Characterization of Clostridium thermocellum JW20

Abstract

Clostridium thermocellum JW20 (ATCC 31549), which was isolated from a Louisiana cotton bale, grew on cellulose, cellobiose, and xylooligomers and, after adaptation, on glucose, fructose, and xylose in the pH range of 7.5 to 6.1 with Topt of 60°C, Tmax of 69°C, and Tmin of above 28°C. Doubling times during growth on cellulose and cellobiose were 6.5 and 2.5 h, respectively. The G+C content of the DNA was 40 mol% (chemical analysis). Growth on cellulose as substrate was totally inhibited in the presence of more than 125 mM sodium sulfate, 300 mM sodium chloride, 250 mM potassium chloride, 200 mM calcium chloride, 125 mM magnesium chloride, 40 mM lactate, or 250 mM acetate. The ratio of the fermentation products ethanol to acetate plus H2 decreased when the culture was agitated. Agitation otherwise increased the rate of cellulose degradation in a growing culture but not under nongrowth conditions or with cell-free culture supernatant containing the extracellular cellulase. Shaking lowered the concentration of H2 in the culture broth and thus minimized inhibition by the H2 formed. Externally added H2 caused an increased formation of ethanol during growth on cellulose or cellobiose. However, at an atmospheric pressure as high as 355 kPa (50 lb/in2), H2 did not cause significant growth inhibition beyond an increasing lag phase (up to 24 h). Several criteria to specifically prove the purity of C. thermocellum cultures were suggested. was necessary. Although some special properties of C. thermocellum JW20 have been published and are therefore not further described in this report, a general description of strain JW20 becomes important owing to the published work on its cellulase (5, 12, 21; L. G. Ljungdahl, M. P. Coughlan, and F. Mayer, unpublished results). The strain proved to be well suited for ethanol production from cellulose in coculture with Thermoanaerobacter ethanolicus (L. G. Ljungdahl and

Isolation and characterization of two thermophilic cellulolytic strains of Clostridium thermocellum from a compost sample

“…Unlike other Cl. thermocellum strains (Freier et al 1988;Tachaapaikoon et al 2012), CS7 and CS8 exhibited no growth on glucose, CMC or xylose. They also showed no xylanase activities even after extended incubation, while most Cl.…”

“…Due to frequent contamination in cultures of thermophilic cellulolytic bacteria (Erbeznik et al 1997), three additional criteria described previously (Freier et al 1988) were also employed for the purity confirmation of the isolates: (i) absence of butyrate production (<0Á1 mmol l À1 ) and a final culture pH above pH 5Á9, (ii) no growth on glucose or cellobiose at 72 or 30°C and (iii) remaining cellulolytic after five consecutive subcultures on cellobiose.…”

Effect of O2concentrations onSulfolobus solfataricus P2

“…Sulfolobus solfataricus P2 cells (DSM 1617) were grown at 80 1C, 110 r.p.m. and pH = 3 on Brock medium (Brock et al, 1972) (Freier et al, 1988) and 2 g glucose. The cultures were inoculated with exponential-phase cells, at an initial density at 600 nm of 0.05.…”

Production, Purification and Partial Characterization of Four Lipases from a Thermophile Isolated from Deception Island

“…Axenic cultures of ID17 microorganism were aerobically grown in a liquid medium containing (g/l) 5.0 tryptone, [16]. The pH of the medium for growth was adjusted to 7.5 with NaOH and the growth temperature was 65°C.…”