JPH0661269B2 - Microbial flocculant production enhancement method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a Nocardia restrictor KR-I-3 (FERM4169).
No.) culturing a Nocardia microorganism having a flocculant-producing ability to produce a microbial flocculant, a carbon source and an organic nitrogen source are selected, and the initial pH is neutral to alkaline. The present invention relates to a method for enhancing the production of a microbial flocculant by culturing it in a region and suppressing excessive aeration.

[Prior art]

Conventionally, inorganic flocculants and synthetic polymer flocculants have been used as agents for treating activated sludge and civil engineering dredging. However, among the synthetic polymer flocculants, although they are superior in terms of capacity and economical efficiency, it is a reality that problems have been pointed out in terms of safety and secondary pollution as in the case of polyacrylamide type. Is. Overcoming and eliminating these problems, the development of new coagulants from the perspective of environmental protection and safety has been earnestly desired not only in the wastewater treatment field but also in all fields. The importance of this has been recognized.

〔Purpose〕

Therefore, the present inventors have already developed a microbial flocculant NOC-1 (Patent No. 1096062 (Japanese Patent Publication No.
56-39633)), and we are now studying a more efficient method to enhance the production of this aggregating agent.
It was confirmed that the production of the present flocculant can be enhanced very effectively by selecting H and the amount of aeration, and the present invention has been completed.

〔Constitution〕

According to the present invention, when a microorganism belonging to the genus Nocardia and having an aggregating ability is cultured to produce a microbial aggregating agent NOC-1, a yeast extract, casamino acid, and a substance containing at least one selected from peptone are included. Add as an organic nitrogen source, adjust the initial pH to pH 7.0 to 11.0, and limit the ventilation ratio represented by the following formula to 1 or less. Provided is a method for enhancing production of a microbial flocculant NOC-1 characterized by [R = aeration ratio, V ₁ = aeration amount of atmospheric air per minute (), V ₂ = volume of culture solution ()]. .

The physicochemical properties of the microbial flocculant NOC-1 (hereinafter referred to as microbial flocculant) are described in JP-B-56-39633 (Patent No. 1096062).

The strain used in the present invention may be any strain as long as it belongs to the genus Nocardia and has a flocculating ability with respect to sludge substances and the like, as a representative exemplified strain thereof, Nocardia restrictor KR-i-3 (FERM4169 No.) has been deposited.

By the way, as the medium for producing the present flocculant, any composition can be used as long as it is a medium in which the microorganisms having the flocculating ability can grow. As a general composition element, a carbon source and ammonium sulfate, an inorganic nitrogen source such as urea, and the like, KH ₂ PO ₄ , MgSO ₄ , a medium containing inorganic salts such as CaCl ₂ is used, but preferably It is preferable to culture under the medium composition and culture conditions shown.

Regarding the carbon source, when a water-soluble carbon source is used, high aggregation activity can be obtained by using a substrate such as glucose or fructose that exhibits a high growth amount, and the proportional relationship between the growth and the aggregation activity of the bacterium. Is recognized. On the other hand, when water-insoluble olive oil is used as a substrate, the agglutination activity is not high compared to the amount of culture. Of the inorganic nitrogen sources, ammonium sulfate and urea are good for flocculation activity. In the organic nitrogen source, a remarkable addition effect is recognized by yeast extract, casamino acid, and peptone. In addition, the optimal initial pH of the culture is in the neutral to alkaline range of 7 to 11, preferably in the weakly alkaline range of 8.5 to 9.5. The optimum culture temperature is preferably 30 ° C, but 25
Microorganisms show sufficient growth and agglutinating activity even at 37 ° C. The aeration rate is 1 or less in terms of the aeration ratio to the culture solution,
It was found that the aggregation activity per medium was higher when the range was preferably limited to 0 to 0.8. Collecting these results, it became possible to enhance the activity per medium by 8 times compared with the conventional method.

The aeration ratio to the culture solution in the present specification is represented by the following formula.

R = aeration ratio V ₁ = aeration amount of atmospheric air per minute () V ₂ = volume of culture solution () By the way, the agglutination target of the microorganism-producing aggregating agent is kaolin or the like from organic matter such as activated sludge. Although it has a wide range of inorganic properties, kaolin was selected as the substance to be aggregated in the aggregation titer measurement method. For the activity, the transparency of the supernatant was expressed as 1 / turbidity. That is, 0.5m of culture solution (object) was put into a 100m graduated cylinder, and after being made up to 10m with distilled water, 80m of kaolin suspension of 5000ppm and 10m of 10% calcium chloride salt were added, and after stirring for 5 minutes. The absorbance of the supernatant is measured at a wavelength of 550 nm. The agglutination activity was calculated as the value obtained by subtracting the reciprocal of the absorbance of the control from the reciprocal of the absorbance of the supernatant when the test solution was used. That is, the greater the reciprocal value, the greater the transparency and the higher the aggregation activity.

〔Example〕

 Next, the present invention will be described in more detail by way of examples.

Example 1 Glucose 1%, Urea 0.05%, K ₂ HPO ₄ 0.5%, KH ₂ PO ₄ 0.2
%, MgSO ₄ 0.02% medium 0.05% organic nitrogen source such as yeast extract was added to 100m medium 500m Erlenmeyer flask, adjusted to pH 7.5, and sterilized under pressure at 120 ℃ for 15 minutes. Later, Nocardia Restrictor KR-I-3 (FERM4169)
Was inoculated and cultured at 30 ° C., and the time-dependent change in the aggregating activity of each culture solution was examined.

Table 1 shows the maximum agglutination activity per 0.5 m of the culture broth by adding various organic nitrogen sources.

From these results, it was revealed that the flocculation activity of the culture solution was obviously increased by adding yeast extract, casamino acid, and peptone as the organic nitrogen source.

Example 2 The medium of Example 1 was supplemented with yeast extract as an organic nitrogen source.
Put 100m of the medium containing 05% into a 500m Erlenmeyer flask, adjust the initial pH of the medium to 6.0, 7.5, 8.5, 9.5, and
After sterilization under pressure at 15 ° C for 15 minutes, Nocardia restrictor KR-I-3 (FERM4169) was inoculated and cultured at 30 ° C, and the time-dependent change in aggregating activity of the culture solution was examined. Initial pH and each culture
The maximum aggregation activity value per 0.5 m is shown in Table-2.

Furthermore, this bacterium grows even when the initial pH of the medium is pH 10 or 11, and the culture fluid has agglutinating activity.

From the above results, it was found that the initial pH of the culture solution should be in the neutral to alkaline range for the production of the flocculant.

Example 3 The medium (pH 8.5) 2 shown in Example 2 was placed in a culture tank of a tabletop jar fermeter (manufactured by Maruhishi, 5 containers), and 120
After sterilization under pressure at ℃ for 15 minutes, Nocardia Restrictor KR
-I-3 (FERM4169) was inoculated, and the cells were subjected to aeration and agitation culture at 30 ° C and agitation speed of 500 rpm. The air flow rate was set to three levels of zero (air flow ratio: 0), 2 / min (air flow ratio: 1), and 4 / min (air flow ratio: 2). Table 3 shows the maximum cohesive force per 0.5 m of the culture broth obtained at each aeration ratio.

As a result, it was found that an excessive aeration amount is not preferable for the production of the highly active flocculant, and it is desirable to limit the aeration amount of the air so that the aeration ratio is 1 or less and culture.

[Effect] From the above experimental results, according to the present invention, the microbial flocculant can be efficiently produced.

Claims (1)

[Claims] 1. A material containing at least one selected from yeast extract, casamino acid and peptone when a microorganism coagulant NOC-1 is produced by culturing a microorganism which belongs to the genus Nocardia and has an aggregating ability. Is added as an organic nitrogen source, the initial pH is adjusted to pH 7.0 to 11.0, and the aeration ratio represented by the following formula is limited to 1 or less for aeration to enhance the production of the microbial flocculant NOC-1. Law. (R = aeration ratio, V ₁ = aeration amount of normal pressure air per minute (), V ₂ = volume of culture solution ())