CAPITULO VI: PROPUESTA DE IMPLEMENTACIÓN DEL SGC
6.5 Resultados esperados
hansenii, Amphora coffeaeformis and Oscillatoria species.
Microbial biomass
Chlorophyll a concentrations in treatment N, O and NO (Figure 4.3 A) increased during the first week of the experiment and decreased rapidly afterwards. In all other treatments chlorophyll a concentrations continuously increased until the end of the experiment, except in treatment AO (Figure 4.3 B). At the end of the experiment AO was significantly lower in Chl a value than ANO and AN (MW test, U=2, p<0.05).
CHAPTER 4. Coexistence of organisms: EPS production
69
Figure 4.3:Mean values (n=5 per treatment ±SE) of measurements over the course of
the experiment. (A) The different treatments were single culture: ▲- Amphora; ◊ - Navicula;
●
- Oscillatoria and their mixture:□
- Amphora + Navicula + Oscillatoria. (B) Pairs of mixed cultures:∆ - Amphora + Navicula, ○
- Amphora+ Oscillatoria;♦
-Navicula + Oscillatoria and their mixture:
□
- Amphora + Navicula + Oscillatoria; ■- Control.CHAPTER 4. Coexistence of organisms: EPS production
70
The most pronounced increases were observed for treatments A, AN, AO, ANO (Figure 4.4 A, Table 4.1). The were significant differences in the medians of the chlorophyll a
concentrations (KW, χ2=34.7, df=6, p<0.001). For instance on day 12 (given as example) treatments ANO and AO were significantly higher than N, O and NO (MW test, U=0, p<0.01) and ANO was significantly higher than AN (MW test, U=2, p<0.05). The single culture A and AN were significantly higher than N, O and NO (MW test, U=0, p<0.01). The highest microbial biomasses were observed in mixed treatments AN, AO and ANO and the single culture A where chlorophyll a concentration was up to 9 times higher than the other treatments N, O and NO (Figure 4.4 B, Table 4.1).
Table 4.1.Quotient/ factors for Chlorophyll a, EPS carbohydrates, EPS proteins between the first day of sampling (day 1) and day 12 where most of the variables showed their maximum value as well as differences between mixed assemblages “ANO” and the given treatments (A, N, O, AN, AO, NO, ANO).
Factor Treatment Chlorophyll
a Carbohydrates Proteins Between minimum and maximum values reached A 9.8 1.8 2.5 N 0 1.1 1.7 O 1.7 1.3 2.8 AN 9.4 2.6 3.2 AO 6.2 2.2 3.7 NO 4.8 1.6 3.8 ANO 7.6 2.7 2.6 Between ANO and single and combined treatments A 1.1 1.2 1.3 N 34.8 2.6 1.7 O 5.8 2.1 1.0 AN 1.2 1 1.0 AO 1.3 1 0.7 NO 9.2 2.2 0.9
CHAPTER 4. Coexistence of organisms: EPS production
71
Figure 4.4: The differences in chlorophyll a concentrations: (A) between the first sampling day and day 12 where most of the variables showed their maximum value. (B) Cumulative chlorophyll a concentrations (n=25) during 2 weeks of experiment. The treatment name (Diatom species) was given according to the first letter of the corresponding culture (s) inoculated: A for Amphora, N for Navicula, O for Oscillatoria and their mixture AN for Amphora and Navicula, AO for Amphora and Oscillatoria, NO for Navicula and Oscillatoria and ANO for Amphora, Navicula and Oscillatoria.
CHAPTER 4. Coexistence of organisms: EPS production
72
Changes in EPS components
The colloidal carbohydrate concentrations increased in all treatments over time (except the control) and reached a maximum on day 15 (Figure 4.5 A and B). However this increase was more pronounced in treatments ANO, AO and AN rather with single treatment A (Figure 4.6 A and B Table 4.1). Statistical testing per day revealed that on day 12, treatments ANO, AN and AO were significantly higher than treatments N, O and NO (KW test, χ2=33.4, df=6, p<0.001, MW test, U=0, p<0.001). The carbohydrates
in the control were below detection limits.
Water–extractable (colloidal) protein concentrations increased in all treatments, (except in the control) up to day 4, followed by a rapid decrease to day 7 and then continuous increase until the end of experiment day 15 (Figure 4.7 A and B).
Protein concentration for all treatments reached a maximum on the last day of the experiment with a more pronounced increase (up to 3.8 times) for treatments AO and NO (Figure 4.8 A, Table 4.1), however cumulative protein concentration was higher in treatments O, AO, NO and ANO followed by AN, A and N (Figure 4.8 B). On the last day of the experiment treatment AO was significantly higher than all other treatments (KW test, χ2=32.2, df=7, p<0.001, MW test, U=0, p<0.001 for all treatments), treatment
NO was significantly higher than A and N (MW test, U=1, p<0.05), treatments AN and ANO was significant higher than A and N (MW test, U=1, p<0.05) and treatment O was significant higher than N (MW test, U=0, p<0.01).
CHAPTER 4. Coexistence of organisms: EPS production
73
Figure 4.5: Mean values (n=5 per treatment) with SE of colloidal carbohydrate measurements over the course of the experiment. (A) The different treatments were single culture: ▲- Amphora; ◊ -Navicula;
●
- Oscillatoria and their mixture:□
- Amphora + Navicula + Oscillatoria. (B) Pairs of mixed cultures: ∆ - Amphora + Navicula,○ - Amphora+ Oscillatoria; ♦
- Navicula + Oscillatoria and their mixture: □ - Amphora +CHAPTER 4. Coexistence of organisms: EPS production
74
Figure 4.6: The differences incolloidal carbohydrates concentrations: (A) between the first sampling day and day 12where most of the variables showed their maximum value. (B) Cumulative carbohydrates concentrations (n=25) during 2 weeks of experiment. The treatment name (Diatom species) was given according to the first letter of the corresponding culture (s) inoculated: A for Amphora, N for Navicula, O for Oscillatoria and their mixture AN for Amphora and Navicula, AO for Amphora and Oscillatoria, NO for Navicula and Oscillatoria and ANO for Amphora, Navicula and Oscillatoria.
CHAPTER 4. Coexistence of organisms: EPS production
75
Figure 4.7: Mean values (n=5 per treatment) with SE of colloidal protein measurements over the course of the experiment. (A) The different treatments were single culture: ▲-
Amphora; ◊ -Navicula;
●
- Oscillatoria and their mixture:□
- Amphora + Navicula + Oscillatoria. (B) Pairs of mixed cultures:∆ - Amphora + Navicula, ○
- Amphora+ Oscillatoria;♦
- Navicula + Oscillatoria and their mixture:□ - Amphora + Navicula +
Oscillatoria; ■-Control.CHAPTER 4. Coexistence of organisms: EPS production
76
Figure 4.8: The differences in colloidal protein concentrations: (A) between the first sampling day and day 12where most of the variables showed their maximum value. (B) Cumulative carbohydrates concentrations (n=25) during 2 weeks of experiment. The treatment name (Diatom species) was given according to the first letter of the corresponding culture (s) inoculated: A for Amphora, N for Navicula, O for Oscillatoria and their mixture AN for Amphora and Navicula, AO for Amphora and Oscillatoria, NO for Navicula and Oscillatoria and ANO for Amphora, Navicula and Oscillatoria.
CHAPTER 4. Coexistence of organisms: EPS production
77
Relationship between biological variables
A positive correlation was determined between colloidal carbohydrates and colloidal proteins (Pearson correlation coefficient, r=0.410, n=35, p<0.01). A positive linear relationship was determined between colloidal carbohydrates and microalgal biomass, as indicated by Chl a concentrations (Figure 4.9), however no significant relationship was found between colloidal proteins and chlorophyll a.
y = 0.19x - 3.93
R
2= 0.259
n=35
p<0.001
0
1
2
3
1
2
3
4
5
Carbohydrates (μg cm
-3)
C
h
lo
ro
p
h
y
ll
a
(
μ
g
c
m
-3)
Figure 4.9: Relationship between colloidal carbohydrates and chlorophyll a.
4.3.2. Experiment 2: Interaction of microorganisms (heterotrophic bacteria and