Reproducibility of Pilot Scale Xanthan Fermentations

Abstract

The reproducibility of results is an essential prerequiste for a successful systematic analysis of the influence of process development parameters on fermentation performance. Concerns of inoculum inconsistency and strain instability in Xanthan fermentations have led to the use of a highly productive variant of Xanthomonas campestris NRRL-B1459 under strict preservation protocols and the development of an improved, yet simple inoculation strategy. This technique allows the propagation of standardized inocula, ensuring that starter cultures both identical in concentration and history are used. Implementation of this methodology resulted in extremely reproducible cultivations in shake flask and in fermenters of up to a pilot scale of 150 L in volume.

Agitator speed and dissolved oxygen effects in Xanthan fermentations

“…This is to ensure that not only are the results repeatable, but also to distinguish the limits of biological variability from the effects of changing process parameters. We have previously reported such a study (Amanullah et al, 1996a) where the results of duplicate fermentations did not vary by more than ±5% at 5-, 20-, and 150-L scales of operation.…”

Biopolymer production using fungus Mucor racemosus Fresenius and glycerol as substrate

“…According to the literature, this behavior has been found in polymer solution microbial polysaccharides [22] . Beyer et al [23] found that 1% solutions of polysaccharide produced by Rhizobium CB744 at 25 °C, also promoted a decrease in viscosity with increasing shear rate.…”

Goma Xantana: características e condições operacionais de produção

“…Existem duas maneiras gerais de estudar aspectos reológicos: a primeira consiste em desenvolver expressões matemáticas, que possam descrever os fenômenos reológicos sem fazer maiores referências a suas causas, e a segunda consiste em correlacionar o comportamento mecânico observado com a estrutura detalhada do material em questão (SHAW, 1975). Por meio da análise reológica, ou seja, de análises de viscosidade e viscoelasticidade, têm-se um indicador da qualidade do polímero (AMANULLAH et al 1996;MARCOTTE;HOSHAHILI;RAMASWAMY, 2001).…”

“…Grande parte da literatura referente à produção de xantana está baseada em cepas obtidas de coleções de cultura, principalmente Xanthomonas campestris pv campestris NRRL B-1459 e seus derivados (SOUW; DEMAIN, 1980;JANA;GHOSH, 1995;AMANULLAH et al, 1996;YOO;HARCUM, 1999;CASTRO;LÓPEZ et al, 2004). Porém, o isolamento de microrganismos a partir de recursos naturais é uma importante ferramenta na busca de cepas que apresentem alta produção de xantana com qualidade reológica (TORRESTIANA; FUCIKOVSKY; GALINDO, 1990;THOMAS, 1995;GUPTE;KAMAT, 1997;ANTUNES et al, 2003).…”