The direct effect of ultrasound on the extraction of date syrup and its micro-organisms

In the date syrup industry, date fruits are mixed with a suitable amount of water at a temperature greater than 50 °C for about 1 h. This condition is not sufficient for killing the micro-organisms present in the fruit. In addition, Overheating for a long time can damages nutritious materials and also changes the final product's color. Ultrasound was applied for improving the quantity and quality of the extraction, and also to overcome the health problem. In this research, the following variables were examined: date fruit/water ratio, ultrasonic intensity and temperature. The results showed that sonication under the proper conditions can lead to a higher extraction in a shorter time with a better physical quality of the product. Most importantly, the sonication significantly decreased the microbial count in comparison to the classical method. This study also confirmed the presence of anti-microbial substances in date fruit, and that ultrasonic waves can accelerate their effects.     

Microplate-based microbial assay for risk assessment and (eco)toxic fingerprinting of chemicals

We have developed a multi-species microbial assay, MARA, for assessing the (eco)toxic risks of chemical compounds and for the determination of their toxic fingerprints. The main advantages with MARA are (1) the simultaneous testing on several microbial strains; (2) the concept of toxic fingerprinting; (3) the simple and inexpensive handling and reading of the test. The toxic activity is measured in parallel on 11 different micro-organisms lyophilised in a microplate. A concentration gradient of the chemical to be tested is added and growth is indicated through the reduction of tetrazolium red (TTC). The microplates are read by a common flatbed scanner or a microplate spectrophotometer. The array of the 11 different inhibition values constitute a toxic fingerprint, characteristic for each type of chemical compound, and it is shown that the assay can distinguish between 12 standard chemicals. Both the reproducibility (CV≈20%) and the sensitivity are similar to other toxicity tests based on micro-organisms.     

生化需氧量微生物传感器性能优化的研究

本文通过对几种微生物的筛选，找到活性较高的河流污泥微生物制成生化需氧量传感器，重点进行了培养基成分及测试条件等方面的优化，实验结果表明，电极对ＢＯＤ标准物质线性响应范围为１０－６０ｍｇ／Ｌ响应时间为１５ｍｉｎ，连续稳定地工作寿命在３０天以上，用于实际污水测定时，与ＢＯＤ５有良好的相关性。