Synthetic media for production of quality xanthan gum in 20 liter fermentors

Abstract

SummaryXanthan gum is a heteropolysaccharide synthesized by Xanrhomonas cumpestris NRRL B-1459 and is composed of D-glucose, D-mannose, and D-glucuronic acid, in addition to acetic and pyruvic acids. Different amounts of pyruvic acid ketal are found in various preparations which can influence the viscosities of dilute xanthan solutions. Polysaccharide production on synthetic media was studied in small-scale fermentors. Fermentation conditions were established for production of both high and low pyruvic acid gums (about 4 and 2% pyruvic acid, respectively). Low nitrogen [O. 1% (NH4),HP04)] and air (0.25 vol/liter/min) levels favor production of low pyruvate gum; increasing (NH,),HPOI to 0.15%, adding K2HP04, and increasing the air flow to 1.5 vol/liter/min favored production of normal gum. Both processes gave xanthan yields of 50 to 6096, based on 2.5% initial D-glUCOSe substrate, in two to three days. Differences in pyruvic acid content and in the quantity of gum produced under a given set of conditions were attributed to strain variability. Substrains were isolated that have desirable characteristics for production of xanthan gum; i.e., the ability to give good yields of high-pyruvate gum when grown on both complex and synthetic media.

Goma xantana: produção, recuperação, propriedades e aplicação

“…Durante o período de inoculação, ocorre um aumento da concentração celular, mas diminui a produção de goma xantana, porque a goma ao redor da célula impede o transporte de nutrientes e extende a fase lag de crescimento (Cadmus et al, 1978;De Vuyst et al, 1987;Pons et al, 1989;Pons et al, 1990).…”

“…As variáveis estudadas no trabalho de Casas et al (2000) são principalmente aquelas que mostram influência no conteúdo de ácido pirúvico. A influência da temperatura tem sido estudada somente para o grau de piruvação, e todos os autores acreditam que o conteúdo de piruvato máximo é obtido em 27°C (Cadmus et al, 1978;Tako e Nakamura, 1984;Shu e Yang, 1990;Peters et al, 1993).…”

“…O que se sabe é que elas são dependentes do: peso molecular médio e do conteúdo de acetato (Tako e Nakamura, 1984) e piruvato (Peters et al, 1993). Os níveis de ácido pirúvico e substituições de acetal na molécula podem variar com as condições do crescimento (Cadmus et al, 1978), as condições operacionais (Peters et al, 1993) e também a Xanthomonas sp usada (Kennedy e Bradshaw, 1984).…”

Effect of citric acid on the biosynthesis and composition of xanthan.

“…In continuous fermentation, this pyruvic acid to acetic acid ratio and molecular weight increased with an increase in citric acid concentration in feed. High agitation and aeration has been reported to increase pyruvic acid content in xanthan (Cadmus et al, 1987). This study showed that citric acid increases the pyruvic acid content both in aerobic and oxygen-limited conditions.…”

Goma Xantana: características e condições operacionais de produção

“…A produção de xantana tem sido avaliada na faixa de temperatura de 20 a 38 °C (CADMUS et al, 1978;GUPTE;KAMAT, 1997;LEELA;SHARMA, 2000). A maioria dos autores estabeleceu 28 °C como temperatura ótima de produção de xantana.…”