Browsing by Author "Mäkinen, Taru-Marja"

Antibiotic resistance is a global threat which could lead us into a “post-antibiotic” era. Although antibiotic resistance is a natural and ancient phenomenon, the widespread use of antibiotics has accelerated the evolutive selective pressure for antibiotic-resistant bacteria and antibiotic-resistant genes (ARGs). The EU is promoting using of bio-based fertilizers (BBFs) due to sustainability goals, yet these are materials that may contain bacteria carrying ARGs as well as antibiotic-producers such as Streptomyces. The role of antibiotic-producing bacteria in the dissemination of antibiotic resistance has not been extensively studied and therefore it is not fully understood. This work aimed to investigate phenotypic and genotypic characteristics of eight bacterial isolates from two different BBFs, which were composted biosolids, to gain a preliminary understanding of the role of antibiotic producers as potential mediators of the resistance. The phenotypic characteristics of isolates were studied using various media and temperatures. Whole-genome sequencing and bioinformatic approaches were used to investigate the genotypic features. One isolate from an ancient latrine, sampled during archeological excavation, was included in the bioinformatic analyzes to be compared with the genotypic similarity of the modern isolates. The phenotypic characteristics of the isolates were typical of Streptomyces, such as the formation, color, and composition of aerial and substrate mycelium. According to bioinformatic tools used (GTDB, ResFinder, MGE, and antiSMASH databases and BLASTn), the isolates were identified as Streptomyces spp. Several ARGs were found in the isolates: a total of 11 types of beta-lactam, 4 types of aminoglycoside, 5 types of glycopeptide, 7 types of macrolide, 4 types of phenicol, 2 types of quinolones, and 9 types of tetracycline resistance genes passed the qualitative screening. Ten different mobile genetic element (MGE) components were also found in the isolates. In addition, from 15 to 29 potential clusters of secondary metabolites were identified in the genomes of the isolates, some of which are known to have antibiotic activity. The results of this study suggest that antibiotic producers might play a role in maintaining and possibly even transmitting resistance genes in composted biosolids. Although this was only a preliminary and limited study on this topic, it suggests that antibiotic producers may have contributed to the dissemination and evolution of antibiotic resistance. Thus, investigating the co-evolution of antibiotic producers and antimicrobial resistant bacteria should be in the interest of scientists from here on. Perhaps understanding the interactions of the producers and resistant bacteria could open new pathways for controlling the spread of antibiotic resistance.