Biofilm/capsular material produced by the soil bacteria is detected by
The principle of microbial physiology explains that growth regulation and host interactions follow molecular programs. Hence Congo red fits best because it corresponds to prokaryotic strategies, as documented in authoritative sources on microbiology.
Ref: Madigan et al., Brock Biology of Microorganisms, 15th Edition, Chapter 13, Virology, explains viral replication and virus-host interactions detailing microbial genetics.
