In vitro colonization and increase in nitrogen fixation of seedling roots of black mangrove inoculated by a filamentous cyanobacteria

Abstract

An isolate of the filamentous cyanobacterium Microcoleus sp. was obtained from black mangrove aerial root (pneumatophore) and inoculated onto young mangrove seedlings to evaluate N2-fixation and root-colonization capacities of the bacterium under in vitro conditions in closed-system experiments. N2 fixation (acetylene reduction) gradually increased with time and reached its peak 5 days after inoculation. Later, it decreased sharply. The level of N2 fixation in the presence of the plant was significantly higher than the amount of nitrogen fixed by a similar quantity of cyanobacteria on a N-free growth medium. The main feature of this root colonization was the gradual production of a biofilm in which the cyanobacterial filaments were embedded. Visible biofilm production increased with time until it completely covered the entire root system of the plant. The in-and-out movement of cyanobacterial filaments from the biofilm probably allows colonization of uncolonized portions of the root several days after the initial inoculation. This is, to the best of our knowledge, the first report of the artificial inoculation of cyanobacteria on marine mangroves.Key words: Avicennia germinans, beneficial bacteria, biofilm, black mangrove, diazotrophic cyanobacteria, Microcoleus sp., nitrogen fixation, plant growth-promoting bacteria, root colonization.

Synergism between Phyllobacterium sp. (N2-fixer) and Bacillus licheniformis (P-solubilizer), both from a semiarid mangrove rhizosphere

“…Yet, mangroves are alarmingly and systematically being deforested, similarly to rain forests [8,9]. To aid in the reforestation of mangroves, inoculation of the seedlings with plant growth-promoting bacteria (PGPBs) has been suggested [10,11,12], similarly to what has been done in agriculture [13^16] and temperate forestry [17].…”

“…Previous work on PGPBs that interact with mangroves includes the observation that the diazotrophic cyanobacteria Microcoleus chthonoplastes improved N 2 ¢xation [12] and nitrogen incorporation in black mangrove seedlings [10]. In addition, the terrestrial halotolerant bacterium Azospirillum halopraeferens [18] and halotolerant Azospirillum brasilense Cd [19] can successfully colonize black mangrove roots in seawater [11].…”

Biodiversity and temporal distribution of Chroococcales (Cyanoprokaryota) of an arid mangrove on the east coast of Baja California Sur, Mexico.

“…1995a;Branco et al 1996;Laursen & King 2000;Nogueira & Ferreira-correia (Bashan et al 1988). In this biotope, the main N 2 fixers were cyanoprokaryotes (ToLedo et al 1995b), implying that interaction of cyanoprokaryotes and mangrove seedlings is mutually beneficial and suggests the use of the first as inoculants for mangrove reforestation and rehabilitation. This paper provides information on biodiversity of cyanoprokaryotes of the most conspicuous populations of order Chroococcales that grow on Avicennia germinans pneumatophores from Zacatecas estuary, Baja California Sur, Mexico, an arid mangrove located in the southwestern Gulf of California.…”

Ecophysiology of Wild Plants and Conservation Perspectives in the State of Qatar

“…The filamentous cyanobacterium Microcoleus sp.was isolated and inoculated on to young mangrove seedlings. Such cyanobacterial filaments colonize the roots of mangrove by gradual production of biofilm [77]. Also, bacteria may influence the mangrove ecosystem directly; they contribute inevitably in the recycling of nutrients [78].…”