title: Diversity of protease-producing marine bacteria from sub-antarctic environments.
abstract: From seawater and the intestines of benthonic organisms collected from the Beagle Channel, Argentina, 230 marine bacteria were isolated. Cultivable bacteria were characterized and classified as psychrotolerant, whereas few isolates were psychrophiles. These isolates were capable of producing proteases at 4 and 15 °C under neutral (pH 7.0), alkaline (pH 10.0) and acidic (pH 4.5) conditions on different media, revealing 62, 33 and 22% producers at cold and 84, 47 and 33% producers at low temperatures, respectively. More protease-producing strains (67%) were detected when isolated from benthic invertebrates as compared to seawater (33%), with protease production under neutral conditions resulting in milk protein hydrolysis halos between 27 and 30 ± 2 mm in diameter. Using sterile 0.22 μm membrane filters, 29 isolates exhibiting extracellular protease activity were detected. These were grouped into six operational taxonomic units by restriction analysis and identified based on 16S rDNA as γ-proteobacteria of the genera Pseudoalteromonas, Pseudomonas, Shewanella, Alteromonas, Aeromonas, and Serratia. Plasmids were found to be harbored by eight strains, mainly within the isolates from benthonic organisms.
authors.affiliation: Planta Piloto de Procesos Industriales y Microbiológicos PROIMI, CONICET, Av. Belgrano y Pasaje Caseros, Tucumán, Argentina. hectorcristobal_1@hotmail.com
authors.forename: Héctor Antonio
authors.initials: HA
authors.lastname: Cristóbal
authors.forename: Maria Alejandra
authors.initials: MA
authors.lastname: López
authors.forename: Erika
authors.initials: E
authors.lastname: Kothe
authors.forename: Carlos Mauricio
authors.initials: CM
authors.lastname: Abate
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D001118:Argentina; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D044822:Biodiversity; D016000:Cluster Analysis; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004795:Enzyme Stability; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D007448:Invertebrates; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D010802:Phylogeny; D010957:Plasmids; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D010447:Peptide Hydrolases