Wojciech Donderski

The occurrence of heterotrophic bacteria decomposing some macromolecular compounds in shallow estuarine lakes

Planktonic bacteria participating in decomposition processes of organic macromolecular compounds were studied in shallow estuarine lakes Lebsko, Gardno and Jamno.The abilities of heterotrophic bacteria to decompose proteins, lipids, starch, nucleic acids, pectin, chitin and cellulose were determined. Characteristic features among the bacteria in the lakes under study were to decompose a wide spectrum of organic macromolecular compounds. Most bacteria hydrolysed proteins, lipids and starch. Pectinolytic and chitinolytic bacteria were less numerous as well as microorganisms able to hydrolyse nucleic acids. The microflora hydrolysing cellulose was represented by the least abundant group of organisms.

Chitinolytic activity of bacteria and fungi isolated from shrimp exoskeletons

Chitinolytic activity of bacteria and fungi isolated from shrimp exoskeletons Microbiological analysis of shrimp exoskeletons demonstrated considerable differences in abundance of heterotrophic bacteria and fungi. The number of heterotrophic bacteria was greater by two orders of magnitude than that of fungi. The survey, however, did not reveal significant differences in abundances of bacteria and fungi in samples collected during different months of the survey. The percent contribution of chitinolytic fungi in shrimp exoskeletons was greater than that of bacteria that hydrolyze chitin. The activity of chitinase bacteria was always higher than fungi. Chitinases produced by bacteria demonstrated the highest level of activity at 40°C and pH = 8. In contrast, fungal chitinases showed the highest activity at 50°C and pH = 5.

Influence of the Root System of the Common Osier (Salix viminalis L.) on Abundance of Heterotrophic Bacteria in the Willow Sewage Treatment System

The impact of the Common Osier (Salix viminalis L.) root system on number (CFU) of heterotrophic bacteria and their production in a soil-willow filter was examined. The Osier rhizosphere was found to be suitable habitat for growth of the examined microbial group, and the root system stimulated development of heterotrophic bacteria. The rhizosphere bacteria to control soil bacteria (R:C) ratio oscillated between 2.48 and 2.75 depending on the location of sample collection. The highest abundance of bacteria as well as highest bacterial production was observed at location I, near sewage discharge onto the plot. There was a significant positive correlation between the number of heterotrophic bacteria and the bacterial production.

Effect of sodium chloride on the metabolic activity of halophilic bacteria isolated from the Lake Gardno estuary

The effect of different concentrations of sodium chloride on the metabolic activity of halophilic bacteria derived from the Lake Gardno estuary was studied using respirometric methods. The influence of salt was examined in two ways: the bacteria were preincubated in various concentrations of sodium chloride, and the cells used for respirometric measurements were supplied with substrates dissolved in water amended with various concentrations of the salt. Generally, an increase in the concentration of sodium chloride in the medium used for preincubation resulted in an increase in metabolic activity. Conversely, a decrease was noted when solutions of increasing salt content were employed to dissolve the substrate. The decrease in oxygen uptake noted when increased amounts of salt were added is proposed to be the result of the short period allowed for adaptation of cells to the higher salt concentrations.

Microbial air contamination on the premises of the sewage treatment plant in Bydgoszcz (Poland) and antibiotic resistance of Staphylococcus spp.

Abstract The study was aimed at evaluating microbial contamination on the premises of the sewage treatment plant by determining the concentrations of selected groups of airborne microorganisms. Another objective was to determine the antibiotic sensitivity patterns of isolated strains of staphylococci. The research was conducted in a seasonal cycle, by the impaction method using Merck MAS-100 air sampler. Samples were collected at six sites, each representing a different stage of sewage treatment. The susceptibility of isolated staphylococci was assessed with the disc-diffusion method, following the recommendations of the EUCAST. The results indicate that the microbial population in the air of the investigated area was dominated by mold fungi, whose highest average concentration was recorded at site IV located near the final clarifier (7672 CFU•m-3). Heterotrophic bacteria and mannitol-positive staphylococci were the most numerous at locations where sewage undergoes primary treatment. In each subseuqent stage the number of microorganisms emitted into the air from the sewage was lower. Antibiograms show that more than 50% of Staphylococcus spp. exhibited resistance to penicillin and 20% to rifampicin. In addition, 90% of the analyzed strains were sensitive to other antibiotics. The fungal community included the following genera: Cladosporium, Fusarium, Alternaria, Penicillium, Aspergillus, Aureobasidium, and Acremonium.The highest air contamination with all studied groups of microorganisms was recorded at the locations where mechanical sewage treatment was performed. During the subsequent stages lower numbers of heterotrophic bacteria were emitted into the air. The air in the investigated sewage treatment plant did not contain multidrug-resistant staphylococci.