Joint Immobilization of Plant Growth-Promoting Bacteria and Green Microalgae in Alginate Beads as an Experimental Model for Studying Plant-Bacterium Interactions

Abstract

A simple, quantitative experimental model, offering a convenient and basic approach to studies of plantbacterium interactions, is proposed. This involves immobilizing a unicellular, freshwater microalga, a Chlorella species, serving as the plant, with a plant growth-promoting bacterium, an Azospirillum species, in small alginate beads to allow close interaction and to avoid external interference from bacterial contaminants.

Probiotic Biofilms

“…Azospirillum spp. significantly alters the metabolism of microalgae, mainly producing indole-3-acetic acid (IAA) [78] and increasing the nitrogen cycle enzymes in these algae [73]. Although several studies described that inoculation of marine phytoplankton and freshwater bacteria sometimes increase their productivity [74], these studies are descriptive and exploratory and there is no mechanism described or demonstrated by which the phenomenon occurs.…”

“…De Bashan and Bashan (2008) [78], proposed and studied a model of microalgae and bacteria immobilized in alginate to analyze and evaluate their possible interactions. In their study described the following sequence of events occurring during the interaction between the two microorganisms.…”

“…The most notable effect is the increasing by 2 to 3% on growth of microalgae with PGPB on those without PGPB [65]. This model proposed by Bashan and Bashan (2008) [78] has been evaluated in various combinations of microalgae-PGPB demonstrating the induction of growth in C. sorokiniana and B. pumilus, and others C. vulgaris and A. brasilense Sp6 [table 1; 78]. At cell and culture level there is an increase in the absorption of ammonium.…”

“…and the plant growth promoter bacteria (PGPB) Azospirillum brasilense, both bound and immobilized in alginate beads [116]. Each unit in this technological model, a single polymer sphere, contains within cavities that serve as matrix for the folding of microalgae and bacteria [66,78,119]. Additionally, the entrapment of microorganisms may also be within the solid matrix polymer of the polymeric sphere.…”

Biocontrol of Fusarium wilt of banana: Key influence factors and strategies

“…To achieve ideal biocontrol efficacy, the antagonists must colonize the rhizosphere soil and sustainedly occupy favorable ecological sites in the environment. Previous studies have illustrated that the long-term colonization of antagonists is correlated to soil moisture (or the water content of soil), temperature, soil aeration, pH, soil salinity, as well as the continuous supply of nutrients (Sessitsch et al, 2004;Bashan et al, 1991;Bevivino et al, 2005;Cavaglieri et al, 2005;de-Bashan and Bashan, 2008).…”