Algicidal Activity and Microcystin-LR Destruction by a Novel Strain Penicillium sp. GF3 Isolated from the Gulf of Finland (Baltic Sea).

The present article focuses on a strain of ascomycete GF3 isolated from a water sample taken in the Gulf of Finland. Based on phylogenetic analysis data, the isolate was identified as Penicillium sp. GF3. The fungus GF3 demonstrates algicidal activity towards cyanobacteria (98-100%). The algicidal effect on green algae did not exceed 50%. The isolate GF3 exhibits an indirect attack mode by releasing metabolites with algicidal and/or lytic activity into the environment. Moreover, the strain Penicillium sp. GF3 is able to degrade MC-LR. After 72 h of GF3 cultivation, the MC-LR content was reduced by 34.1% and 26.7% at initial 0.1 µg/mL and 0.45 µg/mL concentrations, respectively. The high stress resistance of the GF3 to toxic MC-LR is provided by a 1.5-fold activation of catalase activity and a change in the reduced glutathione content. Additionally, during the MC-LR biotransformation, a MC-LR-GSH conjugate and linearized MC-LR were identified. The linearized MC-LR in the presence of fungi capable of degrading MCs was revealed for the first time. Using Daphnia magna as a bioindicator, it was shown that the MC-LR biotransformation led to the formation of less toxic intermediates. The toxicity of the fungal filtrate is reduced by five times compared to the abiotic control. Our findings enhance the understanding of the role that ascomycete fungi have as potential bioagents for cyanoHABs to control and detoxify water bodies.

A microcosm approach for evaluating the microbial nonylphenol and butyltin biodegradation and bacterial community shifts in co-contaminated bottom sediments from the Gulf of Finland, the Baltic Sea.

Pollution of aquatic ecosystems with nonylphenol (NP) and butyltins (BuTs) is of great concern due to their effects on endocrine activity, toxicity to aquatic organisms, and extended persistence in sediments. The impact of contamination with NP and/or BuTs on the microbial community structure in marine sediments was investigated using microcosms and high-throughput sequencing. Sediment microcosms with NP (300 mg/kg) and/or BuTs (95 mg/kg) were constructed. Complete removal of monobutyltin (MBT) occurred in the microcosms after 240 days of incubation, while a residual NP rate was 40%. The content of toxic tributyltin (TBT) and dibutyltin (DBT) in the sediments did not change notably. Co-contamination of the sediments with NP and BuTs did not affect the processes of their degradation. The pollutants in the microcosms could have been biodegraded by autochthonous microorganisms. Significantly different and less diverse bacterial communities were observed in the contaminated sediments compared to non-contaminated control. Firmicutes and Gammaproteobacteria dominated in the NP treatment, Actinobacteria and Alphaproteobacteria in the BuT treatment, and Gammaproteobacteria, Alphaproteobacteria, Firmicutes, and Acidobacteria in the NP-BuT mixture treatment. The prevalence of microorganisms from the bacterial genera Halothiobacillus, Geothrix, Methanosarcina, Dyella, Parvibaculum, Pseudomonas, Proteiniclasticum, and bacteria affiliated with the order Rhizobiales may indicate their role in biodegradation of NP and BuTs in the co-contaminated sediments. This study can provide some new insights towards NP and BuT biodegradation and microbial ecology in NP-BuT co-contaminated environment.

Environmental hazards of sea-dumped chemical weapons.

Does the post-WWII burial at sea of chemical weapons still pose a human and environmental risk?

Microbial responses to mustard gas dumped in the Baltic Sea.

Microbiological studies were carried out on chemical weapon dump sites in the Baltic Sea. The effect of mustard gas hydrolysis products (MGHPs) on marine microbiota and the ability of microorganisms to degrade MGHPs were studied. Many stations at the dump sites demonstrated reduced microbial diversity, and increased growth of species able to use mustard gas hydrolysis products as sole source of carbon. Significant amounts of MGHP-degrading bacteria were revealed in the near-bottom water. The MGHP-degrading microorganisms identified as Achromobacter sp., Pseudomonas sp., and Arthrobacter sp. were isolated. These microorganisms were capable of utilizing the major product of hydrolysis, thiodiglycol, as the sole source of carbon and energy. The bacteria were capable of metabolizing MGHPs at a low temperature. The metabolic pathway for thiodiglycol degradation was proposed. The results suggest the potential for MGHPs biodegradation by naturally occurring populations of near-bottom-water and sediment microorganisms.

Soil bacterium Pseudomonas sp.: destroyer of mustard gas hydrolysis products.

A bacterial culture capable of utilizing products of mustard gas hydrolysis as a source of carbon was isolated from soil. This culture was tolerant to organochlorine substances in the hydrolysate. The bacterium was identified as Pseudomonas sp. The bacterium utilizes the major product of mustard gas hydrolysis, thiodiglycol, through two pathways. One involves the oxidation of the primary alcoholic groups in thiodiglycol, yielding thiodiglycolic and thioglycolic acids. The cleavage of the C-S bonds in these acids gives rise to acetate, which is then used further in the cell metabolism. The other pathway involves the cleavage of the C-S bond in the thiodiglycol molecule, yielding beta-mercaptoethanol, which is transformed by Pseudomonas sp. into thioglycolic acid. The results show the promise of this bacterium for the bioremediation of mustard gas-contaminated soils.