Growth performance of rhizobacteria on water hyacinth (Eichhornia crassipes) juices and dehydrated powder

Abstract

In the present study, juice of water hyacinth (Eichhorina crassipes), either crude or from its successive dilutions (1:1, 1:10, 1:30, 1:50 v/v) supported the in vitro development of Bacillus megaterium, Bacillus subtilis, Azotobacter chroococcum and Rhizobium leguminosarum biovar Phaseoli with doubling time (23.1–63.0 min) which was comparable if not shorter, to that calculated using the standard laboratory -synthetic media (nutrient, N-deficient mannitol and yeast extract agar media; 48.0–64.8 min). Rhizospheric microorganisms of legume and non-legume plants successfully grew on surface-inoculated agar plates of crude and diluted juices of the macrophyte. Tea bags filled with the dehydrated powders (5 and 10 g l−1) of water hyacinth supported the in situ recoverability of total rhizobacteria in population densities (3 × 107 - >108 cfu.g−1), which were found to be comparable, if not excessive, to those enumerated on the recommended culture media. Morpho-physiological identification of some isolates that had developed on the plant juice and tea bag culture media, revealed that they are not akin to those cultured on the chemically-synthetic culture media; they possibly represent a portion of recommended media - unculturables. Keywords: Water hyacinth, Juices, Tea bags, Rhizobacteria, Unculturables