Browsing by Subject "mikrobi"

This study was conducted to find suitable methods for the quality control of commercial plant growth-promoting (PGP) microbial products. A commercial bacterial product called TwinN was evaluated for its microbiological quality, physiological features of its bacterial strains, and its ability to promote plant growth. Other bacterial strains which had shown PGP features in earlier studies, were used as reference strains. The microbiological composition of the TwinN bacterial lyophilisate corresponded to the manufacturer's description, as it was composed of bacteria belonging to the genera Azoarcus, Azorhizobium, and Azospirillum. However, the concentrations of some of the bacterial species were lower than reported. If the product was used according to the manufacturer's instructions, the bacterial counts in the plants wouldn't necessarily reach a sufficient level. With the TwinN product, a powdery growth medium was also supplied, which appeared to be highly contaminated with bacteria and moulds. The nature and source of these microbes remained unknown. The bacteria in the TwinN product were isolated as pure cultures, and identified based on the partial sequences of their 16S rRNA genes. Specific plate and broth culturing techniques were used to uncover the potential PGP physiological features of the pure cultures. The bacterial strains were able to produce indole-3-acetic acid, ACC deaminase and siderophore, which suggests that they might also have PGP activity. The ability of the bacteria to promote plant growth was tested in a plant experiment using hydroponic growth pouches. An Azospirillum brasilense strain isolated from the TwinN product was able to increase the dry weight of the shoots of chinese gabbage almost 41 % compared with the uninoculated control plants. Of the five bacterial treatments used, the A. brasilense strain was the only one able to promote plant growth. Chinese cabbage was the only plant species out of six that gave a positive response to the A. brasilense treatment. For some reason, the TwinN product itself didn't show any PGP activity. The plants showed signs of nitrogen deficiency, which indicates that no bacterial nitrogen fixation had taken place. The method used to determine the microbial composition of the TwinN product, was Amplicon sequencing. Combined with the results of traditional culturing techniques, Amplicon sequencing proved to be a useful method for the assessment of the microbiological quality of the product. The physiological tests that could be of use in the quality control of PGP products, are siderophore production test, phosphate solubilization test and the test that measures indole-3-acetic acid production.

Abstract This work was done at R&D Center of Kemira Oy in Espoo. Paper machines are open systems which are impossible to keep sterile. Paper machines offer favourable conditions for microbial growth. Microbiological problems in paper industry have been reported for years and expanding the production facilities and recycling of process waters have increased microbial growth. Microorganisms cause a lot of problems in paper machines and contaminatios can lead to huge economical loses. Biofilms can block filters and nozzles. Biofilms cause production breakdowns. The quality of produced paper is deteriorated, produced paper can have holes and discalourations. Sometimes the paper machine has to be stopped. Biofilms also increase the corrosion of machinery. Biocides are commonly used to control the formation of biofilms. Biocides are dosed with process waters and they are not specific to biofilm forming bacteria. Biofilms tolerate biocides better than planktonic bacteria and the biofilm problem has not been able to solve. There are a lot of different microbes found on paper making processes. Paper machines can contain viruses, bacteria, syanobacteria, molds, yeasts, algae ja protozoa. Paper machines environment and location, temperature, pH, raw materials and other additives have impact on the composition of microbe population. Kemira has a targeted-release biocide product on the market. Polymeric micelles protect biocidal active agents from degradation while it has been delivered to the targeted surfaces. Global patent has been applied for this targeted-release technology. Target of this work was to develop a cheaper version of this product having same targeted effects and better storage stability In this work the stability, efficacy against planktonic cells and against biofilm were tested. qPCR and sequencing were used to test the effect of the biocide to microbe population.

Immune-mediated diseases, such as various allergies and asthma, are increasing rapidly in an urbanized world where biodiversity is steadily declining. Decreased biodiversity and homogenous microbiota have been associated with weaker immune defence. Studies show that contact with the natural environment enriches the human microbiota, promotes immune response, and protects against allergies and inflammatory diseases. For this reason, in order to prevent immune-mediated diseases, solutions have been sought from nature-based approaches in which the immune system encounters environmental microbial stimuli in a natural way. The aim of this master's thesis was to study how different nature-based materials (sod and forest floor) affect the skin microbiota of kindergarten-age children and to examine how different factors such as varying weather conditions and different sampling times affect the results. The results supported the hygiene hypothesis and previous research according to which increasing biodiversity can have a positive effect on human skin microbial communities. A positive effect on children's skin was achieved with sod alone, which is important information in the development of suitable biodiverse materials for urban planning. The results also supported the surmise that different weather conditions and sampling methods can significantly affect the results.