Partial bioenergetic characterization of Gluconacetobacter xylinum cells released from cellulose pellicles by a novel methodology

Abstract

Aims: Gluconacetobacter xylinum is well known for its ability to produce large amounts of cellulose, however, little is known about its cell physiology. Our goal was to study the respiratory metabolism and components of the respiratory system of this bacterium in static cultures. To reach our goal, a medium formulation had to be designed to improve cell growth and cellulose production together with a novel method for the recovery of cells from cellulose pellicles. Methods and Results: Successive modifications of a nutrient medium improved G. xylinum cell growth 4AE5-fold under static culture conditions. A blender homogenization procedure for the releasing of cells from the cellulose matrix gave a high yield of cells recovered. Respiratory activities of purified cells were greatly stimulated by exogenous substrates and showed to be resistant to KCN. Unexpectedly, exogenous NADH was oxidized at high rates. Cytochromes a, b, c and d were identified after spectral analyses. Conclusions: Partial bioenergetic characterization of G. xylinum cells allowed us to propose a scheme for its respiratory system. In addition, the growth medium for biomass production and the procedure for the efficient recovery of cells from cellulose pellicles were significantly improved. Significance and Impact of the Study: This work provides the first-ever bioenergetic characterization of G. xylinum grown in static cultures. In addition, a novel methodology to obtain purified cells in suitable quantities for biochemical research is described.

The unified metabolism of Gluconacetobacter entanii in continuous and batch processes

“…Reduced NADP can be oxidized by NAD. NADH and PQQH 2 yield electrons to ubiquinone, and the terminal oxidase (cytochrome b) transfers electrons from ubiquinone to oxygen [37]. The translocated protons are returned through the ATP synthase complex, with concomitant production of ATP [38].…”

Biossíntese e recentes avanços na produção de celulose bacteriana

“…Além de atuar como barreira física que protege a bactéria da radiação ultra-violeta, a CB aumenta a capacidade de colonizar substratos e seu caráter higroscópio permite a retenção de umidade prevenindo a desidratação do substrato [24]. Devido sua complexidade ainda hoje a G. xylinus tem sido considerada um organismo modelo para o estudo da biossíntese de celulose [2]. A síntese de celulose por G. xylinus constitui um complexo processo que envolve três etapas principais.…”

“…A primeira refere-se à polimerização dos resíduos de glicose em cadeias -glucana [2] [3] [4]. A segunda [1][2][3][4] etapa corresponde à secreção extracelular das cadeias lineares e a terceira corresponde à organização e cristalização das cadeias de glucanas, por meio de ligações de hidrogênio e forças de Van der Walls dispostas hierarquicamente em tiras [3]. O resultado desse processo é a formação de uma estrutura tridimensional resistente denominada microfibrila.…”

“…A biossíntese da CB depende de duas vias anfibólicas importantes, a via das pentoses e o ciclo de Krebs [2] [3]. A via das pentoses participa da oxidação dos carboidratos e, no ciclo de Krebs, ocorre a oxidação dos ácidos orgânicos.…”

Minerals consumption by Acetobacter xylinum on cultivation medium on coconut water

“…Many studies show that, for a good production of bacterial cellulose by strains of Acetobacter , culture media enriched with carbohydrates, proteins, vitamins, and inorganic salts are required (Baruque-Ramos et al , 2001; Budhiono et al , 1999; Chávez-Pacheco et al , 2005; Jagannath et al , 2009; Jonas and Farah, 1988; Son et al , 2003). In spite of being present in low concentrations, those minerals have a significant effect in the growing and production of bacterial cellulose (Weinhouse and Benziman, 1974).…”