USE OF GUAR DERIVATIVES FOR MICROORGANISMS GROWTH

Abstract

The present invention relates to the in vitro use of a guar derivative for maintaining or increasing the growth rate of microorganisms, wherein said guar derivative contains at least one anionic group.

Claims

1. A method, comprising maintaining or increasing the growth rate of microorganisms by using a guar derivative in vitro or on a plant, on a seed or in soil, wherein said guar derivative contains at least one anionic group.

2. (canceled)

3. The method of claim 1, wherein the microorganisms are fungi or bacteria.

4. The method of claim 1, for increasing the growth rate of microorganisms is increased.

5. The method of claim 1, wherein said anionic group is a carboxyalkyl group.

6. The method of claim 1, wherein said guar derivative exhibits a DS for anionic substituent groups ranging from 0.01 to 3.0.

7. The method of claim 1, wherein said guar derivative further contains at least one nonionic group.

8. The method of claim 17, wherein said hydroxyalkyl group is a C1-C6 hydroxyalkyl groups.

9. The method of claim 1, wherein said guar derivative has a degree of hydroxyalkylation comprised between about 0.1 and about 1.0.

10. The method of claim 1, wherein the guar derivative has an average molecular weight comprised between 100,000 g/mol and about 4,000,000 g/mol.

11. A method for maintaining or increasing the growth rate of microorganisms, the method comprising a step of contacting at least one seed with a guar derivative containing at least one anionic group.

12. (canceled)

13. A biostimulant composition comprising at least one microorganism, and at least one guar derivative containing at least one anionic group.

14. A kit comprising at least one microorganism, and at least one guar derivative containing at least one anionic group.

15. (canceled)

16. A seed coated with the biostimulant composition of claim 13.

17. The method of claim 7, wherein the at least one nonionic group is a hydroxyalkyl group.

18. The method of claim 8, wherein the hydroxyalkyl group is a C1-C6 hydroxyalkyl group selected from the group consisting of a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group and a hydroxybutyl group.

19. The method of claim 18, wherein the hydroxyalkyl group is a hydroxypropyl group.

20. The biostimulant composition of claim 13, wherein the at least one microorganism is a bacterium.

21. The kit of claim 14, wherein the at least one microorganism is a bacterium.

Description

EXAMPLES

[0103] The following materials are used in the experiments:

[0104] Guar: a carboxymethyl hydroxypropyl guar having an average molecular weight between 2,000,000 g/mol and 4,000,000 g/mol, a DSanionic between 0.05 and 0.20 and having a degree of hydroxyalkylation between 0.1 and 1.0, available from Solvay (provided as a powder)

[0105] Bacteria strains were acquired from Tropical Culture Collection in André Tosello Foundation—Brazil. [0106] Bacillus subtilis CCT 0089 [0107] Bacillus megaterium CCT 0536 [0108] Bradyrhizobium japonicum CCT 4065

[0109] All strains were stored at −80° C. in the appropriated culture media, containing 15% of glycerol.

[0110] Two different culture media were used in the experiments: [0111] NA media containing per liter: 3 g of meat extract, 5 g of peptone and 15 g of agar (for solid media only) [0112] YMA media containing per liter: 0.5 g of monobasic potassium phosphate, 0.2 g of magnesium sulphate; 0.1 g of sodium chloride; 0.5 g of yeast extract; 10 g of mannitol (for inoculum and solid media only); 5 mL of a 5% bromothymol blue solution and 15 g of agar (solid media only).

[0113] For strains Bacillus subtilis and Bacillus megaterium, NA media was used. For strain Bradyrhyzobium japonicum, YMA media was used. These media were selected according to strains supplier.

[0114] A 250 mL shake flask containing 100 mL of NA or YMA culture media, was inoculated with 1 mL of the stock culture and incubated at 30° C., 150 rpm for 72 hours.

[0115] For each strain, 10 mL of the reactivation media were then transferred into a 250 mL shake flask containing 100 mL of the same media, with the addition of guar powder (at 1 wt % in the incubation media); and incubated at 30° C., 150 rpm, for 96 hours. An experiment without addition of guar powder is also performed for each strain as a control.

[0116] 100 μL samples of each experiments were taken after 0 h, 24 h, 48 h, 72 h and 96 h of incubation. These samples were diluted (the dilutions were variable according to strain growth, being from 1×10.sup.−5 up to 1×10.sup.−15) and the dilutions plated in solid NA or YMA media. The plates were incubated at 30° C. until appearance of colonies. After incubation, the number of colonies present in each dilution was counted and used to evaluate bacterial growth.

[0117] For bacterial growth rate determination, a graph of the log.sub.10(number of colonies) versus time of incubation was constructed. The straight line in this graph represents the exponential phase of bacterial growth and the angular coefficient represents the bacterial growth rate (μ).

[0118] The μ value was used to compare all the experiments and to evaluate the influence of guar addition on bacterial growth. For this set of experiments the ratio of microorganisms and guar is equal to 7.00×10.sup.5 CFU/g. The bacteria growth rate (μ) obtained for the different experiments are summarized in Table 1:

TABLE-US-00001 TABLE 1 Bacteria growth Composition rate (h.sup.−1) Bacillus subtilis CCT 0089 0.0647 Bacillus subtilis CCT 0089 + guar 0.0929 Bacillus megaterium CCT 0536 0.0605 Bacillus megaterium CCT 0536 + guar 0.0875 Bradyrhyzobium japonicum CCT 4065 0.0891 Bradyrhyzobium japonicum CCT 4065 + guar 0.1400

[0119] For the three strains, a higher value of bacteria growth rate is obtained in presence of guar. The addition of guar permits to increase the growth rate of these different strains of bacteria. In Table 2 are reported the relative increase or decrease of bacteria growth rate with the addition of guar compared to the control for each strain. An increase of bacteria growth rate between 44% and 45% is observed for the two gram positive bacteria (Bacillus subtilis and Bacillus megaterium), whereas a relative increase by 57% is observed for Bradyrhyzobium japonicum, a gram negative bacteria.

TABLE-US-00002 TABLE 2 Relative increase of bacteria Strain growth rate with guar addition Bacillus subtilis CCT 0089 44% Bacillus megaterium CCT 0536 45% Bradyrhyzobium japonicum CCT 4065 57%