Microbiological and Physico-Chemical Characteristics of Black Tea Kombucha Fermented with a New Zealand Starter Culture.

Kombucha is a popular sparkling sugared tea, fermented by a symbiotic culture of acetic acid bacteria (AAB) and yeast. The demand for kombucha continues to increase worldwide, mainly due to its perceived health benefits and appealing sensory properties. This study isolated and characterised the dominant AAB and yeast from a starter culture and kombucha broth after 0, 1, 3, 5, 7, 9, 11, and 14 days of fermentation at ambient temperature (22 °C).

Role of a local transcription factor in governing cellular carbon/nitrogen homeostasis in Pseudomonas fluorescens.

Autoactivation of two-component systems (TCSs) can increase the sensitivity to signals but inherently cause a delayed response. Here, we describe a unique negative feedback mechanism enabling the global NtrB/NtrC regulator to rapidly respond to nitrogen starvation over the course of histidine utilization (hut) in Pseudomonas fluorescens. NtrBC directly activates transcription of hut genes, but overexpression will produce excess ammonium leading to NtrBC inactivation.

Global Regulatory Roles of the Histidine-Responsive Transcriptional Repressor HutC in Pseudomonas fluorescens SBW25.

HutC is known as a transcriptional repressor specific for histidine utilization () genes in Gram-negative bacteria, including SBW25. However, its precise mode of protein-DNA interactions hasn't been examined with purified HutC proteins. Here, we performed electrophoretic mobility shift assay (EMSA) and DNase I footprinting using His-tagged HutC and biotin-labeled probe of the promoter (P).