Search some sponges in rivers, lakes or in the ocean, or craft them if you don't want to search! Then craft some Must, place it under water, and let it grow. If the Must is grown (lighter green), you can harvest it! If the must is not fully grown, it will just drop the Must block. If it is grown you get some Bunch of Bacteria. Then craft some bacteria colonies!
Bacteria:
Bacteria can be "tamed" to eat a special type of block like dirt, stone, water, lava, etc. You just have to place a bacterium colony, place all types of blocks you want it to eat directly above it (grass and dirt are the same, you don't have to place both) and finally power it by redstone or just place a redstone torch/block next to it! You will see it spread! (All spreading Bacteria blocks are of one colony!)
Replacer:
Will automatically set the block type below as food and will replace it with the block type above!
To start, just power it with redstone!
Jammer (item):
The Jammer item is a remote control which sends a jamming signal to ALL bacteria colonies in the world!
Jammer (block):
You can place a Jammer wherever you want the bacteria to stop. If the Bacteria reaches it, all Bacteria blocks of that colony will die! (Other colonies will continue to spread)
Bacterium Splash Potion:
Throw the splash potion and the bacteria will infect the block it hits.
Isolation (Bricks by default):
Build a rectangle/square/circle/whatever horizontally on the ground and place bacteria in the middle! They won't eat below it so they won't grow out of the area you defined!
All mods in the list blow are available in the Minecraft Modinstaller (click here)... Alternatively we offer you mods here as a ZIP File you can install manually:
Minecraft
Rating
Requires
Download
1.8 Forge
none
1.7.10 Forge
none
1.7.2 Forge
none
1.6.4 Forge
none
5
Installation Instructions (without Modinstaller)
Forge Mods
Open the new launcher and make sure the version of Minecraft the mod requires is already installed.