JP6987758B2 - Algae growth material - Google Patents

Description

The present invention relates to an algae growing material, an algae growing method, and a method for producing an algae growing material.

A phenomenon called "isoyake" is occurring along the coast of Japan. It is considered that the cause is a lack of nutritional components such as iron in coastal areas, and various techniques for improving these have been proposed (Patent Documents 1, 2, 3, 4, 5).

Marine algae absorb various inorganic salts and grow, but iron is thought to be mainly particulate iron oxide in seawater. Particulate iron oxide aggregates and precipitates, which may make it inferior to algae. For this reason, in the above proposals, there are many techniques for blending a chelating agent such as humus.

Here, examples of humus include natural high molecular weight organic substances existing in soil and inland water. Specific examples thereof include lignite, those contained in peat, metabolites of bacterial groups and natural humic acid derived from animals and plants. In addition, as industrially produced rotten plant matter, there are many such as those obtained by oxidatively decomposing young charcoal such as brown charcoal (Patent Document 6), or synthetics such as alkali metal salts or alkaline earth metal salts of the oxidative decomposition products. (Patent Documents 7 and 8).

Due to the difference in solubility of the solution in pH, humic acid is classified into fulvic acid that does not precipitate even at pH 1.0 or lower, humic acid that dissolves at pH 1.0 or higher, and humin that does not dissolve at any pH range (non-patentable). Document 1).

When using these humus substances, it is considered important to control the average molecular weight of the humus substances. Focusing on fulvic acid among humic substances, there is also a proposal for an effective molecular weight fraction of fulvic acid with higher biological activity (Patent Document 9).

Japanese Unexamined Patent Publication No. 2006-345738 Japanese Unexamined Patent Publication No. 2009-179587 Japanese Unexamined Patent Publication No. 2015-107061 JP-A-2015-154726 JP-A-2015-167473A Special Publication No. 40-14122 Japanese Unexamined Patent Publication No. 60-18565 Japanese Unexamined Patent Publication No. 51-72987 Japanese Unexamined Patent Publication No. 2015-78155

Fujitake, Human Substances Research Vol3, P1-9, 2006

Although the effects of humus have been proposed as described above, the characteristics of humus that are more effective in seawater are not clear. In addition, since compost and humus soil containing humus are derived from natural products, there is a concern that the quality of humus may become unstable.

An object of the present invention is to provide an industrially stablely produced humic acid, and to provide an iron complex with a humic acid fraction which is stable in seawater and has a high growth promoting effect on living organisms.

For the humic acid fraction according to the present invention, humic acid extracted from the nitrate oxide of juvenile charcoal according to the International Society of Hulamic Acids Method (Non-Patent Document 1) is used, and ultrafiltration is performed to further enhance the effect on algae. It is characterized by being a complex of humic acid fraction obtained by molecular weight fractionation and iron.

According to the present invention, it is possible to provide an industrially produced stable humic acid and an iron complex with an effective humic acid fraction that exerts an effect of promoting the growth of marine algae.

Hereinafter, embodiments of the humic acid iron complex according to the present invention will be described.

The humic acid according to the present embodiment is humic acid obtained by oxidizing young charcoal such as lignite with nitric acid, and can be obtained by fractionating the extract of this humic acid by ultrafiltration. As the iron material according to this embodiment, salt such as iron chloride or slag fertilizer can be used. Mineral fertilizer is an easily available fertilizer and is a siliceous fertilizer made from steel slag or the like, but contains a large amount of iron as a by-product. These can be mixed in advance, but both components can be added to the medium or the like at the same time. Although this additive component behaves as an iron complex, it can also be expected to have secondary effects such as forming and stabilizing a complex with a metal such as copper as a medium component.

[Total organic carbon concentration]
The total organic carbon (TOC) concentration of the humic acid solution is a value measured by a combustion catalytic oxidation method using a total organic carbon meter (TOC-L manufactured by Shimadzu Corporation).

[Average molecular weight]
The average molecular weight of humic acid is a value measured by the HPSEC method (GPC method) using an Alliance HPLC System manufactured by Waters. The column was SB-803HQ manufactured by SHODEX, and the standard sample was sodium polystyrene sulfonate. The mobile phase is a 10 mmol / L sodium phosphate buffer containing 25% acetonitrile, and the detection wavelength is 260 nm.

[Manufacturing method of humic acid]
Here, "young coal" is coal having a low carbon content, and is defined as having a carbon content of 83% by mass or less. The juvenile charcoal is, for example, peat, lignite, lignite, subbituminous coal and the like, and one or a mixture of two or more of these is used. For example, after an oxidation reaction of lignite in a water bath at about 70 ° C. using nitric acid having a concentration of 48% by mass for about 1 hour, it is appropriately dried to obtain a crude humic acid product.

It is also possible to mix this crude humic acid product with mineral slag acid fertilizer and perform consolidation granulation or rolling granulation to obtain granulated products.

[Humic acid fractionation method]
From this crude humic acid, humic acid is prepared according to the International Society for Humus and Vegetables Law (Non-Patent Document 1). This humic acid is diluted with 0.05 mol / L phosphate buffer (pH 9) to obtain a humic acid solution.

The humic acid solution is ultrafiltered by the tangential flow method (also called the cross flow method) to obtain a fraction by molecular weight (Sartorius Technical Manual).
https://www.sartorius.co.jp/fileadmin/fm-dam/sartorius_media/Lab-Products-and-Services/Lab-Filtration/Ultrafiltration-Devices/Vivaflow/Manuals/Manual_Vivaflow50_200_SLU6097-e.pdf P11-21,
Supervised by the Japanese Society of Humus, "Humus in the Environment-its Characteristics and Research Methods-", P82-97, Sankyo Publishing, 2008)

The holding solution of each fraction is centrifugally washed by centrifugation (5000 × g, 30 minutes, 5 ° C.) with a pH of 1.0 by adding 6 mol / L hydrochloric acid. This operation is repeated 3 times to freeze-dry.

<Action effect>
Hereinafter, the action and effect of the humic acid fraction according to the above embodiment will be described.

The humic acid iron complex according to the present invention is a complex of nitric acid oxide of juvenile charcoal and iron, and can elute and stabilize iron in seawater, and further enhances biological activity by ultrafiltration to the molecular weight. It is characterized by being obtained by performing an image.

According to the present invention, it is possible to provide an effective iron humic acid complex that exerts an effect of promoting the growth of marine algae. It can also provide a more effective molecular size humic acid fraction to enhance the activity of algae.

Although these mechanisms are under intense research, the molecular size and stability constants of the compounds of humic acid and iron are important, and we believe that fractions that match the size distribution available to marine algae are most effective. Be done. It is inferred that these are deeply involved in the absorption of iron.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Stabilization of iron in seawater]
Lignite having a carbon content of 77% by mass was crushed, 500 g of powdered lignite passed through a 250 μm sieve was placed in a 2 L beaker, and 630 g of nitric acid having a concentration of 48% by mass was added. An oxidation reaction was carried out in a water bath at 70 ° C. for about 1 hour, and then the mixture was dried at 105 ° C. to obtain a crude humic acid product.

This crude humic acid product is mixed with 45% by mass of mineral acid fertilizer (trade name: Minekal, manufactured by Sangyo Shinko Co., Ltd.) as an iron material and 5% by mass of polyvinyl alcohol (manufactured by Denka Co., Ltd.) as a binder. After adding water as appropriate, compact granulation was performed and the mixture was dried at 105 ° C. A tablet granulated product having a diameter of 1 cm, a thickness of 0.6 cm, and a thickness of 0.5 g was obtained.

[Example 1]
One tablet product was placed in a 100 mL Erlenmeyer flask, and 60 mL of artificial seawater (manufactured by Wako Pure Chemical Industries, Ltd.) was added. After culturing at 120 rpm for 30 days, the supernatant was collected and the iron in the solution was quantified by an ICP emission spectrometer.

[Comparative Example 1]
The procedure was carried out in the same manner as in Example 1 except that 0.25 g of ore silicic acid fertilizer was used instead of the tablet. The solid-liquid ratio between the artificial seawater and the iron material is almost the same as that in the first embodiment.

As shown in the results of Table 1, in Comparative Example 1, in addition to the fact that the amount of dissolved iron is small, it is considered that the dissolved iron is coagulated and precipitated. It can be seen that in Example 1, the amount of iron eluted increased and the iron was stably dissolved over a long period of 30 days. As described above, it can be seen that the complex of humic acid obtained by nitric acid oxidation of lignite and iron exists stably in seawater.

[Cultivation test of molecular weight fraction]
Next, humic acid was prepared from this crude humic acid product according to the International Society of Huhumic Acid Society Law (Non-Patent Document 1). This humic acid was suspended in purified water, the pH was adjusted to 8.0 using a 1 mol / L sodium hydroxide solution, and the TOC concentration was diluted with purified water to 5000 mg / L. This solution was diluted with 0.05 mol / L Na ₂ HPO ₄ solution (pH 9) to prepare a humic acid solution so that the TOC concentration was 5 mg / L.

The humic acid solution was ultrafiltered under the conditions shown in Table 2 and fractionated into a permeate and a holding solution, respectively. Four molecular weight fractions of 100 kDa or more, 30 kDa or more and less than 100 kDa, 10 kDa or more and less than 30 kDa, 5 kDa or more and less than 10 kDa were obtained as retained fractions.

A cultivation test was carried out using wakame seaweed as a test material in a 250 mL polycarbonate container under the conditions shown in Tables 3 and 4.

Sporophytes with a leaf length of 0.5 cm were inoculated (transplanted), transplanted to a medium having the same composition every week, and cultured for 28 days while supplying air. The effect of the material was evaluated by the amount of wakame seaweed (leaf length excluding the leaf length at the time of inoculation).

[Example 2]
The culture medium was cultivated by adding a humic acid fraction of 100 kDa or more to the culture medium so as to have a TOC of 1.5 mg / L and iron chloride to a concentration of 0.3 μmol / L.

[Example 3]
The same procedure as in Example 2 was carried out except that a humic acid fraction of 10 kDa or more and less than 30 kDa was added instead of the humic acid fraction of 100 kDa or more.

[Example 4]
The same procedure as in Example 2 was carried out except that a humic acid fraction of 5 kDa or more and less than 10 kDa was added instead of the humic acid fraction of 100 kDa or more.

[Comparative Example 2]
Iron chloride was added to the culture solution so as to be 0.3 μmol / L and cultivated. No components such as humic acid fraction were added.

[Comparative Example 3]
The culture period was 14 days, and the same procedure as in Example 2 was carried out except that ethylenediaminetetraacetic acid (EDTA) was added at 10 mmol / L instead of the humic acid fraction of 100 kDa or more. EDTA 10 mmol / L corresponds to approximately TOC 1.5 mg / L.

[Comparative Example 4]
The culture period was 14 days, and the same procedure as in Example 2 was carried out except that diethylenetriamine pentaacetic acid (DTPA) was added at 10 mmol / L instead of the humic acid fraction of 100 kDa or more. DTPA 10 mmol / L corresponds to approximately TOC 1.5 mg / L.

As shown in the results of Table 5, the growth amount of the one to which the humic acid fraction was added increased as compared with the one to which only iron was added in Comparative Example 2. In addition, the effect is greater than that of the general chelating agents EDTA and DTPA shown in Comparative Examples 3 and 4. Among the molecular weight fractions of humic acid, the humic acid fraction of Example 3 having a humic acid fraction of 10 kDa or more and less than 30 kDa has a remarkable growth promoting effect, and the growth promoting effect can be enhanced by the molecular weight of humic acid.

Since the humic acid according to the present invention is an industrially produced humic acid, it is possible to stabilize the quality as compared with conventional compost and the like, and it is possible to supply a stable iron complex even in seawater. Further, the fractionated humic acid fraction of 10 kDa or more and less than 30 kDa has a growth promoting effect on algae with a small amount of addition. The humic acid according to the present invention is more effective than a chelating agent such as EDTA, and has biodegradability, so that there is no demerit such as remaining in the environment. In addition, the humic acid according to the present invention can also be used in coastal aquaculture and in recent years on land aquaculture.

Claims (8)

An algae growing material containing humic acid obtained by nitric acid oxidation of juvenile charcoal and having a molecular weight fraction of 10 kDa or more and less than 30 kDa. The algae growing material according to claim 1, wherein the humic acid is humic acid obtained by nitric acid-oxidizing one or more kinds of juvenile coal selected from the group consisting of peat, lignite, lignite, and bituminous coal. The algae growing material according to claim 1 or 2 , wherein the iron material is iron chloride or an ore silicic acid fertilizer. A method for growing algae using the algae growing material according to any one of claims 1 to 3. A method for producing an algae growing material, in which humic acid having a molecular weight fraction of 10 kDa or more and less than 30 kDa is prepared by nitric acid oxidation of juvenile charcoal, and the humic acid and an iron material are mixed. The method for producing an algae growing material according to claim 5 , wherein the humic acid is humic acid obtained by nitric acid-oxidizing one or more kinds of juvenile coal selected from the group consisting of peat, lignite, lignite, and bituminous coal. The method for producing an algae growing material according to claim 5 or 6 , wherein the iron material is iron chloride or an ore silicic acid fertilizer. The method for producing an algae growing material according to any one of claims 5 to 7 , wherein compact granulation or rolling granulation is used.