Current perspectives on the remediation methods of marine plastic pollution: a review

Plastic debris represents a contemporary point of concern for the marine environment, being discharged into the ocean at an alarming scale. However, the quantity of waste that is found in the ocean is unknown. Where does this waste come from, and where does it end up are questions that scientists and researchers are still trying to accurately answer. The majority of plastic products that make their way into the ocean come mainly from human activities. Most of them land on beaches, and eventually find their way into the ocean, being washed away by waves and tides. To assess the impact of these pollutants that are found in the marine environment, it is necessary to determine the concentration of the chemicals accumulating in the biomass, and the effects they cause. There are numerous biological effects which lead to many obvious diseases in marine species. Also, these harmful effects determine changes in community structure, the modification of the habitat and local or complete extinction of many aquatic species. This review aims to lay out the present situation of the marine environment, and the effects of the pollution caused by industrialization and urbanization. Different types of remediation approaches have been discussed, such as physical remediation techniques. Besides that, the role of numerous bacteria and fungi that are capable of breaking down these chemicals that surround us, has been highlighted and point at some of the bioremediation technologies that are currently available. Lup et al (PDF) Article history: Received 26 September 2020; Revised 20 November 2020; Accepted 3 December 2020; Available online 20 December 2020. &nbsp

Correlation between CRISPR Loci Diversity in Three Enterobacterial Taxa

CRISPR-Cas is an adaptive immunity system of prokaryotes, composed of CRISPR arrays and the associated proteins. The successive addition of spacer sequences in the CRISPR array has made the system a valuable molecular marker, with multiple applications. Due to the high degree of polymorphism of the CRISPR loci, their comparison in bacteria from various sources may provide insights into the evolution and spread of the CRISPR-Cas systems. The aim of this study was to establish a correlation between the enterobacterial CRISPR loci, the sequence of direct repeats (DR), and the number of spacer units, along with the geographical origin and collection source. For this purpose, 3474 genomes containing CRISPR loci from the CRISPRCasdb of Salmonella enterica, Escherichia coli, and Klebsiella pneumoniae were analyzed, and the information regarding the isolates was recorded from the NCBI database. The most prevalent was the I-E CRISPR-Cas system in all three studied taxa. E. coli also presents the I-F type, but in a much lesser percentage. The systems found in K. pneumoniae can be classified into I-E and I-E*. The I-E and I-F systems have two CRISPR loci, while I-E* has only one locus upstream of the Cas cluster. PCR primers have been developed in this study for each CRISPR locus. Distinct clustering was not evident, but statistically significant relationships occurred between the different CRISPR loci and the number of spacer units. For each of the queried taxa, the number of spacers was significantly different (p < 0.01) by origin (Africa, Asia, Australia and Oceania, Europe, North America, and South America) but was not linked to the isolation source type (human, animal, plant, food, or laboratory strains)