Proteases from the marine bacteria in the genus Pseudoalteromonas:diversity,characteristics,ecological roles,and application potentials

Bacterial strains of the genus Pseudoalteromonas,which includes 48 species,are widely distributed in various ocean environments.Many strains are often abundant and the highest protease producer among marine culturable protease-secreting bacteria,suggesting their important role in marine organic nitrogen degradation and cycling.The extracellular proteases of Pseudoalteromonas are diverse,including serine proteases,metalloproteases,and cystine proteases.Pseudoalteromonas proteases have unique properties,such as cold adaptation,salt tolerance,distinct substrate specificity,and catalytic mechanism.They play important ecological roles in marine organic nitrogen degradation and in the interactions of Pseudoalteromonas with other organisms.Some Pseudoalteromonas proteases have shown promising application potentials in bioactive peptide preparation and meat processing.In this review,advances in our knowledge of Pseudoalteromonas proteases are introduced,with a focus on diversity,characters,ecological significance,and application potentials.

Cyanobacterial extracellular alkaline phosphatase:detection and ecological function

Dissolved inorganic phosphorus is an important form of directly bioavailable phosphorus for cyanobacteria in natural water.Dissolved organic phosphorus could be used by cyanobacteria via alkaline phosphatase,which is produced mainly by bacteria and also cyanobacteria itself.Herein,we review the current knowledge of extracellular phosphatase excreted by cyanobacteria,highlighting the development of detection method and its ecological roles in regulating pho sphorus cycling in freshwater systems,which is based on reports for around 100 species of cyanobacteria.Recommendations are suggested concerning the extracellular phosphatase produced by bloom-forming cyanobacteria in terms of the ecological role,followed by a discussion of the future prospects for the study.

Genomic and transcriptomic dissection of Theionarchaea in marine ecosystem

Theionarchaea is a recently described archaeal class within the Euryarchaeota.While it is widely distributed in sediment ecosystems,little is known about its metabolic potential and ecological features.Here,we used metagenomics and metatranscriptomics to characterize 12 theionarchaeal metagenome-assembled genomes,which were further divided into two subgroups,from coastal mangrove sediments of China and seawater columns of the Yap Trench.Genomic analysis revealed that apart from the canonical sulfhydrogenase,Theionarchaea harbor genes encoding heliorhodopsin,group 4[NiFe]-hydrogenase,and flagellin,in which genes for heliorhodopsin and group 4[NiFe]-hydrogenase were transcribed in mangrove sediment.Further,the theionarchaeal substrate spectrum may be broader than previously reported as revealed by metagenomics and metatranscriptomics,and the potential carbon substrates include detrital proteins,hemicellulose,ethanol,and CO_(2).The genes for organic substrate metabolism(mainly detrital protein and amino acid metabolism genes)have relatively higher transcripts in the top sediment layers in mangrove wetlands.In addition,co-occurrence analysis suggested that the degradation of these organic compounds by Theionarchaea might be processed in syntrophy with fermenters(e.g.,Chloroflexi)and methanogens.Collectively,these observations expand the current knowledge of the metabolic potential of Theionarchaea,and shed light on the metabolic strategies and roles of these archaea in the marine ecosystems.