生物表面活性剂及Tween-80在一株菲降解菌降解过程中的作用研究

Numerous studies have been devoted to the physical-chemical weathering processes leading to the creation of unique soil formations having their own history that induce soil-biotic diversity. However, the extent to which unique geomorphic formations influence soil biotic seasonal variation is not clear. Our aim was to define seasonal variations of soil biota in soils of different-aged terraces of the Makhtesh Ramon anticline erosional cirque in southern Israel. The strong effect of Makhtesh Ramon (Ramon Crater) erosional fluvial terrace age initiated by climatic changes during the Late Pleistocene–Early Holocene period on seasonal variations in both soil properties and the abundance and composition of soil biota were demonstrated. However, age dependence was not constant and values for observed soil properties and microbial activity were negligible between younger and older terraces for certain seasons, while free-living nematodes along with bacteria-feeding group were strongly dependent on the geomorphic features of the ages throughout the study period.

Effects of a biosurfactant and a synthetic surfactant on phenanthrene degradation by a Sphingomonas strain

A novel phenanthrene (PHE)-degrading strain named as Sphingomonas sp. GF2B was isolated and identified from a farmland soil. Effects of a synthetic surfactant (Tween-80) and a rhamnolipid biosurfactant on PHE degradation by Sphingomonas sp. GF2B were investigated at different concentrations of the surfactants. The results showed that Sphingomonas sp. GF2B was able to mineralize up to 83.6% of PHE within 10 days without addition of surfactants. The addition of Tween-80 to the reaction medium inhibited greatly PHE biodegradation, with only 33.5% of PHE degraded. However, the biosurfactant facilitated PHE biodegradation, with up to 99.5% of PHE degraded. The preferential utilization of PHE as a carbon source and the enhanced solubility of PHE by the biosurfactant were likely responsible for the higher biodegradation efficiency of PHE in the presence of the biosurfactant. Therefore, it could be concluded that the application of the biosurfactant to PHE-contaminated soils was perhaps a feasible way to facilitate the PHE biodegradation.