Martinovs, Andris

2017, Tretjakova, Rasma, Lazov, Lyubomir, Martinovs, Andris, Samanta Marija Misiņa

At the biogas plant total of 40 digestate samples have been collected and investigated. The microbiological composition of digestate has been analysed before and after laser processing with wavelength λ 445 nm with power 2 - 4 W. Salmonella spp. has not been stated in any of the samples, Escherichia coli and Enterococcus spp. amount does not correspond Eiropean Union regulation R142/2011 requirements in any of the investigated samples; Staphylococcus aureus has been stated in 24 samples out of 40. By decreasing laser scanning speed and increasing power, the total number of microorganism colonies in digestate has decreased.

2015, Tretjakova, Rasma, Jūlija Grebeža, Martinovs, Andris

Microbiological characteristics of dried sapropel of Lake Rušona and Lake Ubagova and concrete containing sapropel and hemp sheaves (Ubagova Lake) have been studied. The antimicrobial activity was studied by the Staphylococcus aureus  ATCC 25923, Salmonella enteritidis ATCC 13076, Enterococcus faecalis  ATCC 29212, Bacillus cereus  ATCC 10876, Escherichia coli ATCC 25922, Candida albicans ATCC 10231. Antibacterial activity on reference test cultures is stated in Rušona Lake sample before treatment with UV rays. Antibacterial activity is not stated in Ubagova Lake sapropel sample. 20 minutes’ long UV ray treatment is not long enough to prevent the growth of sapropel materials. Both Rušona Lake and Ubagova Lake samples contain microorganisms that start growing and intensively reproducing in favourable conditions. When in contact with humidity, at the temperature from 18 to 37± 1C, mold colonies form on concrete containing sapropel and hemp sheaves, for this reason this material should not get in contact with humidity when used in construction.