BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 21. BIOTECHNOLOGY OF PROTEIN PRODUCTION

21.5. PRODUCTION OF MICROBIAL PROTEIN FROM NATURAL GAS (METHANE)

Natural gas as a raw material for microbial protein production has also lost its Prospects due to limited resources and high prices on the global market.

Research conducted in the 1960s and 1970s made it possible to isolate pure cultures of microorganisms capable of efficiently converting the methane in natural gas into protein. These are methane-oxidizing Bacteria, primarily Methylococcus capsulatus, which belongs to obligate methylotrophic microorganisms.

The Specificity of cultivating methane-oxidizing bacteria on natural gas lies in the fact that the main nutrients are gases (methane and oxygen), which must be supplied in sufficient quantities to The Cell walls, while the optimal methane concentration depends on the methane-to-air or methane-to-oxygen ratio. It has been established that the bacteria's demand for oxygen exceeds their demand for methane by a factor of 2–3.

Cultivating microorganisms on methane, compared to growing them on other substrates, has both Advantages and disadvantages.

The advantages include the purity of natural gas, which, unlike petroleum paraffins, contains no substances that need to be removed from the biomass. In addition, natural gas is easily transported through pipelines.

The disadvantages of natural gas as a substrate include its poor solubility in the culture medium, the slow growth rate of methane-oxidizing bacteria, increased oxygen consumption (5 times higher than on CARBOHYDRATES and 2–2.5 times higher than on n-paraffins), and explosion hazard.

Research on using methane as a feedstock for protein production, initiated by Royal Dutch Shell (UK) in 1975, was rather quickly discontinued due to the insufficient efficiency of the equipment developed for this purpose. It turned out to be more profitable to chemically pre-oxidize methane into methyl alcohol and then use it as a substrate for cultivating microorganisms.

The feed bacterial biomass (gaprin) obtained from methane contains up to 75% protein, up to 5% Lipids, and up to 10% ash. In terms of its amino acid profile and nutritional value, this protein is comparable to fish meal or soybean meal.