Co-inoculation of Debaryomyces hansenii and lactic acid bacteria: a strategy to improve the taste and odour profiles of dry sausages

The effects of the co-inoculation of Debaryomyces hansenii separately with 3 lactic acid bacteria(LAB),Lactobacillus sakei,Lactobacillus plantarum and Lactobacillus curvatus,on the taste and odour profi les of dry sausages were investigated.The co-inoculated sausages showed higher free amino acid and organic acid contents than the non-inoculated control and sausages inoculated with D.hansenii alone.Meanwhile,the sausages inoculated with D.hansenii+L.plantarum,D.hansenii+L.sakei and D.hansenii+L.curvatus had the highest contents of aldehydes,esters and alcohols,respectively.The results of electronic tongue,electronic nose and sensory evaluation demonstrated that compared with the sausage inoculated with D.hansenii,the sour taste and fl oral odour increased and the fatty odour decreased in the sausage inoculated with D.hansenii+L.sakei;this was more favourable for the development of a desirable fl avour in sausages.Moreover,the partial least squares regression analysis indicated that 10 taste and 33 odour compounds were mainly responsible for the differences in the flavour profiles among the sausages.Overall,these findings contributed to a more comprehensive understanding of the formation of sensory characteristics in dry sausages co-inoculated with yeast and LAB.

Low-Density Co-Inoculation with Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 Promotes Plant Growth and Nitrogen Fixation in Soybean Cultivars

Inoculation density has a marked effect on nodulation and N fixation in soybean (Glycine max L.). Therefore, we conducted this study to determine the optimal inoculation density of Bradyhizobium japonicum SAY3-7 (SAY3-7) and Streptomyces griseoflavus P4 (P4) for plant growth, nodulation, and N fixation, and to investigate the effect of co-inoculation on selected soybean cultivars, using the optimal inoculation density. Nitrogen fixation, in terms of an acetylene reduction activity value, was measured using a flame ionization gas chromatograph. In this study, low-density single inoculation with P4 (105 or 106 cells mL-1) was associated with the highest plant biomass, compared with normal- and high-density single inoculation with P4 (107 or 108 cells mL-1). Moreover, low-density single or co-inoculations with SAY3-7 and/or P4 produced the highest nodule biomass and highest nitrogenase activity, compared with single or dual inoculation at other inoculation densities. Therefore, we evaluated low-density co-inoculation with P4 and SAY3-7, at the rate of 105 cells mL-1, on selected soybean cultivars. Low-density co-inoculation increased the plant biomass, compared with un-inoculated plants. The effects of single and co-inoculation on nodulation did not differ significantly for any of the cultivars, except “Yezin-9” in the first experiment and “Shan Seine” in the second experiment. Low-density inoculation with both bacteria increased N fixation by 15% - 75% for seven of the cultivars in the first experiment and by 15% - 39% for three of the cultivars in the second experiment, compared with single inoculation with SAY3-7. Based on the overall results, we concluded that low-density co-inoculation with P4 and SAY3-7 gave improved plant growth and N fixation.