Miroslav M. Vrvić's research while affiliated with Institute for Educational Research, Belgrade, Serbia and other places

The use of fossil fuels leads to environmental contamination during their extraction, processing and distribution. Microbial biodegradation provides a sustainable method for cleaning contaminated areas which follows the principles of sustainability. This paper presents the dynamics of biodegradation of hydrocarbon fractions of diesel oil, using Planomicrobium sp. and Rhodococcus sp. isolated from petroleum-contaminated sites. GC–MS analysis was employed to analyse abundances of the specific compounds such as n-alkanes, isoprenoids, sesquitepranes, hopanes, steranes and aromatic compounds (naphthalene and its methylated homologues, phenanthrene and anthracene and their methylated homologues, and dibenzothiophene and its methylated homologues). The obtained results showed that after 30 days of biodegradation of diesel, a significant degradation was achieved, with almost complete degradation of n-alkanes and a decrease in the amount of sesquiterapanes. Rhodococcus sp. had a higher efficiency in degradation of n-alkanes, while Planomicrobium sp. had a higher efficiency in the degradation of branched hydrocarbons. Both strains showed high activity in the biodegradation of sesquitepranes and demonstrate ability to degrade methylated phenanthrenes. Additionally, dimethyl-dibenzothiophenes were almost completely degraded and removed from the system. This study presents the first comprehensive report on the GC–MS analysis of the diesel biodegradation pattern of the Planomicrobium sp., compared with the well-established Rhodococcus sp.

Human milk is a biofluid with a unique composition among mammalian milks. Besides this milk’s major components, its bioactive compounds, like hormones, immune factors, and oligosaccharides, are unique and important for infant growth and development. The best form of nutrition for term and preterm infants is the mother’s own milk. However, in the absence of the mother’s own milk, donor milk should be made available. Milk banks support neonatal intensive care units by providing preterm infants with human milk that generally has reasonable nutritive value for this sensitive population. However, neither mother’s own milk nor donor milk has sufficient energy content for the growth of preterm babies, so adequate human milk supplementation is crucial for their progress. Due to the different characteristics of human breast milk, as well as ubiquitous environmental pollutants, such as microplastics, new methods are required for monitoring the quality and characteristics of human milk, which will lay a solid foundation for the further development and progress of human milk research.

The aim of this paper is to provide insight into research and activities of in situ remediation to remove petroleum hydrocarbon pollutants from a contaminated aquifer’s sediment, located near two radial collector wells of a water supply system. It was decided that the most appropriate method for remediation of this aquifer’s sediment is in situ bioremediation because it is clean, efficient and sustainable technology. Before the start of the bioremediation process, it was necessary to isolate and cultivate the microorganisms present at the contamination site, so they could be later applied in the bioremediation process. The samples before and after the bioremediation were studied using both GC and GC × GC–MS to determine how the concentrations of contaminants changed over time. Additionally, in this paper, a spatiotemporal representation of the change in hydrocarbon content by depth within the zone of the highest contamination over time is shown. After 12 months of bioremediation, the hydrocarbon content in the samples decreased by 82.0%, and based on GCxGC-MS analysis, the order of degradation of various hydrocarbon groups was as follows: steranes (99.6%), isoprenoids (98.4%), benzene derivatives (98.4%), alkanes (97.2%), and terpenes (49.3%). The exponential decay model showed the greatest decomposition rate of hydrocarbons occurred at depths of 8–10 m, with an average decay constant of 0.227, independent of the initial concentration of hydrocarbons. To the best of our knowledge, to date, the described approach has not been applied to an aquifer (the simultaneous treatment of groundwater and its associated sediment layers). Graphical abstract