Halomonas elongata strain Mar (=CCUG 52759) isolated from table-olive fermentation is the first halophilic bacterium to be shown to transform ferulic acid to vanillic acid under hypersaline conditions. During growth on ferulic acid, this strain was capable of promoting the formation of a significant amount of vanillic acid and trace quantities of vanillin. The products were confirmed by high-performance liquid chromatography and gas chromatography-mass spectrometry analyses. Based on the different metabolites identified, an oxidative side chain degradation pathway of ferulic acid bioconversion to vanillic acid was suggested. Phylogenetic analysis of 16S rRNA gene revealed that this isolated strain Mar was identified as H. elongata. To increase the formation of vanillic acid, a resting cell method using H. elongata strain Mar was performed. The optimal yield of vanillic acid (86%) was obtained after a 6 h reaction using 5 mM of ferulic acid and 4 g of dry weight of cells L(-1) pregrown on ferulic acid and harvested at the end of the exponential phase.

An aerobic, moderately halophilic, Gram-negative, motile, non-sporulating bacterium, strain LIT2T, was isolated from an oilfield-water injection after enrichment on crude oil. Strain LIT2T grew between 15 and 45 °C and optimally at 37 °C. It grew in the presence of 1–25 % (w/v) NaCl, with an optimum at 10 % (w/v) NaCl. Predominant fatty acids were C16 : 0 (26.9 %), C18 : 1 ω7c (22.6 %), C16 : 1 ω7c (20.4 %) C19 : 0 cyclo ω8c (10.9 %) and C17 : 0 (8 %). Interestingly, the relative percentages of these last two fatty acids were intermediate compared with most species among the family Halomonadaceae for which fatty acid composition has been determined. The DNA G+C content was 53.7 mol%, which is very low among the family Halomonadaceae. Strain LIT2T exhibited 16S rRNA gene sequence similarity values of 94.06–95.15 % to members of the genus Chromohalobacter, 94.21–94.65 % to members of the genus Halomonas and 93.57 % with the single species representative of the genus Cobetia. Based on the phylogenetic and phenotypic evidence presented in this paper, we propose the name Modicisalibacter tunisiensis gen. nov., sp. nov. to accommodate strain LIT2T. The type strain of Modicisalibacter tunisiensis is LIT2T (=CCUG 52917T =CIP 109206T). A reassignment of the descriptive 16S rRNA signature characteristics of the family Halomonadaceae permitted placement of the new genus Modicisalibacter into the family.

During growth on ferulic acid, Halomonas elongata DSM 2581 T was capable of promoting the formation of a significant amount of vanillic acid. The products were confirmed by high-performance liquid chromatography and gas chromatography mass-spectrometry analyses. To enhance the formation of vanillic acid and prevent its degradation, a resting-cell method using Halomonas elongata was developed. The growth state of the culture utilized for biomass production, the concentration of the biomass, the amount of ferulic acid that was treated and the reutilization of the biomass were optimized. The optimal yield of vanillic acid (82%) was obtained after a 10-h reaction using 10 mM ferulic acid and 5 g/l of cell pregrown on ferulic acid and harvested at the end of the exponential phase.