Taxonomy and Depth Distribution of Proteolytic Bacteria Isolated from Water of the Rio Grande Rise Region, South Atlantic

TAXONOMY AND DEPTH DISTRIBUTION OF PROTEOLYTIC BACTERIA ISOLATED FROM WATER OF THE RIO GRANDE RISE REGION, SOUTH ATLANTIC

da Silva, M. A. C.1*; Verdegal, R. O.1; Zirke, B.1; Delabary, G. S.1; da Veiga, C. H.1; Lima, A. O. S.1. 1Centro Tecnológico da Terra e do Mar, Universidade do Vale do Itajaí, Santa Catarina, Brasil. *e-mail: [email protected]

Proteases are hydrolytic enzymes that act on peptides and are important for the normal functioning of cells. These molecules are widely distributed in marine bacteria, including intracellular and extracellular types. Besides their biological importance for the bacterial cell, proteases can also be biotechnologically applied to wastewater treatment, to the production of detergents and animal feed. Several marine bacteria are reported as capable of producing proteases, including strains isolated from different depths of oceanic regions. In this context, the present work aimed to analyze the taxonomic composition and depth distribution of proteolytic bacteria from water samples of the Rio Grande Rise Region, South Atlantic. One hundred and four strains of marine bacteria were tested in triplicates for their proteolytic activity on marine agar plates supplemented with skim milk. Twenty-four percent of the strains tested were proteolytic. The frequency of proteolytic bacteria was higher at the thermocline zone, followed by the maximum depth zone (at the bottom of the water column). These are zones with higher organic matter concentration, as a function of the primary production (at the thermocline) and the influence of sedimentary organic matter (at the maximum depth), which could explain this distribution pattern. The lowest frequency of proteolytic bacteria was observed at the limit of the euphotic zone. The proteolytic bacteria belonged to nine different species of five bacterial classes. The class Bacilli was the best represented among the proteolytic bacteria, with five strains belonging to the species Bacillus stratosphericus. Gammaproteobacteria was represented by three strains of Pseudoalteromonas mariniglutinosa, and Flavobacteriia included three strains of Zunongwangia profunda. The other species were represented by a single strain each and include the classes Alphaproteobacteria and Actinobacteria. The strain Salinicola salarius LAMA 918 was the most active among the bacteria tested. These results indicate that proteolytic bacteria are diverse and are not equally distributed in marine pelagic environments.

Palavras-chaves: Proteolytic bacteria, South Atlantic Ocean, depth distribution. Área de conhecimento: Microbiologia Ambiental e Agrícola