Growth Optimization and Time-Dependent Population Dynamics of Paramecium caudatum Using Locally Available Organic Substrates in Lake-Water Microcosms
Sabr Saad*
| Ibrahim M. Al-Salman | Abdulkhaleq S. Mahdy
© 2026 The authors. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).
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This research investigated the growth and population dynamics of Paramecium caudatum in lake-water microcosms using seven locally available organic substrates: poultry manure, sheep manure, cow dung, corn leaf powder, barley straw, palm fibre powder, and yeast solution, compared to natural lake water as a control. Water samples were collected from Hajra Lake. Treatments were made by the addition of nutrients to 1 L of lake water and supplemented with Chlorella sp. The samples were distributed into five replicates in sterile 200 mL glass containers, and 2 mL of pure P. caudatum culture (initial density 180 × 10³ cells/L per replicate) was added. Population counts were recorded over 44 days at 11 time points. The growth patterns varied significantly across treatments, with poultry manure proving to be the most effective, showing a peak population density of 1.4 × 10⁷ cells/L at day 40. Other substrates exhibited varying growth trends, with specific peak populations observed on different days. Statistical analysis revealed significant differences among treatments (p < 0.01). The findings highlight the importance of substrate composition and nutrient quality in optimizing the culture of P. caudatum, emphasizing poultry manure as the most suitable nutrient source for promoting ciliate growth, with potential applications in aquaculture and water quality management.
poultry manure, sheep manure, corn leaf powder, barley straw, palm fibre powder, yeast solution, Paramecium caudatum, water purification
Aquatic ecosystems are not only becoming more known to be important components of global sustainability due to their extensive geographic coverage, but also due to their role in providing a great percentage of global biodiversity, particularly aquatic invertebrates. The rise in the development of aquaculture as one of the most rapidly developing food production sectors is evidence of the increasing global demand for aquatic protein. However, the sustainability can be attributed to the equilibrium among environmental, economic, and social aspects [1]. Fish, oysters, shrimp, and other aquatic life have caused more stress to natural food webs and trophic relationships that, in most instances, have led to an ecological imbalance [2, 3]. The intensive systems can reduce the resilience of the ecosystem and affect productivity in the long term because of nutrient enrichment, chemical pollution, and habitat degradation [4]. This highlights the need to adopt sustainable solutions, such as recirculating aquaculture and ecosystem-based management techniques, to enhance productivity and reduce environmental impacts [5]. In this respect, the microbial ecology of water systems has been of great interest. Aquatic food webs are built on the basis of microorganisms, including bacteria, unicellular algae, and protozoa, which play an indispensable role in the ecosystem [6, 7]. They form the core of nutrient cycling, the decomposition of organic matter, and natural water purification, thereby maintaining water quality and ecosystem balance [8]. For example, bacteria stimulate the mineralization of organic compounds, whereas protozoa can control bacterial communities and facilitate energy transfer to higher trophic levels.
A study has found that microbial loop interactions contribute significantly to the productivity and nutrient supply of water bodies [9]. Similarly, Sherr and Sherr [10] reported the importance of protozoan grazing in controlling bacterial populations and increasing nutrient recycling. Protozoa, and ciliated protozoa in particular, are considered to occupy a strategic ecological position between microbial producers and higher consumers. The most widespread of them is Paramecium caudatum, a model organism due to its adaptability and ecological versatility. This ciliate can grow in various water bodies, including freshwater, seawater, and slightly salty water, and it is highly tolerant of the environment [11, 12]. Bacterial grazing is one of the major ecological roles that involves it taking huge amounts of bacteria, which in effect controls the growth of the bacteria, hence averting excessive growth of bacteria [10]. This grazing activity not only stabilizes the microbial communities but also increases the effectiveness of the microbial food web. Paramecium caudatum is also essential in nutrient cycling besides bacterial control. It aids in recycling inorganic nutrients, such as nitrogen and phosphorus, into the environment by consuming and digesting microbial biomass, which becomes accessible to primary producers [13]. This process supports continuous nutrient recycling and enhances primary productivity in aquatic environments [7]. In addition, P. caudatum participates in the decomposition of organic matter, including detritus and organic debris. Through its interactions with bacterial communities, it increases the rate at which complex organic substances are broken down into simpler substances, thereby enhancing nutrient fluxes at the ecosystem level [14, 15].
The present research aimed to determine how locally available substrates affect growth rate, maximum population density, and temporal dynamics of P. caudatum in lake water microcosms. Specifically, the study focused on identifying the suitability of different organic materials in the promotion of microorganism growth, to investigate the growth and population change dynamics of P. caudatum over a certain duration of time, and to identify possible cost-effective, sustainable sources of nutrients that will trigger the growth and maintenance of protozoans in water bodies. This study hypothesized that organic substrates promote the growth of bacteria and algae, thereby increasing P. caudatum populations and improving water quality through microbially mediated processes.
2.1 Water sample collection
Water samples were collected from the stagnant waters of Hajra Lake near the city of Sabha. The lake is used as a place to oxidize and filter the treated municipal wastewater. The sampling was done by means of a 1 L bottle fixed to a scrubber, with five replicates obtained from each point. The samples were immediately transported to the laboratory and transferred to a permanent culture system consisting of a 30 × 30 × 60 cm³ glass tank. Then, the samples were allowed to acclimate under laboratory conditions for one week. After acclimation, the initial abundance of Paramecium caudatum in the field samples was recorded, and a control sample was maintained for comparison.
2.2 Evaluation of substrate effects on the growth of microbes and protozoa
To evaluate the effect of different substrates on microbial and protozoan growth, seven environmentally available materials: poultry manure, sheep manure, cow manure, corn leaf powder, barley straw, palm fibre, and yeast solution were tested as treatments. The concentrations of substrates were as follows: poultry manure, sheep manure, and cow manure at 5 g dry weight/L; corn leaf powder, barley straw, and palm fibre at 3 g dry weight/L; and yeast solution at 1 mL/L. Each treatment was applied in five replicates using sterile 200 mL glass containers. After recording the initial P. caudatum count, 2 mL of a pure laboratory-prepared inoculum (1.8 × 103 cells/mL) was added to the substrate. The cultures were then monitored over time to assess growth, adaptation, and suitability of each substrate.
2.3 Preparation of cultures and nutrient treatment setup
To isolate pure Paramecium caudatum cultures, 1 L of lake water was used as the original sample. The sample was filtered using sterile filter paper. Sterile droppers were used to transfer a 1 mL aliquot to the filtered medium until the cell density matched that of the original sample. This standardized culture was used as the source of stock in subsequent experiments. The rest of the original sample was also filtered to obtain a growth medium whose physicochemical properties and nutrient composition were of a uniform nature. Five replicates of each treatment were prepared in 1 L glass beakers that were sterilized. The predetermined concentrations of the following substrates were then added: poultry manure, sheep manure, cow manure, yeast solution, corn leaf powder, barley straw, palm fibre, and the control, where no nutrient was added. Growth rates were determined with the help of these treatments, as well as the comparison of P. caudatum performance upon various nutrient regimes, following the standard protocols of media preparation and inoculation [8]. In addition, cultures were supplemented with Chlorella sp. as a primary food source to support bacterial and protozoan growth, ensuring a stable nutrient base for Paramecium caudatum.
2.4 Enumeration of physicochemical and biological parameters
The temperature of the water was measured after three days of employing a mercury thermometer, and the laboratory temperature was kept at 24-25 ℃. A Piccolo Plus pH meter (Hanna Instruments, Romania) was used to measure the pH of the control and all seven treatments, and was constant at 7.18 over the course of the experiment. Water was daily replaced through evaporation, with the amount of water lost in each treatment replenished by replenishing the remaining filtered medium. The results were measured after every four days during the experiment. The experiments were conducted in a constant laboratory environment in terms of lighting and temperature. Appropriate labelling was followed by the random mixing of samples. The number of Paramecium caudatum was counted with a hemocytometer under an Olympus CH20 compound microscope (Olympus Corporation, Japan; 10× magnification). The remaining slide was subdivided into longitudinal and transverse directions, and the number of protozoa was counted following the fixation of 10% formalin. Following the addition of water, slides were allowed to sit for 30 minutes to immobilize the organisms. Counts were recorded a total of eleven times over 44 days.
2.5 Statistical analysis
Differences among treatments were analyzed using one-way analysis of variance (ANOVA), followed by Tukey’s Honestly Significant Difference (HSD) test at a significance level of α = 0.01. Additionally, simple correlation coefficients were calculated to assess relationships among variables. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) software, and results were presented as mean ± standard error (SE) [16].
The growth rates of P. caudatum under different nutritional regimes are presented in Tables 1 and 2 and Figures 1-8. Growth responses varied across treatments, ranging from moderate to very high. All treatments containing organic substrates, including animal manures and plant fibres, supported significantly higher growth rates of Paramecium caudatum compared to the control (p < 0.001).
A comparison of Paramecium caudatum growth and reproduction among the different treatments showed a highly significant effect of medium composition on population dynamics (p = 4.26 × 10⁻³⁹), as shown in Table 2. The results showed that optimal growth conditions varied among substrates.
Table 1. Population density of Paramecium caudatum under different nutritional treatments (× 103 cells/L)
|
Treatment |
Initial Count |
Days of Incubation |
||||||||||
|
4 |
8 |
12 |
16 |
20 |
24 |
28 |
32 |
36 |
40 |
44 |
||
|
Control |
180 |
195 |
266 |
378 |
410 |
50 |
45 |
20 |
35 |
50 |
55 |
55 |
|
PM |
180 |
288 |
680 |
875 |
3970 |
4350 |
6100 |
7156 |
9932 |
12910 |
14000 |
8030 |
|
SM |
180 |
228 |
320 |
500 |
826 |
4100 |
2100 |
1044 |
800 |
460 |
470 |
490 |
|
CM |
180 |
350 |
428 |
810 |
944 |
1400 |
804 |
592 |
390 |
192 |
154 |
100 |
|
CLP |
180 |
560 |
810 |
910 |
1068 |
2450 |
2324 |
3170 |
1540 |
2110 |
2140 |
1120 |
|
BS |
180 |
281 |
406 |
436 |
562 |
1237 |
1157 |
1625 |
764 |
1054 |
1089 |
2230 |
|
PF |
180 |
250 |
300 |
430 |
650 |
820 |
1340 |
1150 |
354 |
330 |
2520 |
1498 |
|
YS |
180 |
700 |
876 |
2128 |
2174 |
2880 |
3500 |
3034 |
4900 |
5770 |
9000 |
4000 |
Table 2. Analysis of variance (ANOVA) with degrees of freedom (df)
|
Source |
Degree of Freedom |
Sum of Squares (SS) |
Mean Squares (MS) |
F-Value |
p-Value |
|
Treatment |
7 |
140170700 |
20024385.71 |
1657.32 |
4.26 × 10⁻³⁹** |
|
Error |
32 |
386636.6 |
12082.39 |
- |
- |
|
Total |
39 |
140557336.6 |
- |
- |
- |
Figure 1. Growth of Paramecium caudatum as the control experiment after 44 days of incubation
3.1 Growth of Paramecium caudatum as a control
In the control treatment, P. caudatum density increased from an initial count of 180 × 103 cells/L to 195 × 103 cells/L and 266 × 103 cells/L by days 4 and 8, respectively, reaching a peak on day 16 (410 × 103 cells/L). This was followed by a sharp decline to 50 × 103 cells/L by day 20 and a further decrease to 20 × 103 cells/L by day 28. A moderate recovery was observed, with counts rising to 55 × 103 cells/L on days 40 and 44 (Table 1 and Figure 1). Low dissolved oxygen (hypoxia), exhaustion of food sources that could have been available, possible contamination, or uneven sampling may explain the significant reduction in P. caudatum abundance, which occurred in the control group, between 410 × 103 cells/L and 50 × 103 cells/L between days 16 and 20. These dynamics indicate that the highest growth performance in the control medium occurred between days 12 and 16, after which growth was constrained by the limited availability of algae and naturally occurring bacteria as food resources. As the food supply became insufficient to sustain high P. caudatum numbers, the population declined, consistent with patterns of nutrient‑limited growth observed in protistan cultures under similar conditions [17-19].
3.2 Effect of poultry manure treatment on the growth of Paramecium caudatum
Poultry manure treatment on P. caudatum had a highly significant difference (p < 0.01) in growth compared to the control (Table 1 and Figure 2). Growth was initially slow, reached its peak on day 40, and then declined on day 44. An increase in P. caudatum density of 288 × 103 cells/L on day 4 to 680 × 103 cells/L and 875 × 103 cells/L on days 8 and 12, respectively, showed a significant increase in population. Peak values were observed on days 36 and 40, with values of about 1.3 × 107 and 1.4 × 107 cells/L, respectively, then a further decline to 8 × 106 cells/L on day 44. Days 20–24 are the period of significant rapid growth, while days 36–40 are the optimal harvest period. The extended high densities suggest that this medium offered better nutrient conditions and environmental factors for growth and survival over other treatments and the control. Various factors, such as long-term growth periods in nutrient-saturated environments, are in agreement with other recent research that has highlighted how resource enrichment and substrate quality can significantly alter protozoan population dynamics, as well as the carrying capacity of aquatic microcosms [20, 21].
Figure 2. Growth of Paramecium caudatum treated with poultry manure after 44 days of incubation
3.3 Sheep manure treatment and its effect on the growth of Paramecium caudatum
As shown in Table 1 and Figure 3, the initial population of P. caudatum was 180 × 103 cells/L, and it grew to 228 × 103 cells/L on day 4. Table 1 shows that the sheep manure's day 8 concentration is 320 × 103 cells/L, and the day 12 concentration is 500 × 103 cells/L, with a peak of about 4100 × 103 cells/L on day 20. Following this maximum, the density dropped to 2100 × 103 cells/L on day 24 and then proceeded to decline until the end of the experimental time. According to these time dynamics, the best period for growing the culture and harvesting it was between days 16 and 24 under test conditions. The identified trend of increased growth and then decreasing is not the first in numerous studies that have shown that nutrient enrichment and quality of substrates make a significant impact on the population trend of protozoan and microzooplanktons by modulating the availability of resources and their carrying capacity in aquatic microcosms [22].
Figure 3. Paramecium caudatum growth in the presence of sheep manure after a 44-day incubation period
3.4 Effect of cow manure treatment on the growth of Paramecium caudatum
Paramecium caudatum density increased from an initial value of 1.8 × 10⁵ cells/L to a maximum of 1.4 × 10⁶ cells/L on day 20, followed by a steady decrease in density to about 1.0 × 105 cells/L on day 44, as highlighted in Table 1 and Figure 4. These interaction patterns indicate that the most suitable days in terms of population growth and harvesting with this kind of treatment were 16-24 days. These findings also show that the overall survival and productivity of the culture were relative, with the highest densities of up to 1.4 × 106 cells/L. A potential reason for this trend is that the introduction of cow manure increased ammonia and other nitrogenous materials in the water-based medium. This could affect microbial activities and organism functions because the availability and toxicity of nitrogen would be altered [23]. Moreover, the eating activity of ciliates on organic debris can decrease the amount of available food, which also adds to the fact that population density can decrease over time. These results are consistent with more recent studies that indicate that alterations in nitrogen inputs may cause substantial changes in microbial community structure and growth success in aquatic ecosystems [24].
Figure 4. The Paramecium caudatum was grown in the presence of cow manure after 44 days of incubation
3.5 Influence of corn leaf powder treatment on the growth of Paramecium caudatum
The growth of P. caudatum started slowly and then suddenly peaked at 3.17 × 10⁶ cells/L on day 28, then fluctuated with a high of 1.12 × 106 cells/L on day 44 (Table 1 and Figure 5). The prolonged high population of P. caudatum was probably because the nutrients in the corn leaf powder were not released instantaneously but gradually. Corn leaf powder, being a plant-based product, is made up of plant cellulose, which releases nutrients slowly with time to give a prolonged supply of nutrients. The slowness of this degradation enables P. caudatum to persist longer in feeding on the accessible nutrients and still sustain high population levels. Due to the continuous release of organic matter, the protozoa have a continuous supply of food, resulting in prolonged growth even after a peak, a typical feature of substrates that sustain long-term nutrient supply to microbial and protozoan cultures. These findings show that the growth under this treatment was intermittent; the best time for the first harvest was between days 20 and 28, and a second harvest between days 36 and 40. The treatment had a high level of difference (p < 0.01) compared to the control. The long-term sustainability of the system over a long period can probably be explained by the gradual breakdown of the substrate particles, e.g., plant cellulose, which gives a long-term source of nutrients and habitat to P. caudatum, as has been proposed earlier [25].
Figure 5. Growth of Paramecium caudatum treated with corn leaf powder after 44 days of incubation
3.6 Effect of barley straw treatment on the growth of Paramecium caudatum
The growth of P. caudatum slowly rose to its peak on day 28 (1.625 × 106 cells/L), as illustrated in Table 1 and Figure 6, and the harvesting period was found to be from day 20 to day 28. Growth in this treatment was very significant compared to the control (p < 0.01). The findings also indicate that the medium enhanced waving but steady growth, which kept the population at par with time. These results indicate that barley straw has an appropriate substrate that can be used to develop multiple ciliates and small crustaceans, which is probably attributed to slow decomposition and the release of nutrients. Statistical comparisons with the control consistently showed highly significant differences across all measurement points (p < 0.01) [26].
Figure 6. Growth of Paramecium caudatum treated with barley straw after 44 days of incubation
3.7 Effect of palm fibre treatment on the growth of Paramecium caudatum
The population of P. caudatum increased slowly to a maximum of 1.3 × 106 cells/L on day 24 and 1.15 × 106 cells/L on day 28, then sharply decreased to 3.5 × 105 cells/L and 3.3 × 105 cells/L on days 32 and 36, respectively (Figure 7). An increment was noted on day 40, which reached the highest level of 2.5 × 106 cells/L and then decreased to 1.5 × 106 cells/L on day 44. These differences were highly significant (p < 0.01) compared to the control. The palm fibre treatment of P. caudatum displayed the first peak of population at days 24-28 with a subsequent decrease, and the second peak at day 40. The first peak was attributed to the nutrient content in the palm fibre that facilitated quick growth. But, with the loss of nutrient levels and the decreasing algae growth due to light attenuation by the palm fibre pigments, the population decreased. The second peak was when the slow-release nutrient of the palm fibre and organic matter recycling supported a recovery phase, so that the renewed growth and population resurgence were made possible. These observations are in agreement with earlier reports that show that substrate composition and light attenuation by pigments may greatly contribute to ciliate growth dynamics [27].
Figure 7. Growth of Paramecium caudatum treated with palm fibre after 44 days of incubation
3.8 Effect of yeast-treated medium on the growth of Paramecium caudatum
The growth of P. caudatum gradually increased in the yeast-treated medium until it reached the peak on day 40, amounting to 9.0 × 106 cells/L, and then declined to 4.0 × 106 cells/L on day 44 (Figure 8). Compared to the control, the results show a highly significant difference (p < 0.01). Therefore, the best harvest period was on days 32 to 40. However, when compared to the poultry manure treatment, it was observed that the latter recorded 1.4 × 107 cells/L. The corn leaf powder medium produced values close to those of the yeast medium, reaching 3.17× 106 cells/L. These results demonstrate the ability of naturally available media to compete, and achieving favourable growth across all treatments was very highly significant (Table 3).
Table 3. Tukey’s Honestly Significant Difference (HSD) statistical analysis
|
Group 1 |
Group 2 |
||||||
|
BS |
Control |
CLP |
CM |
PF |
PM |
SM |
|
|
Control |
-1613.91** |
|
|
|
|
|
|
|
CLP |
943.45** |
2557.36** |
|
|
|
|
|
|
CM |
-1195.27** |
418.64** |
-2138.73** |
|
|
|
|
|
PF |
-879.09** |
734.82** |
-1822.35** |
316.18** |
|
|
|
|
PM |
4455.00** |
6068.91** |
3511.55** |
5650.27** |
5334** |
|
|
|
SM |
-594.00** |
1019.91** |
-1537.45** |
601.27** |
285.09** |
-5049.00** |
|
|
YS |
1786.36** |
3460.27** |
842.91** |
2981.64** |
2665.45** |
-2668.64** |
2380.36** |
Figure 8. Growth of Paramecium caudatum in yeast-treated medium after 44 days of incubation
The findings of the current study demonstrated that all treatments had a significant effect on the growth of Paramecium caudatum compared with the control (p < 0.01). Poultry manure was the optimal substrate, having the highest number of cells (1.3 × 107 cells/L - 1.4 × 107 cells/L) at optimal harvest times (days 36 - 40). The growth of the various substrates produced a specific growth pattern, with the best harvest time depending on the substrate. The additives had effects on the bacterial and microalgal populations, which form the major source of food to P. caudatum, and other additives, like palm fibre, discharged pigments that inhibited algal growth. The majority of treatments raised the media pH to slightly alkaline conditions, which adds to long-term ciliate viability. These results underline the importance of the substrate composition and nutrient quality in the maximization of protozoan culture productivity.
[1] Garlock, T.M., Asche, F., Anderson, J.L., Eggert, H., Anderson, T.M., Che, B., Tveteras, R. (2024). Environmental, economic, and social sustainability in aquaculture: The aquaculture performance indicators. Nature Communications, 15(1): 5274. https://doi.org/10.1038/s41467-024-49556-8
[2] Mizuta, D.D. (2024). Dietary shifts and the need for increased sustainability approaches in the global aquaculture seafood system. Frontiers in Sustainable Food Systems, 8: 1356492. https://doi.org/10.3389/fsufs.2024.1356492
[3] Ahmed, N., Thompson, S., Turchini, G.M. (2020). Organic aquaculture productivity, environmental sustainability, and food security: Insights from organic agriculture. Food Security, 12(6): 1253-1267. https://doi.org/10.1007/s12571-020-01090-3
[4] Boesch, D.F. (2002). Challenges and opportunities for science in reducing nutrient over-enrichment of coastal ecosystems. Estuaries, 25(4): 886-900. https://doi.org/10.1007/BF02804914
[5] Naylor, R.L., Hardy, R.W., Buschmann, A.H., Bush, S.R., Cao, L., Klinger, D.H., Troell, M. (2021). A 20-year retrospective review of global aquaculture. Nature, 591(7851): 551-563. https://doi.org/10.1038/s41586-021-03308-6
[6] Hou, Y., Jia, R., Ji, P., Li, B., Zhu, J. (2022). Organic matter degradation and bacterial communities in surface sediment influenced by Procambarus clarkia. Frontiers in Microbiology, 13: 985555. https://doi.org/10.3389/fmicb.2022.985555
[7] Azam, F., Fenchel, T., Field, J.G., Gray, J.S., Meyer-Reil, L.A., Thingstad, F. (1983). The ecological role of water-column microbes in the sea. Marine Ecology Progress Series, 10(3): 257-263. https://doi.org/10.7208/chicago/9780226125534-024
[8] Gupta, P.K., Gandhi, M. (2023). Bioremediation of organic pollutants in soil–water system: A review. BioTech, 12(2): 36. https://doi.org/10.3390/biotech12020036
[9] Fenchel, T. (2008). The microbial loop–25 years later. Journal of Experimental Marine Biology and Ecology, 366(1-2): 99-103. https://doi.org/10.1016/j.jembe.2008.07.013
[10] Sherr, E.B., Sherr, B.F. (2002). Significance of predation by protists in aquatic microbial food webs. Antonie Van Leeuwenhoek, 81(1): 293-308. https://doi.org/10.1023/A:1020591307260
[11] Li, F., Yang, J., Li, J., Lin, X. (2024). Adaptive strategies and underlying response mechanisms of ciliates to salinity change with note on fluctuation properties. Microorganisms, 12(10): 1957. https://doi.org/10.3390/microorganisms12101957
[12] Madoni, P. (2011). Protozoa in wastewater treatment processes: A minireview. Italian Journal of Zoology, 78(1): 3-11. https://doi.org/10.1080/11250000903373797
[13] Ren, Y., Shi, W., Chen, J., Li, J. (2024). Water quality drives the reconfiguration of riverine planktonic microbial food webs. Environmental Research, 249: 118379. https://doi.org/10.1016/j.envres.2024.118379
[14] Wang, X., Liu, J., Chai, B., Wu, T. (2025). Protozoa-driven micro-food webs shaping carbon and nitrogen cycling in reservoir ecosystems. Environmental Microbiome, 20(1): 109. https://doi.org/10.1186/s40793-025-00772-9
[15] Mamun, M., Kim, J.Y., An, K.G. (2021). Multivariate statistical analysis of water quality and trophic state in an artificial dam reservoir. Water, 13(2): 186. https://doi.org/10.3390/w13020186
[16] Budziak, M., Fyda, J. (2024). Effect of microplastic particles on the population growth rate and clearance rate of selected ciliates (Protista, Ciliophora). Environmental Science and Pollution Research, 31(5): 6907-6921. https://doi.org/10.1007/s11356-023-31635-w
[17] Yang, J., Wei, H., Yalin, T., Alan, W., Xiaofeng, L., Jiqiu, L. (2019). Combined effects of food resources and exposure to ammonium nitrogen on population growth performance in the bacterivorous ciliate Paramecium caudatum. European Journal of Protistology, 71: 125631. https://doi.org/10.1016/j.ejop.2019.125631
[18] Gao, Y., Solberg, T., Wang, R., Yu, Y., Al-Rasheid, K.A., Gao, F. (2024). Application of RNA interference and protein localization to investigate housekeeping and developmentally regulated genes in the emerging model protozoan Paramecium caudatum. Communications Biology, 7(1): 204. https://doi.org/10.1038/s42003-024-05906-2
[19] Bulannga, R.B., Schmidt, S. (2024). Micro-and nanoplastics in freshwater ecosystems—Interaction with and impact upon bacterivorous ciliates. Frontiers in Earth Science, 12: 1349865. https://doi.org/10.3389/feart.2024.1349865
[20] DeWitt, K., Carrell, A.A., Rocca, J.D., Votzke, S., Yammine, A., Peralta, A.L., Gibert, J.P. (2025). Predation by a ciliate community mediates temperature and nutrient effects on a peatland prey prokaryotic community. Msphere, 10(7): e00309-25. https://doi.org/10.1128/msphere.00309-25
[21] Van Houten, J. (2023). A review for the special issue on Paramecium as a modern model organism. Microorganisms, 11(4): 937. https://doi.org/10.3390/microorganisms11040937
[22] Yun, S.C., Jeong, H., Lee, J.S., Kim, J.H., Kim, I.C., Maszczyk, P., Lee, J.S. (2025). A review of ammonia toxicity on aquatic organisms: Species-specific responses, microbial shifts, and environmental interactions. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 110388. https://doi.org/10.1016/j.cbpc.2025.110388
[23] Kitamura, R., Kozaki, T., Ishii, K., Iigo, M., Kurokura, T., Yamane, K., Saito, T. (2021). Utilizing cattle manure compost increases ammonia monooxygenase A gene expression and ammonia-oxidizing activity of both bacteria and archaea in biofiltration media for ammonia deodorization. Microbes and Environments, 36(2): ME20148. https://doi.org/10.1264/jsme2.ME20148
[24] Li, H., Xu, Y., Wang, Y., Cui, Y., Lin, J., Zhou, Y., Tang, R. (2023). Material-engineered bioartificial microorganisms enabling efficient scavenging of waterborne viruses. Nature Communications, 14(1): 4658. https://doi.org/10.1038/s41467-023-40397-5
[25] Giang, N.D.C., Dung, T.V., Dong, N.M., Phuong, N.M., Long, V.V. (2024). Effects of organic substrate amendments on selected organic fractions and biochemical parameters under different soils. Scientifica, 2024(1): 9997751. https://doi.org/10.1155/2024/9997751
[26] Schostag, M., Priemé, A., Jacquiod, S., Russel, J., Ekelund, F., Jacobsen, C.S. (2019). Bacterial and protozoan dynamics upon thawing and freezing of an active layer permafrost soil. The ISME Journal, 13(5): 1345-1359. https://doi.org/10.1038/s41396-019-0351-x
[27] Kosiba, J., Krztoń, W., Koreiviené, J., Tarcz, S., Wilk-Woźniak, E. (2022). Interactions between ciliate species and Aphanizomenon flos-aquae vary depending on the morphological form and biomass of the diazotrophic cyanobacterium. International Journal of Environmental Research and Public Health, 19(22): 15097. https://doi.org/10.3390/ijerph192215097