Ammonium compounds can affect gram-negative bacteria, contrary to the misconception. Gram-negative bacteria have an outer membrane that serves as an additional barrier to protect the cell from external substances. However, ammonium compounds can still penetrate this outer membrane and exert their effects on the bacteria.

Ammonium compounds can affect gram-negative bacteria in a variety of ways. For example, they can interfere with the proton motive force, which is essential for energy production in the bacteria. They can also damage the cell membrane and inhibit the synthesis of essential molecules, such as proteins and nucleic acids.

The specific effects of ammonium compounds on gram-negative bacteria can vary depending on the type of ammonium compound and the concentration used. Some ammonium compounds may be more effective than others at inhibiting the growth of gram-negative bacteria.

In conclusion, ammonium compounds can affect gram-negative bacteria, although they may be less effective than against gram-positive bacteria due to the presence of the outer membrane.