Study of pellet formation of filamentous fungi Rhizopus oryzae using a multiple logistic regression model

Abstract

Fungal pellet formation is an important topic of fermentation research. It has been reported that many factors such as agitation, medium nutrients, pH, polymer additives, and inoculum size influence the formation of fungal pellets. However, a few studies on the effects of all of these factors on fungal pellet formation have been reported. This paper conducted a comprehensive investigation using a completely randomized design (CRD) on a filamentous fungus, Rhizopus oryzae NRRL 395, in order to discover the effects of the above factors on fungal pellet formation. In addition, other factors, such as addition of biodegradable polymers and spore storage time that have not been reportedly studied were examined and their effects on pellet formation were investigated. A multiple logistic regression model was established to predict the probability of pellet formation using the above factors and their interactions as predictor variables. Model building and diagnostics were obtained using the Statistical Analysis System (SAS 9.0) program. The model developed in this study can be used to predict the pellet formation of other R. oryzae strains as well.

Co-Cultivation of Fungal and Microalgal Cells as an Efficient System for Harvesting Microalgal Cells, Lipid Production and Wastewater Treatment

“…Fungal self-pelletization has been observed for numerous filamentous strains and can be explained by coagulative and non-coagulative mechanisms [37], [38], [39], [15], [40]. The coagulative mechanism observed in representatives of Aspergillus spp , Basidiomycete spp , Phanerochaete spp involves spore coagulation leading to developments of aggregates/pellets.…”

Effects of soybean meal hydrolysate as the nitrogen source on seed culture morphology and fumaric acid production by Rhizopus oryzae

“…Fumaric acid production decreased significantly with increased ethanol production when oxygen is limited [6]. Extensive research has thus focused on how to control the fungal morphology and physiology (metabolism) for fumaric acid biosynthesis [7][8][9][10][11][12]. During submerged fermentation, filamentous fungi can grow into various morphologies, including free mycelia with hyphae dispersed in the fermentation broth, smooth and hairy pellets with a discernible core of highly entangled networks of hyphae, small loose mycelial clumps, and large densely aggregated mycelia [13,14].…”

Effect of Extracellular Factors on Growth and Dimorphism of Rhizopus oryzae with Multiple Enzyme Synthesizing Ability

“…It has been reported that many factors such as agitation, medium nutrients, pH, polymer additives, and inoculum size influence the formation of fungal pellets. However, a few studies on the effects of all of these factors on fungal pellet formation have been reported [15]. This paper conducted a comprehensive investigation on various factors effecting dimorphism in a filamentous fungus, R. oryzae PR7 with a normal filament-pellet cycle of 90 days and a potential producer of several extra cellular cellulolytic, amylolytic and other enzymes.…”