Transfer and consumption of oxygen during the cultivation of the ectomycorrhizal fungus Rhizopogon nigrescens in an airlift bioreactor

Abstract

The study had the objective of examining the aspects involved in the cultivation of ectomycorrhizal fungi for the production of commercially sustainable inoculant to attend the demands of the seedling nursery industry. It focused on certain parameters, such as the oxygen consumption levels, during the cultivation of the ectomycorrhizal fungus Rhizopogon nigrescens CBMAI 1472, which was performed in a 5-L airlift bioreactor. The dynamic method was employed to determine the volumetric coefficient for the oxygen transfer (k a) and the specific oxygen uptake rate (Q ). The results indicate that specific growth rates (μ ) and oxygen consumption decline rapidly with time, affected mainly by increases in biomass concentration (X). Increases in X are obtained primarily by increases in the size of pellets that are formed, altering, consequently, the cultivation dynamics. This is the result of natural increases in transferring resistance that are observed in these environments. Therefore, to avoid critical conditions that affect viability and the productivity of the process, particular settings are discussed.

Optimizing conditions of mycelial inoculum immobilized in Ca-alginate beads: a case study in ectomycorrhizal fungus Astraeus odoratus

“…To restore the disturbed DDF forest ecosystems, ECM inocula are needed to promote host plants and reestablish soil fertility. ECM inoculation has become a routine practice in nurseries; thus, the establishment of methods for inoculum production at an industrial scale is necessary (Brundrett et al 2005;Rossi et al 2007). Various inoculum types and formulations have been developed for the application (Repáč 2011).…”

“…The ideal ECM inoculum must contain su cient numbers of active propagules, retain viability throughout storage and transportation, and preserve their infectivity for several months after production. Additionally, the inoculum should be user-friendly, free of contamination, and the production process should be economically e cient (Rossi et al 2007; Charya and Garg 2019).…”

“…Mycelium inoculum has been considered the most suitable inoculation method due to the availability of previously selected isolates with high e ciency in promoting plant growth (Rossi et al 2007). Pure cultures of ECM fungi are grown in suitable solid substrates, such as a mixture of peat and vermiculite, supplemented with a nutritive solution.…”

“…According to nursery studies, ECM inoculum immobilized within alginate beads was proved to be more e cient than solid-state fermentation in the formation of ECM roots and the growth of seedlings (Tacon et al 1985;Mortier et al 1990). However, the low growth rates of ECM fungi in culture and the lack of information on physiology and kinetics of growth remain limitations for their application and mass production on an industrial scale (Oliveira et al 2006;Rossi et al 2007). In addition, the conditions to maintain the viability of mycelia entrapped within a calcium alginate bead need to be investigated for each ECM fungal species (Rodrigues et al 1999).…”

Fungal Cultivation and Production of Polysaccharides

“…This more "pure" mycelium comes from a biomass that is easily separated from the substrate. Cleaner mycelium yields polysaccharides that are easier to isolate, allowing for singular applications, such as pharmaceutical formulations (Ito and Sumiya 2000;Hölker et al 2004;Rossi et al 2004).…”