How does bokashi work: the science

Anaerobic versus aerobic

A traditional compost pile is broken down aerobically by microbes, bugs and fungi. As the process is aerobic, it is important to keep turning the materials regularly. This allows enough oxygen to get to the aerobic microbes. Should the process turn anaerobic (i.e., the pile is starved of oxygen) then it will start to putrefy and smell awful.

The bokashi bacteria, however, thrive in anaerobic conditions. By fermenting food in anaerobic conditions we allow the bokashi microbes to take over and suppress the nasty putrefying bacteria. No putrefying bacteria, no rotting smell, or harmful off-gassing.

Bokashi EM (effective microorganisms)

Bokashi bran

EM (effective microorganisms) are a selected group of microbes that work together beneficially to ferment food waste. The original EM product (EM1) was developed by a Japanese researcher (Teruo Higa) in the 1980’s. By carefully selecting a mix of bacteria, Higa was able to develop a group of beneficial bacteria that are universally applicable. These microbes are able to survive (and thrive) in a wide range of real world conditions.

Today, there are different varieties of EM1-type products available. Whilst the exact microbes and the relative quantities of each may vary from product to product, the majority of bacteria in the EM culture fall into the following three categories:

Lactic acid bacteria (LAM)

These bacteria convert sugar into lactic acid. This lactic acid production reduces the pH and produces an environment that is unfavorable for pathogens and methane-producing bacteria. Without this group of bacteria there would be no fermentation.


Yeasts are single-cell fungi. Yeasts help to decompose sugars and create many beneficial by-products such as vitamins, hormones and amino acids.

Purple non-sulfur bacteria (PNSB)

PNSB microbes are able to survive in a wide variety of environments and this adaptability makes them a very useful group within any EM product. Their main benefit is in breaking down hydrogen sulphide gas and ammonia and reducing the odors associated with these gases.

Order now! Find all your bokashi composting supplies in our online shop.

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Bokashi composting: how to get started

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