Actinomycetes University of Udine, Mycology Department ISSN: 0732-0574 Vol. 7, Num. 3, 1996

INFLUENCE OF GROWTH CONDITIONS ON EXTRACELLULAR LECTIN SYNTHESIS BY STREPTOMYCETES

V. E. KOZYRITSKAYA, H. V. VALAGUROVA, A. A. PINDRUS, E. A. KOVALENKO and K. I. ANDREYUK

Institute of Microbiology and Virology, Kyiv, Ukraine

Code Number:AC96012
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ABSTRACT.

The influence of culture age, medium pH and composition, cultivation temperature on extracellular lectin formation by soil streptomycetes was studied. The regulation of the process by growth conditions is discussed.

The widespread capability of soil streptomycetes to produce lectins was illustrated in a previous paper (Kozyritskaya et al., 1996). Streptomyces species form extracellular lectins (Galinskaya et al., 1979; Fujita-Yamaguchi et al., 1982; Kameyama et al., 1982) with D-mannose, D-galactose and L-fucose specificity. Lectins with fucose specificity (SFL) were first discovered in Streptomyces sp. 16-3 and later in other strains (Kameyama et al., 1982).

The present work is devoted to the study of lectin synthesis under various growth conditions.

MATERIALS and METHODS

Organisms.

The tested Streptomyces strains were isolated from grey podzolic soil experimentally polluted with heavy metals and showed an hemagglutinating activity (HAA) equal to 64-258 Units of HAA (Kozyritskaya et al., 1996).

Growth conditions. Strains were grown, as previously described, and analysed after 1 to 7 dd incubation at 20, 28-30 and 40-42 C at pH 6.0, 7.0 and 8.0, and with different carbohydrates (Table 1).

RESULTS and DISCUSSION

Culture age.

The maximum level of HAA was different for the tested Streptomyces strains (Fig. 1). Streptomyces sp. 51 showed the highest HAA on the third day of cultivation. Two other isolates had a lower HAA but were characterised by two peaks of activity. The first peak was observed on the second day of cultivation and the second peak on the fourth and on the seventh day, for strains Streptomyces sp. 545 and 342 respectively. In addition the second peaks were higher than the first ones (Fig. 1).

Figure 1. Production of extracellular lectins at different times of incubation in three Streptomyces strains (1, 2 and 3: strains 51, 342 and 545 respectively)

Temperature.

In the range of tested temperatures a positive correlation was observed between increasing temperature and HAA (Fig. 2). At optimum growth temperatures HAA was markedly lower except for strain 545. At 20 C HAA was strongly reduced in the latter strain.

Figure 2. Effect of incubation temperature on lectin production by three Streptomyces strains

Medium pH. Lectin formation by the investigated strains was best at the optimum pH for growth (pH 7.0). An exception is represented by Streptomyces sp. 545 which showed maximum HAA (128 Units) at pH 6.0 (Fig. 3).

Figure 3. Effect of medium pH on lectin production by Streptomyces strains

Carbohydrates. Despite the lectin - carbohydrate relationship we were unable to establish a clear correlation between carbohydrate supplied to the medium and lectin. Results obtained with two Streptomyces strains are summarised in Table 1.

Table 1. Effect of different carbohydrates on lectin production by two Streptomyces strains

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Carbohydrate        Streptomyces sp. 342     Streptomyces sp. 545
(HAA Units)             (HAA Units)
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L-Arabinose                 8                       4
D-Xylose                    2                       2
D-Galactose                 2                       4
D-Glucose                   2                       2
D- Mannose                  2                       0
L-Rhamnose                  0                       4
D-Fructose                  0                       2
D-Lactose                   2                       8
Maltose                     0                       8
Sucrose                     0                       2
Raffinose                   2                       2
Cellobiose                  8                       8
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Results obtained stress the high variability of lectin synthesis by soil streptomycetes. Although it appears possible to regulate the process by changing growth conditions, these appear to vary according to the different lectin producer and in any case further work is needed on this subject.

REFERENCES

Fujita-Yamaguchi, G., K. Oishi, K. Suzuki & K. Imamori (1982). Studies on carbohydrate binding to a lectin purified from Streptomyces sp. Biochim. Biophys Acta, 701: 86-92

Galinskaya, E.L., Z.G. Naumenko & V.P. Pomyluyko (1979). Isolation and some characteristics of hemagglutinins from Actinomyces streptomycini 32-12. Appl. Biochem. Microbiol., 15: 581-589. (in Russian)

Kameyama, T., F. Ishikawa, K. Oishi & K. Aida (1982). Comparison of L- fucose-specific lectins produced by six strains of Streptomyces. Agric. Biol. Chem., 46: 523-528

Kozyritskaya, V.E., H.V. Valagurova, A.A. Pindrus & K.I. Andrejuk (1996). Hemagglutinating activity of streptomycetes from natural and heavy metal polluted soils. Actinomycetes, 7: ??-??

Podgorsky, V.S., E.A. Kovalenko, I.A. Symonenko (1992). Bacterial Lectins. Nauk. Dumka, Kyiv, 203 pp. (in Russian).

Copyright 1996 C.E.T.A., The International Centre for Theoretical and Applied Ecology, Gorizia

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