Question

2) Biofilms and other multicellular behaviors a) Recall that bacteria (and archaea) exhibit both transient and permanent multicellularity. How does these behaviors benefit bacteria? What are the costs? b) What kinds of environmentts seem to favor multicellular behaviors? Recall our discussion in the lecture – two that we discussed at length were mechanical antibiotic & chemical resistance and evasion of predators. c) Explain quorum sensing, especially the details we discussed with the Vibrio fischerii example. d) Compare and contrast incipient vs patterned multicellularity, and fit the examples of Bacillus subtillis, Myxococcus xanthus, and Streptomyces spp. into your explanation. How do these examples challenge our notions of the divide between single-celled and multicellular organisms? e) What is the microbiome? What are some of the implications for human health?

Answer 1

2a

Biofilms formed by microbes are dynamic structures having lot of advantages to the microbes. Bacteria survive on the surfaces by forming clumps or aggregates. In these aggregates, bacteria are connected to each other by polysaccharide fibers produced by the bacteria them selves. These aggregates along with the fibers provides protection from various biological and chemical agents. In these biofilms , the bacteria are separated by water channels. Through water channels , nutrients, wastes etc are circulated between bacteria. They function like a primitive multicellular organism and gives them the benefit of more survival capabilities.The bacterial biofilms are more resistant to antibiotics than free living bacteria.

Both gram positive and gram negative bacteria form biofilms. Biofilms cause lot of difficulty in controlling number of diseases. They perfectly adhere to the surgical instruments and spread the infections from one person to another. So the cost of these biofilms to disinfecting the bacteria using strong disinfectants especially in hospitals which will prevent spread of hospital born infections. Biofilms of bacteria are also very difficult to treat. So usage of more stronger antibiotics and for longer periods to contain infection is another cost to be paid because of the biofilms. In order to contain the disease, disruptng the biofilm is important. The matrix of the biofilm is degraded by biofilm disrupters. Then the bacteria need to be attacked. Certain enzymes such as nattokinase and lumbrokinase are used on surgical instruments to fight the biofilms.