Photodynamic　antimicrobial　chemotherapy　(PACT)　is　considered　a　promising　alternative　to　conventional　antibiotic　approach.　We　have　previously　developed　a　novel　PS　containing　five　lysine　amino　acids,　pentalysine-beta-carbonylphthalocyanine　Zinc　(ZnPc(Lys)(5)),　which　in　the　presence　of　light,　is　highly　toxic　against　a　range　of　bacterial　strains,　including　hospital　isolated,　drug　resistant　Acinetobacter　baumannii.　Here,　we　study　the　effect　of　light　fluence　of　the　two　light　sources　on　the　PACT　potency　of　ZnPc(Lys)(5).　We　observed　that　an　exposure　of　E.coli　to　a　red　LED　light　for　only　2　seconds　(light　fluence　of　0.15　J/cm(2))　in　the　presence　of　ZnPc(Lys)(5)　significantly　eradicated　80%　of　the　E.　coli.　We　further　demonstrated　that　a　light　fluence　of　4.5　J/cm(2)　from　a　household　light　source　induced　a　noticeable　photodynamic　effect　in　vitro　and　in　vivo　animal　model.　This　study　points　to　a　new　research　direction　of　reducing　light　illumination　time　by　increasing　potency　of　PS.　(C)　2018　Optical　Society　of　America　under　the　terms　of　the　OSA　Open　Access　Publishing　Agreement