Increased Growth of the Microalga Chlorella vulgariswhen Coimmobilized and Cocultured in Alginate Beads with the Plant-Growth-Promoting Bacterium Azospirillum brasilense

ABSTRACT Coimmobilization of the freshwater microalga Chlorella vulgaris and the plant-growth-promoting bacteriumAzospirillum brasilense in small alginate beads resulted in a significantly increased growth of the microalga. Dry and fresh weight, total number of cells, size of the microalgal clusters (colonies) within the bead, number of microalgal cells per cluster, and the levels of microalgal pigments significantly increased. Light microscopy revealed that both microorganisms colonized the same cavities inside the beads, though the microalgae tended to concentrate in the more aerated periphery while the bacteria colonized the entire bead. The effect of indole-3-acetic acid addition to microalgal culture prior to immobilization of microorganisms in alginate beads partially imitated the effect of A. brasilense. We propose that coimmobilization of microalgae and plant-growth-promoting bacteria is an effective means of increasing microalgal populations within confined environments.

[1]  A. Tanaka,et al.  Application of immobilized growing cells. , 1990, Advances in biochemical engineering/biotechnology.

[2]  G. Holguin,et al.  Azospirillum – plant relationships: environmental and physiological advances (1990–1996) , 1997 .

[3]  G. Holguin,et al.  Root-to-Root Travel of the Beneficial Bacterium Azospirillum brasilense , 1994, Applied and environmental microbiology.

[4]  Michael A. Borowitzka,et al.  Micro-algal biotechnology. , 1988 .

[5]  Y. Bashan.  INOCULANTS OF PLANT GROWTH-PROMOTING BACTERIA FOR USE IN AGRICULTURE , 1998 .

[6]  G. Holguin,et al.  Nitrogen-fixation by Azospirillum brasilense Cd is promoted when co-cultured with a mangrove rhizosphere bacterium (Staphylococcus sp.) , 1996 .

[7]  M. Borowitzka.  Limits to Growth , 1998 .

[8]  J. Vanderleyden,et al.  Synthesis of phytohormones by plant-associated bacteria. , 1995, Critical reviews in microbiology.

[9]  J. Kloepper,et al.  Enhanced plant growth by siderophores produced by plant growth-promoting rhizobacteria , 1980, Nature.

[10]  G. An,et al.  Astaxanthin from Microbial Sources , 1991 .

[11]  Y. Bashan,et al.  Current status of Azospirillum inoculation technology: Azospirillum as a challenge for agriculture , 1990 .

[12]  Y. Wong,et al.  Wastewater inorganic N and P removal by immobilized Chlorella vulgaris , 1994 .

[13]  S. Baena,et al.  Efficiency of ammonia and phosphorus removal from a colombian agroindustrial wastewater by the microalgae Chlorella vulgaris and Scenedesmus dimorphus , 1997 .

[14]  M. Moo-young.  Bioreactor Immobilized Enzymes and Cells: Fundamentals and Applications , 1988 .

[15]  Y. Wong,et al.  Wastewater Nutrients (N and P) Removal by Carrageenan and Alginate Immobilized Chlorella Vulgaris , 1997 .

[16]  G. Holguin,et al.  Proposal for the division of plant growth-promoting rhizobacteria into two classifications : biocontrol-PGPB (plant-growth-promoting bacteria) and PGPB , 1998 .

[17]  G. Holguin,et al.  Isolation and Characterization of Plant Growth-Promoting Rhizobacteria , 1993 .

[18]  P. Chevalier,et al.  Behavior of algae and bacteria co-immobilized in carrageenan, in a fluidized bed , 1988 .

[19]  H. Claustre,et al.  Determination of chlorophylls and carotenoids of marine phytoplankton: separation of chlorophyll a from divinylchlorophyll a and zeaxanthin from lutein , 1996 .

[20]  B R Glick,et al.  Bacterial biosynthesis of indole-3-acetic acid. , 1996, Canadian journal of microbiology.

[21]  J. Fages.  An Industrial View of Azospirillum Inoculants: Formulation and Application Technology , 1992 .

[22]  J. Armitage,et al.  The role of taxis in the ecology of Azospirillum , 1992 .

[23]  I. Karube,et al.  Hydrogen evolution by co-immobilized Chlorella vulgaris and Clostridium butyricum cells , 1981 .

[24]  Y. Bashan,et al.  The fate of field-inoculated Azospirillum brasilense Cd in wheat rhizosphere during the growing season , 1987 .

[25]  W. Jacobs.  Are Angiosperm Hormones Present in, and Used as Hormones by, Algae? , 1986 .

[26]  G. Holguin,et al.  Root-surface colonization of black mangrove seedlings by Azospirillum halopraeferens and Azospirillu , 1999 .

[27]  Y. Bashan.  Alginate Beads as Synthetic Inoculant Carriers for Slow Release of Bacteria That Affect Plant Growth , 1986, Applied and environmental microbiology.

[28]  Bernard R. Glick,et al.  The enhancement of plant growth by free-living bacteria , 1995 .

[29]  J. A. Scott,et al.  Defined coimmobilization of mixed microorganism cultures , 1995 .

[30]  J. Ueckert,et al.  Continuous Culture Application in Physiological Investigations on Diazotrophic Bacteria , 1995 .

[31]  B. Glick,et al.  Methods in Plant Molecular Biology and Biotechnology , 1993 .

[32]  N. De Pauw,et al.  The potential of microalgal biotechnology: a review of production and uses of microalgae. , 1988, Biotechnology advances.

[33]  J. Tramper,et al.  Characteristics of and selection criteria for support materials for cell immobilization in wastewater treatment , 1996 .

[34]  J. Benemann,et al.  Bioremoval of heavy metals by the use of microalgae. , 1993, Biotechnology advances.

[35]  Y. Okon,et al.  Agronomic applications of azospirillum: An evaluation of 20 years worldwide field inoculation , 1994 .