Location and limitation of cellulose production by Acetobacter xylinum established from oxygen profiles

Environmental modification and niche construction: developing O2 gradients drive the evolution of the Wrinkly Spreader

“…The transition zone between the two regions sees a change from 100-50% of normal O 2 levels to o1% in 1200 mm and is established within 5 h by a relatively small number of colonists. Similar rapid changes in O 2 gradients have been observed in flow-cell biofilms (Costerton et al, 1995;De Beer and Kü hl, 2001;Stewart and Franklin, 2008), G. xylinus A-L interface biofilms (Verschuren et al, 2000) and in natural systems including marine sediments, paddy fields and soil aggregates (Sexstone et al, 1985;Lü demann et al, 2000;Noll et al, 2005). It appears that many microbial habitats are characterised by very steep O 2 gradients and the infiltration of O 2 into these usually dominates the spatial structure of microbial communities (Fenchel and Finlay, 2008).…”

“…xylinus biofilms are thought to develop by growth at the top surface which displaces older layers further into the liquid column (Schramm and Hestrin, 1954). SBW25 O 2 uptake rates are 170 Â lower than that measured for G. xylinus (though comparable with P. aeruginosa) (Verschuren et al, 2000;Geckil et al, 2001). This difference may explain why the transition zone is twice the depth in WS biofilms and suggests that WS metabolic activity may extends to a greater depth than in G. xylinus biofilms.…”

“…In the G. xylinus biofilm, cellulose expression and probably growth is restricted to a zone 50-100 mm below the A-L interface defined by downwarddiffusing O 2 and upward-diffusing nutrient (Verschuren et al, 2000). Motile bacteria are generally guided by chemotaxis in search of nutrients, but when cellular energy levels are stressed, aerotaxis and other energy-taxis behaviours dominate even strong chemotaxis responses (Taylor, 2004).…”

“…O 2 availability was posited to be a significant factor in the fitness advantage of the WS (Rainey and Travisano, 1998) and preliminary experiments using mineral oil to reduce O 2 diffusion to the A-L interface suggested that it was a limiting factor in biofilm formation (Spiers et al, 2003). O 2 is limiting in the A-L biofilm produced by Gluconacetobacter xylinus (formerly Acetobacter xylinum); like the WS biofilm, it also utilises a cellulose-based matrix though the G. xylinus biofilm can reach depths of 12-22 mm after 15 days (Verschuren et al, 2000 and references therein), some 10 Â deeper than WS biofilms (Spiers et al, 2003). O 2 availability is also known to limit growth in flow-cell (submerged/solid-liquid interface) biofilms under conditions where nutrients are not limiting (Costerton et al, 1995;De Beer and Kü hl, 2001).…”

Cellulose Expression in Pseudomonas fluorescens SBW25 and Other Environmental Pseudomonads

“…are probably better adapted to growth in static liquid conditions than environmental isolates recovered from rotting fallen fruit [44] and under the right conditions, some can produce a gelatinous 'plug' up to 20 mm deep in 10-12 days [45]. In these, cellulose expression and probably growth, is restricted to a thin 50-100 μm deep zone at the top, where it is limited by O2 diffusing from above and nutrients diffusing through the mature biofilm from below [45]. The growing biofilm is maintained in position by the accumulation of small CO2 bubbles and by pressing against the walls of the container as it develops.…”