Xylose and arabinose utilization by the rumen bacterium Butyrivibrio fibrisolvens

Abstract

The rumen bacterium Butyrivibrio fibrisolvens strain D1 co-utilized xylose and glucose in batch culture, but there was a marked preference for glucose over arabinose. When both pentoses were provided, xylose was preferred over arabinose. Strain D1 co-utilized a combination of either pentose and cellobiose, but preferred over maltose. Pentose sugars were depleted less rapidly in the presence of sucrose than controls containing only pentose. In contrast, B. fibrisolvens strain A38 exhibited a strong preference for disaccharides, including maltose, over either xylose or arabinose. Theoretical maximum growth yields for strain D1 in single-substrate continuous culture were highest for sucrose and cellobiose and the maintenance energy coefficient for arabinose was at least 3.8-fold greater than for other substrates. We suggest that B. fibrisolvens may have evolved a mechanism to utilize certain sugars before arabinose in order to avoid this high maintenance energy expenditure.

Pentose transport by the ruminal bacterium Butyrivibrio fibrisolvens

“…Previous work with B. fibrisoluens indicated that glucose and xylose were co-utilized but utilization rates of each sugar in dual substrate incubations were slower than rates in cultures provided with only a single carbohydrate [4]; this result suggested that the presence of glucose influenced xylose utilization. An interaction between xylose and glucose utilization was also evidenced by the fact that pulses of each sugar significantly decreased the utilization of the other sugar; a mutual non-competitive inhibition of transport was apparently responsible for these observations.…”

“…Transport activity of cells grown on different substrates suggested that xylose uptake was inducible, but the exact regulatory mechanisms controlling the expression of pentose permeases requires further study. Even though sucrose and cellobiose cultures had very low transport activity, cultures provided with either disaccharide and xylose showed at least some co-utilization of both sugars [4]; this result further implied that inductive control regulated xylose permease expression. In contrast, the strong preference for glucose over arabinose noted in the present as well as previous work [4] suggests that, in addition to induction, a level of repressive control exists in the case of arabinose transport.…”

“…Previous results indicated that B. fibrisolvens co-utilized a combination of glucose and x~lose when both sugars were present at the beginning of the incubation [4]. When glucose was added to a culture already growing on xylose, there was an abrupt decrease in the rate of pentose utilization (Fig.…”

“…In cultures containing only a single pentose, a colorimetric assay was used to measure pentose [8]; hexosc was differentiated from pentose by absorption difference at 660 nm versus 600 nm. In cultures containing both xylose and arabinose, alditol acetate derivatives of the sugars were prepared using a previously described method [4,9]. Intracellular ATP was measured with a Bio-Orbit Luminometer (LKB, Gaithersburg, MD) using luciferin plus luciferase [10], and bacterial protein was measured by the method of Lowry et al [11] after cell hydrolysis (0.2 N NaOH, 20 min, 100°C).…”

Relaxed control of sugar utilization in Lactobacillus brevis

“…Fibrolytic ruminal bacteria are able to degrade the hemicellulose of plant materials and utilize pentose sugars with glucose. Butyrivibrio fibrisolvens was reported to simultaneously consume glucose and xylose, although this effect was strain specific (Marounek & Kopecny, 1994;Strobel & Dawson, 1993). Ruminococcus albus consumed xylose and glucose simultaneously but the dominant repressor was cellobiose (Thurston et al, 1994).…”