Fig. 4

LrhA negatively regulates HA production in P. agglomerans ZJU23. a Inhibition activity of the wild type strain ZJU23, and transposon mutants Tn-1 and Tn-2 against the mycelial growth of F. graminearum. Diameters of inhibition zones were measured after 18 h of co-culture. Each experiment was repeated three times. b The HA production of ZJU23, Tn-1 and Tn-2. c Relative mRNA expression of the HA biosynthetic gene AcbA in ZJU23, mutants and complementation strains. Bacterial cells were harvested after 18 h of incubation and subjected to RNA extraction for quantification of the expression of AcbA by RT-qPCR. The 16S rRNA gene was used as an internal control. The expression in ZJU23 was set as 1.0. Data presented are the mean ± s.e.m. from three biological replicates. Differences between groups were analyzed using Student’s t test (paired, two-sided). *P < 0.05; ****P < 0.0001. d HA production of all tested strains. Strains were grown in HAI medium for 60 h. Data presented are the mean ± s.e.m. from three biological replicates. Differences between groups were analyzed using Student’s t test (paired, two-sided). **P < 0.01; ***P < 0.001; ****P < 0.0001. e Comparison of the HA production of ZJU23 and ΔLrhA fermented using TA, KB or HAI medium. Data presented are the mean ± s.e.m. from three biological replicates. Differences between groups were analyzed using Student’s t test (paired, two-sided). ***P < 0.001; ****P < 0.0001. f–h HPLC–MS quantification of the HA production in ZJU23 and ΔLrhA incubated in TA, KB, HAI medium, respectively