Effect of growth temperature on the morphology and performance of Zymomonas mobilis ATCC 29 191 in batch and continuous culture

Abstract

Summary. Increasing the temperature in chemostat culture of Zymomonas mobilis ATCC 29 191 with low and high glucose concentrations was found to result in a decreasing frequency of septation leading to the formation of long filaments and in increasing outer membrane blebbing. Whether this effect is strain specific or universal in Zymomonas is, unknown. Improvements in the fermentation kinetics could be achieved at elevated temperatures, with an optimum at 33°C.

Investigation of the impact of a broad range of temperatures on the physiological and transcriptional profiles of Zymomonas mobilis ZM4 for high-temperature-tolerant recombinant strain development

“…Within the temperature range of 24–45 °C, cells gradually changed from a short rod shape to a filament shape as the temperature increased (Fig. 1 a, b), which was consistent with previous studies [ 20 , 27 ]. At the same time, the results of the flow cytometer were also consistent with those of the microscopic ones (Fig.…”

“…Previous studies indicated that temperature affected the growth and ethanol production of Z. mobilis with biomass and ethanol production reduced at higher temperatures [ 14 , 18 , 19 ]. Temperature also affected the morphology of Z. mobilis , and the cell shape changed from short rods under optimal temperature to elongated filaments under high temperature, which is similar to the morphology under other stress conditions such as wood hydrolysate, molasses, urea or various salts [ 20 – 22 ]. Stevnsborg et al discovered that the shape of Z. mobilis cells returned to normal short rods from filaments when the culture temperature was reduced from 36 to 30 °C, and proposed that the arrest of septation and cell division was due to temperature-sensitive enzymes involved in septation [ 20 ].…”

“…Kosaka et al further reported that cell elongation of Z. mobilis was repressed by Mg 2+ at 39 °C [ 21 ]. Although the detailed mechanism behind this phenomenon is not clear, the activity of temperature-sensitive enzymes involved in septation may be stabilized by the Mg 2+ at 39 °C [ 20 ].…”

Metabolic shifts in Zymomonas mobilis in response to growth conditions

“…Perhaps the greatest obstacle to commercialization is that, compared to yeast, much less practical experience exists for the Z. mobilis fermentation. The extensive work done in the field of evaluation and optimization of fermentation techniques (recent publications: [82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99]) reflects the neccessity for the development of Z. mobilis-specific processes, especially those that can operate stably in a non-sterile environment. The narrow range of substrates utilized by Z. mobilis (i.e., glucose, fructose and sucrose), the formation of by-products in fructose and sucrose-containing media and the low salt tolerance are disadvantageous for commercial applications.…”

Alcoholic fermentation of cellulose hydrolysate by Zymomonas mobilis

“…This filamentous growth has already been reported in inhibitory conditions such as high temperature (Stevnsborg et al, 1986) or high salt concentration (StevnsborgandLatiord, 1986).Bycontrast, the mutant strain Cl07 showed a majority of rod shape cells. This result suggested that inhibition effects were less important with strain Cl07 than with strains ZM4 and SBE15.…”