Abstract. Chromium (Cr) pollution in soils is a global concern that should be assessed. Pollution Induced Community Tolerance (PICT) methodology is a highly sensitive tool that can directly indicate metal toxicity in the microbial community. Ten soils with a wide range of properties were spiked with 31.25, 62.5, 125, 250, 500, 1000 and 2000 mg Cr·kg^-1, in addition to the control. Bacterial growth (using [³H]-leucine incorporation technique) was used to determine PICT, that is, whether bacterial communities developed tolerance in response to Cr additions to different soil types. Some bacterial communities did not grow normally at 1000 or 2000 mg Cr·kg^-1, probably due to high Cr toxicity, while others did. Regarding below 500 mg Cr·kg^-1, bacterial communities showed two responses depending on soil type: 7 of the 10 studied soils showed increased tolerance to Cr, while for the remaining 3 soils did not develop tolerance to Cr. Furthermore, the Cr level from which bacterial communities developed tolerance was dependent on the soil, i.e. Cr was more toxic in some of studied soils. The Cr effect on microbial communities was mainly determined by Dissolved Organic Carbon (DOC) and the fraction of Cr extracted with distilled water (H₂O-Cr) (R² = 95.6 %). Their effect on Cr in the soil might lead to an increase in toxicity (selection phase of PICT).

中文翻译：

---

增加细菌群落对 Cr 的耐受性以响应土壤特性和土壤中的 Cr 水平

摘要。土壤中的铬 (Cr) 污染是全球关注的问题，应该进行评估。污染诱导群落耐受性 (PICT) 方法是一种高度敏感的工具，可以直接指示微生物群落中的金属毒性。除了对照之外，十个具有广泛性质的土壤被掺入了 31.25、62.5、125、250、500、1000 和 2000 mg Cr·kg ^{-1 。}细菌生长（使用 [ ³ H]-亮氨酸掺入技术）用于确定 PICT，即细菌群落是否对不同土壤类型中添加 Cr 产生耐受性。^{一些细菌群落在 1000 或 2000 mg Cr·kg -1}时不能正常生长，可能是由于高 Cr 毒性，而其他细菌群落则可以。关于500 mg Cr·kg以下^-1，细菌群落根据土壤类型表现出两种反应：10 种研究土壤中有 7 种表现出对 Cr 的耐受性增加，而其余 3 种土壤未对 Cr 产生耐受性。此外，细菌群落产生耐受性的 Cr 水平取决于土壤，即 Cr 在一些研究土壤中毒性更大。Cr 对微生物群落的影响主要取决于溶解有机碳 (DOC) 和用蒸馏水提取的 Cr 分数 (H ₂ O-Cr) (R ² = 95.6 %)。它们对土壤中 Cr 的影响可能导致毒性增加（PICT 的选择阶段）。