Occurrence of exo- and endopeptidases in dissolved and particulate fractions of coastal seawater

Obayashi, Yumiko; Suzuki, Satoru

doi:10.3354/ame01169

Cited by 47 publications

(55 citation statements)

References 24 publications

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“…In the Day 0 seawater, trypsin and chymotrypsin activities were detected in the < 0.2 µm fraction, while aminopeptidase activity was mainly found in the cellular fraction. These results are in agreement with the studies by Obayashi & Suzuki (2008) and Pantoja et al (1997).Although many reports indicate that the proteolytic potentials in aquatic systems are mainly associated with the bacterial size fraction (e.g. Rosso & Azam 1987), dissolved enzymes can contribute to the total activity.…”

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confidence: 83%

“…Aquat Microb Ecol 69: [33][34][35][36][37][38][39][40][41][42][43][44][45][46] 2013 that associated with bacteria-size particles (Hoppe 1983, Karner & Rassoulzadegan 1995, Pantoja et al 1997, Hoppe et al 2002, Obayashi & Suzuki 2008. Enzyme activity intensifies in suspended and sinking organic aggregates (Smith et al 1992, Taylor et al 2009).…”

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confidence: 99%

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Succession of protease activity in seawater and bacterial isolates during starvation in a mesocosm experiment

Bong¹,

Obayashi²

2013

Aquat. Microb. Ecol.

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Protein biodegradation in the marine environment is caused by proteases derived from various organisms, including bacteria, which are considered to be a major source of these enzymes. We investigated the succession of bacterial proteases in seawater to determine the variation in protease activity over time. The potential activities of proteolytic enzymes in stored seawater and isolated bacteria were studied using 19 different synthetic oligopeptide substrates for aminopeptidase, trypsin, chymotrypsin and elastase. In time-course experiments carried out over 112 d, aminopeptidase activity increased, whereas trypsin activity decreased over time. Aminopeptidase activity was mainly found in unfiltered seawater containing bacterial cells, whereas trypsin activity was mainly found in 0.2 µm seawater filtrates. Individual bacterial isolates showed different proteolytic properties but all exhibited aminopeptidase activity. Members of the Gammaproteobacteria and Bacteroidetes showed high trypsin and chymotrypsin activities. Based on these results, we conclude that protein degradation in seawater occurs via the combined action of various bacterial proteases.KEY WORDS: Bacterial protease · Aminopeptidase · Trypsin · Cell-associated enzymes · Dissolved fraction · Seawater Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 69: [33][34][35][36][37][38][39][40][41][42][43][44][45][46] 2013 that associated with bacteria-size particles (Hoppe 1983, Karner & Rassoulzadegan 1995, Pantoja et al. 1997, Hoppe et al. 2002, Obayashi & Suzuki 2008. Enzyme activity intensifies in suspended and sinking organic aggregates (Smith et al. 1992, Taylor et al. 2009). Furthermore, culture supernatants of marine bacteria contain many types of proteases (Oda gami et al. 1994), indicating that bacteria release proteases into the en vironment. Sequential degradation of proteins by the combined action of various proteases is believed to occur in aquatic ecosystems. However, the specific bacterial groups responsible for protein degradation in seawater are still unknown. Therefore, the origin of proteolytic enzymes in seawater and the contribution of various groups of bacteria to the pool of proteolytic enzymes are of interest.In this study, we examined the changes in proteolytic activity on several protein substrate analogues due to starvation in a long-term microcosm. Enzymes from isolated bacteria were also characterized to evaluate their potential role in protein degradation in the aquatic ecosystem. MATERIALS AND METHODS SamplingSurface seawater samples were collected from the Matsuyama coast, Ehime Prefecture, Japan (33°54' 23.9'' N, 132°34.2' E), in January 2009. The surface seawater temperature and salinity were 13°C and 35, respectively. The monthly profile of proteolytic activity at the sampling site has been reported by Obayashi & Suzuki (2005). Seawater was pre-filtered through a 150 µm plankton net and kept cold until it was processed within 2 to 3 h. The seawater sample used for t...

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confidence: 83%

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Succession of protease activity in seawater and bacterial isolates during starvation in a mesocosm experiment

Bong¹,

Obayashi²

2013

Aquat. Microb. Ecol.

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“…However, with few efforts to study the effect of grazers on protein hydrolysis (Pérez et al, 2003;Kawasaki and Benner, 2006), the role of proteolytic enzymes in protein degradation in communities composed of both bacteria and protists is poorly understood. Previous studies have sought to determine the role of microbial enzymes in the protein degradation process in seawater (Suzuki et al, 1997(Suzuki et al, , 1999Obayashi and Suzuki, 2008). Here, we expand on previous research by examining the role of protists as well through monitoring of both enzyme activity and substrate fate in seawater microcosms.…”

Section: Introductionmentioning

confidence: 88%

“…Arnosti et al (2011), suggested that in seawater the diversity of enzymes that degrade complex substrates is positively correlated with the diversity of the microbial community. Obayashi and Suzuki (2008), also reported that each bacterial isolate shows substrate specificity, whereas a variety of substrates are hydrolyzed by the natural bacterial community in bulk seawater. Hence, the greater variety of microorganisms and their respective capability to degrade organic matter might have made the community in the SW-0.7+Pa microcosm more active and robust.…”

Section: Discussionmentioning

confidence: 99%

Coexisting protist-bacterial community accelerates protein transformation in microcosm experiments

2014

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Proteins constitute the major portion of labile substances in the marine environment and are an important source of organic matter supporting marine ecosystems. However, previous studies have revealed that specific bacterial membrane proteins are refractory in the oceans. We here show by kinetic analyses of protease degradation activity using inactivated Pseudomonas aeruginosa (Pa) cells as a proteinaceous substrate that bacterial proteases are insufficient to completely hydrolyze proteins, which may partially cause the protein accumulation in seawater. Protease activity was monitored simultaneously in 8 microcosms subjected to differing conditions. Some Pa proteins were retained for 30 days in the presence of bacteria without protists, whereas the Pa proteins were completely disappeared in the presence of both, indicating that these proteins were substantially incorporated into protist biomass. Our result suggests that protists play an important role in the transformation of bacterial proteins in seawater. Our experiments also imply that the functional/taxonomic diversity should be taken into account when considering decomposition activity in marine environments.

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“…Laboratory experiments show that pure cultures of marine bacteria release enzymes into the surrounding media (Vetter and Deming, 1999;Alderkamp et al, 2007). High levels of dissolved endopeptidase activity in coastal seawater (Obayashi and Suzuki, 2008) also underscore the importance of cell-free enzymes in the ocean. The relative contributions of cell-free enzymes to total hydrolytic activity varies among enzymes; for example, contributions of dissolved laminarinase and xylanase to total hydrolytic activities were found to vary with site and season in a riverine-marine transect (Keith and Arnosti, 2001), and varied temporally during the course of a mesocosm bloom (Murray et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Changes in the spectrum and rates of extracellular enzyme activities in seawater following aggregate formation

2010

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Abstract. Marine snow aggregates are heavily colonized by heterotrophic microorganisms that express high levels of hydrolytic activities, making aggregates hotspots for carbon remineralization in the ocean. To assess how aggregate formation influences the ability of seawater microbial communities to access organic carbon, we compared hydrolysis rates of six polysaccharides in coastal seawater after aggregates had been formed (via incubation on a roller table) with hydrolysis rates in seawater from the same site that had not incubated on a roller table (referred to as whole seawater). Hydrolysis rates in the aggregates themselves were up to three orders of magnitude higher on a volume basis than in whole seawater. The enhancement of enzyme activity in aggregates relative to whole seawater differed by substrate, suggesting that the enhancement was under cellular control, rather than due to factors such as lysis or grazing. A comparison of hydrolysis rates in whole seawater with those in aggregatefree seawater, i.e. the fraction of water from the roller bottles that did not contain aggregates, demonstrated a nuanced microbial response to aggregate formation. Activities of laminarinase and xylanase enzymes in aggregate-free seawater were higher than in whole seawater, while activities of chondroitin, fucoidan, and arabinogalactan hydrolyzing enzymes were lower than in whole seawater. These data suggest that aggregate formation enhanced production of laminarinase and xylanase enzymes, and the enhancement also affected the surrounding seawater. Decreased activities of chondroitin, fucoidan, and arabinoglactan-hydrolyzing enzymes in aggregate-free seawaters relative to whole seawater are likely due to shifts in enzyme production by the aggregateCorrespondence to: K. Ziervogel (ziervoge@email.unc.edu) associated community, coupled with the effects of enzyme degradation. Enhanced activities of laminarin-and xylanhydrolyzing enzymes in aggregate-free seawater were due at least in part to cell-free enzymes. Measurements of enzyme lifetime using commercial enzymes suggest that hydrolytic cell-free enzymes may be active over timescales of days to weeks. Considering water residence times of up to 10 days in the investigation area (Apalachicola Bay), enzymes released from aggregates may be active over timescales long enough to affect carbon cycling in the Bay as well as in the adjacent Gulf of Mexico. Aggregate formation may thus be an important mechanism shaping the spectrum of enzymes active in the ocean, stimulating production of cell-free enzymes and leading to spatial and temporal decoupling of enzyme activity from the microorganisms that produced them.

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Occurrence of exo- and endopeptidases in dissolved and particulate fractions of coastal seawater

Cited by 47 publications

References 24 publications

Succession of protease activity in seawater and bacterial isolates during starvation in a mesocosm experiment

Succession of protease activity in seawater and bacterial isolates during starvation in a mesocosm experiment

Coexisting protist-bacterial community accelerates protein transformation in microcosm experiments

Changes in the spectrum and rates of extracellular enzyme activities in seawater following aggregate formation

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