Faculty of Agriculture and Forestry

The market potential of meat analogs is increasing widely due to the global shift towards reduced meat consumption. High-moisture extrusion processing (HMEP) is well-known for creating plant-based meat analogs with fibrous structure. However, plant proteins such as faba bean protein concentrate (Faba-C) which have poor/moderate structure forming ability, and less explored plant proteins such as chickpea protein concentrate (Chic-C), require further attention. L-cysteine, when added at optimized concentrations, can enhance the fibrous structure formation by altering the protein-protein interactions during HMEP. Thus, this study aimed to investigate the effect of L-cysteine on the fibrous structure formation of Faba-C and Chic-C. The hypothesis was that L-cysteine would improve the fibrous structure of these proteins through its effect on protein-protein interactions. To interpret the effect on fibrous structure formation, various concentrations ranging from 0.05% to 0.4% of L-cysteine were examined. From these, chosen concentrations of L-cysteine added samples were further investigated for their characteristics by mechanical strength tests (such as cutting strength and tensile strength), physicochemical properties (such as protein solubility, protein profile, and surface hydrophobicity), and protein-protein interactions (such as free thiol groups and protein conformational changes) studies. On a visual appearance, the addition of 0.05% and 0.1% of L-cysteine did not lead to the formation of new fibrils in Faba-C but led to a slightly sharper angle at 0.1% of L-cysteine addition in Chic-C extrudates. At higher concentrations, the extrudates started to lose their fibrous structure. For further analysis, 0.05% and 0.1% of L-cysteine were chosen as optimal samples. Additionally, 0.4% of L-cysteine was studied to interpret its impact in Faba-C and Chic-C extrudates. Results showed that 0.4% of L-cysteine led to low cutting (Chic-C) and tensile strength which was consistent with the loss of fibrous structure. The solubility of proteins did not vary notably, and the protein profile remained unchanged in all the L-cysteine concentrations. The surface hydrophobicity of 0.4% of L-cysteine increased in Faba-C extrudates. Excessive free thiol groups were obtained at 0.4% of L-cysteine in both Faba-C and Chic-C indicating that L-cysteine could have altered the protein-protein interactions during HMEP. Protein conformational changes at 0.05%, 0.1%, and 0.4% of L-cysteine in Chic-C occurred indicating that L-cysteine has altered the structure formation even at low concentrations whose effects were not visible effectively on the macrostructure. Thus, it can be concluded that L-cysteine can alter the protein alignment, however, its efficient usage towards fibrous structure formation in all the plant proteins needs further research. Further studies could focus on optimizing the concentration of L-cysteine for various plant proteins and exploring its effect at the molecular level to fully understand its potential usage in meat analog application.

Drainage and global warming increase the threat of carbon-rich northern peatlands drying up, which may cause a positive feedback loop, where the global warming is further accelerated. To better predict the feedback effects, the diversity and functions of soil microbial communities should be investigated. In particular, the role of intracellular parasites of soil is only little studied despite their high abundance. Bdellovibrio and like organisms (BALOs) is a phylogenetically heterogeneous group of obligate bacterial predators of Gram-negative bacteria. Due to their wide distribution and host range, BALOs may play an important role in regulating the structure and dynamics of microbial communities in soil and affect cycling processes. The ability to attack biofilms and prevent biofilm formation makes BALOs also potential candidates for various industrial, medical, agricultural, and biotechnological applications. The aim of the thesis was to characterize two BALOs previously isolated from the subarctic peat soil, Pallas, Finland: 2/ANJLi2 infecting Mucilaginibacter lappiensis and 2/K2C7 infecting Janthinobacterium sp., by using both culture-dependent and bioinformatics-based methods. Transmission electron microscopy (TEM) showed that the isolates display rod-shaped free-swimming cells with a single polar flagellum, morphology typical for BALOs. From a set of 40 strains representing 10 genera, two additional hosts were confirmed for 2/ANJLi2 and four additional hosts for 2/K2C7. In both cases, additional host strains belonged to the same genus, as the respective original isolation host, suggesting that the host range of the isolates is narrow. No host-independence growth was observed. Under TEM, different phases of the isolates’ life cycles could be observed, including free swimming BALO cells and the ones developing inside their host cells, which indicates a periplasmic life cycle. When 2/ANJLi2 and 2/K2C7 were incubated in liquid cultures with their original hosts, both BALOs obtained high titers of 108—109 plaque forming units per ml by 72 and 48 h post-infection, respectively, suggesting that the two isolates have effective but relatively slow life cycles. 2/K2C7 infection resulted in a clear drop of viable host cells, but 2/ANJLi2 infection seems to be less deleterious to its host cells. Genome analyses showed that the isolates are distantly related to each other and are new species of BALOs: 2/ANJLi2 is suggested to belong to the Bacteriovoracaceae family in the class Bacteriovoracia, while 2/K2C7 belongs to the Bdellovibrio genus in the class Bdellovibrionia. Identified gene functions were mostly related to protein synthesis, energy metabolism, and cell cycle. According to metabolic profiling, BALOs had fewer metabolic functions compared to their hosts. Many gene functions remained unknown, highlighting undersampling of soil BALOs and a need for more detailed future studies.

In Finland, peatland forests have been drained by ditching in order to increase stand growth. Due to e.g., ditch deterioration, ditch network maintenance (DNM) is required to lower the water table (WT) for better stand growth. Currently, DNM is timely for approximately 1.1 Mha of drained peatland forests in Finland. However, the implemented DNM operations are far from the target, resulting in shallower ditches. While DNM can increase stand growth, it also has some trade-offs. For example, DNM increases soil C emissions due to peat decomposition. Additionally, DNM can be irrelevant for mature sites. Therefore, careful analysis on the need of DNM is recommended to avoid unnecessary C emissions. The aim of this study was to analyse the effects of different ditch depths and shallowing on the stand C balances of drained peatland forests throughout Finland. The studied forest types included sites from nutrient rich to nutrient poor, representing a wide range of typical forestry sites, whereas the main tree species for each site was defined either as Scots pine or Norway Spruce, based on the characteristics of the forest type in question. Regional differences in climate and weather were taken into account by dividing Finland into four different regions. The research was implemented as a quantitative simulation study utilising SUSI peatland simulator. The simulator was used to calculate 10-year average stand C balances and late summer WTs for each site with three different ditch depths of 0.3 m, 0.6 m and 0.9 m. When considering shallowing, the ditch depths changed from 0.3 m to 0.2 m, from 0.6 m to 0.4 m and from 0.9 m to 0.6 m in a 20-years' time. The results indicated that a ditch depth between 0.3 m and 0.6 m was deep enough for most sites to reach a sufficient late summer WT. The only exception was the nutrient poor Vatkg, which required a deeper ditch of 0.9 m in most regions. Additionally, the effects of shallowing were clear, as all sites in all ditch depths saw increases in their stand C balances.