2026-09-18T22:26:29Zhttps://helda.helsinki.fi/server/oai/request

oai:helda.helsinki.fi:10138/3226072026-03-27T00:31:32Zcom_10138_18086com_10138_17738col_10138_18088

Helsingin yliopisto, Bio- ja ympäristötieteellinen tiedekunta, Bio- ja ympäristötieteellinen tiedekunta University of Helsinki, Faculty of Biological and Environmental Sciences, Faculty of Biological and Environmental Sciences Helsingfors universitet, Bio- och miljövetenskapliga fakulteten, Bio- och miljövetenskapliga fakulteten Avila Pulido, Alan Auvinen, Petri Ylinen, Anne 2020 URN:NBN:fi:hulib-202012094855 http://hdl.handle.net/10138/322607 Psychrotrophic lactic acid bacteria (LAB) play a versatile role in research, food, farming and medicinal applications, but also play a role as a source of food spoilage. The effects of temperature changes has yet to be studied in depth. In this study, to analyze in a transcriptome level, cold and heat shock stress to spoilage lactic acid bacteria, a time-dependent RNA-seq for Lactococcus piscium with a temperature of 0 °C and 28 °C was conducted. The data of protein regulation during the experiment shows that Lactococcus piscium has the essential machinery to survive against different types of environmental stress. I observed known heat shock related genes and stress related genes to be present in the regulated response of both temperature extremes. Cold shock upregulation is observed after 35 minutes, which could indicate that the metabolic response at cold temperatures is related to growth rate. With a clear downregulation of pathways of energy consumption and an adaptation in terms of RNA being more prominent that at 28 ºC. Certain surface, cell wall and transport proteins are noticeable more upregulated at 0 ºC in addition to a downregulation of energy related proteins, which in correlation with its growth curve, we can assume it is part of a mechanism of protection against cold environments, in comparison with the regulation of proteins at 28 ºC. This gives an insight of a well controlled preservation mechanism that Lactococcus piscium exhibits that can be linked to its environment. The findings of this research offer new understandings into the survival skills of Lactococcus piscium to a cold and heat shock. Future studies should focus on analyzing the regulation and function of possible new genes for the response to heat stress, as well as the specific function of proteins related to temperature stress in the events where change of temperature plays a constant role in the environment. eng Helsingin yliopisto University of Helsinki Helsingfors universitet RNA-seq rRNA removal differential gene expression stress psychrotrophic lactic acid bacteria Lactococcus piscium cold and heat shock temperature shock biotekniikka Biotechnology bioteknik Transcriptomic analysis of the response of the lactic acid bacteria Lactococcus piscium for the identification of possible adaptive genes during thermal shock in cold and warm temperatures pro gradu -tutkielmat master's thesis pro gradu-avhandlingar URN:NBN:fi:hulib-202012094855 open.access