fish, histamine formation was markedly affected by NaCl concentration. In broth, -5.1 to -6.6 log µg of histamine was produced per CFU, versus -4.6 to -6.6 log µg per CFU in fish. This study demonstrated that mackerel treated with 6% NaCl and stored at 10-15 °C prevents growth of K. aerogenes strain TI24 and formation of toxic levels of histamine.

Spatial distribution and seasonal variation of the trace hazardous element contamination in Jakarta Bay, Indonesia.

The Jakarta Bay Ecosystem is located in the vicinity of the megacity Jakarta, the capital city of Indonesia. Surrounding rivers and canals, carrying solid and fluid waste from households and several industrial areas, flow into the bay. Therefore, the levels of selected trace hazardous elements in water, surface sediments and animal tissues were determined. Samples were collected from two different seasons. The spatial distribution pattern of trace elements in sediment and water as well as the seasonal variation of the contamination were assessed. Quality assessment of sediment using the effects range median (ERM) showed that the concentrations of Hg, Cu and Cr at some stations exceeded the recommended values. Moreover, the concentrations of several trace hazardous elements in the sediments exceeded previously reported toxicity thresholds for benthic species.