bacteria bacterialphysiologicalphenomena cells congresses cytology development escherichiacoli feeds food growth metabolism microbialdifferentiation microbialmetabolism microbiologicalchemistry microbiology molecularbiology peptidoglycan peptidoglycans physiology qw51i54g1983 qw52b130671993 qw52b61251982 qw52d993d1985 qw52m7181984 water