Evaluation of the biocontrol efficacy of Serratia proteamaculans and S. liquefaciens isolated from bats guano pile from a subterrestrial cave (Greece)

Members of the genus Serratia are of great research interest because they are almost ubiquitous and exhibit emulsifying, surfactant, antifouling, antitumor and antimicrobial properties. Water is a natural habitat for several species of serrations. This paper reports on the first isolation of S. proteamaculans from bats guano. The aim of the present study is to evaluate the biocontrol activity of Serratia strains isolated from bats guano pile from a subterrestrial cave of Thessaly region (Aeolia), Greece. Serratia strains initial designated as strains Sl2, Sl4 and were able to ferment glucose (D-glucose), other carbohydrates (i.e. D-mannitol, D-mannose), and saccharose/sucrose as a source of carbon and sugars. Both strains have an optimal growth at 28 °С whereas strain Sl4 were able to grow and at 4 °С. Bacteria strains Sl2 and Sl4 were classified within the Serratia liquefaciens group by the VITEK® 2 system (bioMerieux SA, France) and were accurately identified at the species level by MALDI-TOF MS (bioMerieux SA, France). MALDI-TOF MS classified Sl2 strain as S. proteamaculans and Sl4 strain as S. liquefaciens . To the best of our knowledge, this paper is the first to report the detection and classification in detail of the S. proteamaculans in bat guano. Both Serratia strains produced prodigiosin at 28 °С with optimum prodigiosin production recorded 72 h after incubation. Further the antifungal activity of S. liquefaciens and S. proteamaculans strains were investigated in vitro against plant pathogenic fungi ( Fusarium oxysporum , Alternaria alternata , Botrytis cinerea , Sclerotinia sclerotiorum and Rhizoctonia solani ). This is the first report that S. liquefaciens and S. proteamaculans strains isolated from bat guano were able to produce freely diffusible compounds with fungistatic activity in vitro. Studies on the interaction between pathogen and bacteria confirmed the biocontrol efficacy of both Serratia strains ( S. liquefaciens and S. proteamaculans ).