substrate sludge

例句：

1. 1. The growth of microbes is greatly influenced by the quality and composition of the substrate.
   微生物的生长很大程度上受到底物质量和组成的影响。
2. 2. The experiment was designed to test the effect of different substrates on plant growth.
   这个实验旨在测试不同底物对植物生长的影响。
3. 3.The researchers found that the type of substrate had a significant impact on the rate of decomposition.
   研究人员发现，底物的类型对分解速率有显著影响。