Entropy Production Rate Changes in Lysogeny/Lysis Switch Regulation of Bacteriophage Lambda

According to the chemical kinetic model of lysogeny/lysis switch in Escherichia coli （E. coil） infected by bacteriophage A, the entropy production rates of steady states are calculated. The resuits show that the lysogenic state has lower entropy production rate than lyric state, which provides an explanation on why the lysogenic state of A phage is so stable. We a/so notice that the entropy production rates of both lysogenic state and lyric state are lower than that of saddle-point and bifurcation state, which is consistent with the principle of minimum entropy production for living organism in nonequilibrium stationary state. Subsequently, the relations between CI and Cro degradation rates at two bifurcations and the changes of entropy production rate with CI and Cro degradation are deduced. The theory and method can be used to calculate entropy change in other molecular network.

A Novel Vibriophage vB_VcaS_HC Containing Lysogeny-Related Gene Has Strong Lytic Ability against Pathogenic Bacteria

To avoid the negative effects of antibiotics,using phage to prevent animal disease becomes a promising method in aquaculture.Here,a lytic phage provisionally named vB_Vca S_HC that can infect the pathogen(i.e.,Vibrio campbellii 18)of prawn was isolated.The phage has an isometric head and a non-contractile tail.During phage infection,the induced host mortality in 5.5 h reached ca.96%,with a latent period of 1.5 h and a burst size of 172 PFU/cell.It has an 81,566 bp circular ds DNA genome containing 121 open reading frames(ORFs),and ca.71%of the ORFs are functionally unknown.Comparative genomic and phylogenetic analysis revealed that it is a novel phage belonging to Delepquintavirus,Siphoviridae,Caudovirales.In the phage genome,besides the ordinary genes related to structure assembly and DNA metabolism,there are 10 auxiliary metabolic genes.For the first time,the pyruvate phosphate dikinase(PPDK)gene was found in phages whose product is a key rate-limiting enzyme involving Embden-Meyerhof-Parnas(EMP)reaction.Interestingly,although the phage has a strong bactericidal activity and contains a potential lysogeny related gene,i.e.,the recombinase(Rec A)gene,we did not find the phage turned into a lysogenic state.Meanwhile,the phage genome does not contain any bacterial virulence gene or antimicrobial resistance gene.This study represents the first comprehensive characterization of a lytic V.campbellii phage and indicates that it is a promising candidate for the treatment of V.campbellii infections.