Carbohydrate Sources Influence the Microbiota and Flavour Profile of a Lupine-Based Moromi Fermentation.

Lupine-based seasoning sauce is produced similarly to soy sauces and therefore generates a comparable microbiota and aroma profile. While the koji state is dominated by Aspergillus oryzae, the microbiome of the moromi differs to soy moromi, especially in yeast composition due to the absence of Zygosaccharomyces rouxii and Debaryomyces hansenii as the dominant yeast. In this study, we monitored the addition of a carbohydrate source on the microbiome and aroma profile of the resulting sauce. Compared to previous studies, the usage of a yeast starter culture resulted in a sparsely diverse microbiota that was dominated by D. hansenii and T. halophilus. This led to a pH below 5 even after four months of incubation and most of the measured aroma compounds were pyrazines and acids. The addition of wheat and buckwheat resulted in a temporary change in the yeast consortium with the appearance of Z. rouxii and additional bacterial genera. The aroma profile differs in the presence of pyrazines and esters. Since no significant differences in the taste and odour of wheat-added and buckwheat-added sauce was sensed, both substrates influence the lupine sauce in a similar way.

Genome Sequence of the Diploid Yeast Debaryomyces hansenii TMW 3.1188.

Debaryomyces hansenii TMW 3.1188 is a halotolerant diploid yeast that was isolated from lupine moromi fermentation. Here, we report on the 24.77-Mbp genome of a diploid strain of the species D. hansenii.

Chromohalobacter moromii sp. nov., a moderately halophilic bacterium isolated from lupine-based moromi fermentation.

Three moderately halophilic strains, TMW 2.2308T, TMW 2.2299 and TMW 2.2304, were isolated from a lupine-based moromi fermentation. Initial identification based on their low molecular sub-proteome using mass spectrometry showed relation to the genus Halomonas, however, low score values indicated novelty. The comparison of 16S rRNA gene sequences placed these strains within the genus Chromohalobacter with C. japonicus CECT 7219T (99.67% 16S rRNA sequence similarity to strain TMW2.2308T), C. canadensis DSM 6769T (99.54%) and C. beijerinckii LMG 2148T (99.32%) being their closest relatives. However, average nucleotide highest identity values of TMW 2.2308T to C. beijerinckii LMG 2148T of 93.12% and 92.88% to C. japonicus CECT 7219T demonstrate that it represents a novel species within the genus Chromohalobacter with additional strains TMW 2.2299 (96.91%) and TMW 2.2304 (96.98%). The isolated strains were non-spore-forming, motile and able to grow at temperatures from 5 to 45 °C with an optimum at 37 °C. Growth of TMW 2.2308T occurs at 5 to 25% (w/v) NaCl with optimum growth between 10and 12.5%. The genome of TMW 2.2308T has a size of 3.47 Mb and a G + C content of 61.0 mol%. The polyphasic evidence lead to the classification of TMW 2.2308T, TMW 2.2299 and TMW 2.2304 as members of a novel species of the genus Chromohalobacter. We propose a novel species as Chromohalobacter moromii sp. nov., with TMW 2.2308T (=DSM113153T =CECT30422T) as the type strain.

Microbiota dynamics and volatile compounds in lupine based Moromi fermented at different salt concentrations.

Fermented soy sauces are used as food seasonings in Eastern countries and all over the world. Depending on their cultural origins, their production differs in parameters such as wheat addition, temperature, and salt concentration. The fermentation of lupine seeds presents an alternative to the use of soybeans; however, the microbiota and influencing factors are currently unknown. In this study, we analyse the microbiota of lupine Moromi (mash) fermentations for a period of six months and determine the influence of different salt concentrations on the microbiota dynamics and the volatile compound composition. Cultured microorganisms were identified by protein profiling using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16S rRNA gene amplicon sequencing provided an overview of the microbiota including non-cultured bacteria. The volatile compounds were determined by gas chromatography-mass spectrometry (GC-MS). At all salt concentrations, we found that Tetragenococcus halophilus (up to 1.4 × 109 colony forming units (CFU)/mL on day 21) and Chromohalobacter japonicus (1.9 × 109 CFU/mL, day 28) were the dominating bacteria during Moromi fermentation. Debaryomyces hansenii (3.6 × 108 CFU/mL, day 42) and Candida guilliermondii (2.2 × 108 CFU/mL, day 2) were found to be the most prevalent yeast species. Interestingly, Zygosaccharomyces rouxii and other yeasts described as typical for soy Moromi were not found. With increasing salinity, we found lower diversity in the microbiota, the prevalence-gain of typical species was delayed, and ratios differed depending on their halo- or acid tolerance. GC-MS analysis revealed aroma-active compounds, such as pyrazines, acids, and some furanones, which were mostly different from the aroma compounds found in soy sauce. The absence of wheat may have caused a change in yeast microbiota, and the use of lupine seeds may have led to the differing aromatic composition. Salt reduction resulted in a more complex microbiome, higher cell counts, and did not show any spoiling organisms. With these findings, we show that seasoning sauce that uses lupine seeds as the sole substrate is a suitable gluten-free, soy-free and salt reduced alternative to common soy sauces with a unique flavour.