GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

22. MICROORGANISMS AS OBJECTS OF BIOTECHNOLOGY

22.2. BIOMASS-BASED PREPARATIONS

22.2.2. Fertilizers

Nodule Bacteria preparations: rhizobin, rhizotorphin (nitragin). Rhizobin (a dry preparation) and rhizotorphin (a peat-based preparation) are bacterial fertilizers produced using active, viable ROOT-nodule bacteria of the genus Rhizobium, used to increase the yield of legumes such as peas, beans, soybeans, faba beans, alfalfa, lupines, etc. These preparations are also known as "nitragin".

Nodule bacteria preparations are effective only when in an active state. To ensure this, the culture must be provided with adequate moisture, nutrients, and gas exchange, and grow at an optimum Temperature. All these conditions can be easily met by choosing a suitable carrier substrate. Peat meets such requirements. Its main drawback is inconsistency, as peat often contains toxic substances that inhibit the growth of nodule bacteria.

In the former USSR, the peat-based preparation of nodule bacteria was first produced in the 1930s, although its industrial production was established much later. The production technology for the peat preparation known as "rhizotorphin" was developed at the All-Union Research Institute of Agricultural Microbiology of VASKhNIL.

The most common method of applying rhizotorphin is pre-sowing Treatment of legume seeds. For this purpose, the seeds are moistened with 2.0-2.5% Water, rhizotorphin is added, and the mixture is processed in seed-treating machines. The application rate of rhizotorphin is 200 g per hectare-dose of any legume seeds. The treatment is carried out on the day of sowing. Crop yields increase by 1-10 centners per hectare.

To obtain rhizobin, the culture broth after cultivation of rhizobia is subjected to Separation, resulting in

biomass in the form of a paste with a moisture content of 70-80%. The paste is mixed with a protective medium (containing molasses and thiourea in a 20:1 ratio) and dried in vacuum drying ovens at 30-35 C and a gauge pressure of 10-13 kPa.

Preparations of free-living nitrogen fixers (azotobacterin). Azotobacterin is a bacterial fertilizer produced using a culture of the free-living soil nitrogen fixer Azotobacter chroococcum. Azotobacterin is available in dry and peat-based (soil) forms.

Phosphobacterin. This is a bacterial fertilizer containing spores of Bacillus megaterium var. phosphaticum. These bacteria are capable of converting complex organophosphorus compounds (Nucleic Acids, Nucleoproteins, etc.) and sparingly soluble mineral phosphates (pyrophosphates, polyphosphates) into a form accessible to plants. In addition, the bacteria synthesize BIOLOGICALLY ACTIVE SUBSTANCES (in particular, Vitamins) that stimulate plant growth. Phosphobacterin is not a substitute for phosphate fertilizers and does not work without them. It is a preparation with a stimulating effect.