Accidental spills and the misuse of chemicals may lead to current and legacy environmental contamination and pose concerns over possible (eco)toxicological secondary effects and risks toward non-target microbes and higher eukaryotes, including humans, in ecosystems. In the last decades, scientists and regulators have faced requests to thoroughly screen, prioritize and predict the possible deleterious effects of the huge numbers of existing and emerging xenobiotics, wastewaters and environmental samples on biological systems. In this context, it has become necessary to develop and validate (eco)toxicity bioassays based on microorganisms (e.g., bacteria, microalga, yeast, filamentous fungi, protozoa) as test-organisms whose data should be meaningful for environmental (micro)organisms that may be exposed to contaminated environments. These generally simple, fast and cost-effective bioassays may be preliminary and complementary to the more complex and long-term whole-organism animal-based traditional ecotoxicity tests. With the goal of highlighting the potential offered by microbial-based bioassays as non-animal alternatives in (eco)toxicity testing, the present chapter provides an overview of the current state-of-the art in the development and use of microbial toxicity bioassays through the examination of relatively recent examples with a diverse range of toxicity endpoints. It goes into the (eco)toxicological relevance of these bioassays, ranging from the more traditional microalga- and bacterial-based assays already accepted at regulatory level and commercially available to the more innovative microbial transcriptional profiling and gene expression bioassays, including some examples of biosensors.

意外泄漏和化学品的滥用可能会导致当前和遗留的环境污染，并引发对生态系统中非目标微生物和高等真核生物（包括人类）可能的（生态）毒理学次生效应和风险的担忧。在过去的几十年里，科学家和监管机构面临着彻底筛选、优先考虑和预测大量现有和新出现的异生物质、废水和环境样本对生物系统可能产生的有害影响的要求。在这种情况下，有必要开发和验证基于微生物（例如，细菌、微藻、酵母、丝状真菌、原生动物）的（生态）毒性生物测定法，作为测试生物体，其数据应该对环境（微生物）生物体有意义可能会暴露在受污染的环境中。这些通常简单、快速且具有成本效益的生物测定可能是对更复杂和长期的基于全生物体动物的传统生态毒性测试的初步和补充。为了突出基于微生物的生物测定在（生态）毒性测试中作为非动物替代品的潜力，本章概述了微生物毒性生物测定的开发和使用的最新技术，通过检查具有不同毒性终点的相对较新的例子。它涉及这些生物测定的（生态）毒理学相关性，从更传统的基于微藻和细菌的测定已经在监管层面接受并商业化，到更具创新性的微生物转录谱和基因表达生物测定，