Dietary Supplementation with Rhodotorula mucilaginosa Enhances Resistance to Aeromonas veronii Infection in Red Claw Crayfish (Cherax quadricarinatus)

Abstract

The objective of this study was to evaluate the effects of dietary supplementation with different levels of Rhodotorula mucilaginosa (0.0 g/kg, 0.1 g/kg, 1.0 g/kg, and 10.0 g/kg) on resistance to Aeromonas veronii infection in red claw crayfish (Cherax quadricarinatus) (initial body weight of 0.13 ± 0.06 g). The investigation combined a 56-day feeding trial with a subsequent 7-day infection challenge to assess cumulative mortality, immune and antioxidant enzyme activities, and the relative expression of immune-related genes. During the A. veronii infection test, the cumulative mortalities for the 0.1 g/kg, 1.0 g/kg, and 10.0 g/kg groups were 44.44%, 38.89%, and 38.89%, respectively, all significantly lower (p < 0.05) than that of the control group (58.33%). Compared with the control group, after infection with A. veronii, the activities of acid phosphatase, alkaline phosphatase, catalase, and superoxide dismutase in the hepatopancreas and alkaline phosphatase, lysozyme in the hemolymph of red claw crayfish in the 1.0 g/kg group significantly increased (p < 0.05). The activities of aspartate aminotransferase and alanine aminotransferase in the hemolymph of red claw crayfish in the 1.0 g/kg group significantly decreased (p < 0.05). The relative expression levels of serine protease inhibitor, crustacean hyperglycemic hormone, anti-lipopolysaccharide factor, and superoxide dismutase genes in the hepatopancreas of red claw crayfish in the 1.0 g/kg group were significantly upregulated (p < 0.05). In conclusion, R. mucilaginosa could significantly improve the antibacterial ability of red claw crayfish against A. veronii. In this experimental context, the ideal addition level of R. mucilaginosa is determined to be 1.0 g/kg.

Keywords: Aeromonas veronii; Cherax quadricarinatus; Rhodotorula mucilaginosa; antioxidant; immune.

Figure 1

The effects of Rhodotorula mucilaginosa on the cumulative mortality of red claw crayfish infected with Aeromonas veronii. All the data are presented as the mean ± SD (n = 3).

Figure 2

The effects of Rhodotorula mucilaginosa on the activity of acid phosphatase (ACP) in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All the data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 3

The effects of Rhodotorula mucilaginosa on the activity of alkaline phosphatase (AKP) in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All the data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 4

The effects of Rhodotorula mucilaginosa on the activity of catalase (CAT) in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 5

The effects of Rhodotorula mucilaginosa on the activity of superoxide dismutase (SOD) in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 6

The effects of Rhodotorula mucilaginosa on the content of total protein (TP) in the hemolymph of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 7

The effects of Rhodotorula mucilaginosa on the activity of alkaline phosphatase (AKP) in the hemolymph of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 8

The effects of Rhodotorula mucilaginosa on the activity of lysozyme (LZM) in the hemolymph of red claw crayfish infected with Aeromonas veronii. All the data are presented as mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 9

The effects of Rhodotorula mucilaginosa on the activity of aspartate aminotransferase (AST) in the hemolymph of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 10

The effects of Rhodotorula mucilaginosa on the activity of alanine aminotransferase (ALT) in the hemolymph of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 11

The effects of Rhodotorula mucilaginosa on the relative expression levels of the serine protease inhibitor (spi) gene in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All the data are presented as mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 12

The effects of Rhodotorula mucilaginosa on the relative expression levels of the superoxide dismutase (sod) gene in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 13

The effects of Rhodotorula mucilaginosa on the relative expression levels of the crustacean hyperglycemic hormone (chh) gene in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.

Figure 14

The effects of Rhodotorula mucilaginosa on the relative expression levels of the anti-lipopolysaccharide factor (alf) gene in the hepatopancreas of red claw crayfish infected with Aeromonas veronii. All data are presented as the mean ± SD (n = 3). In the graph, different superscript lowercase letters indicate statistically significant differences (p < 0.05) among the values across the different groups at the same time. Different superscript capital letters indicate statistically significant differences (p < 0.05) among the values across different times within the same group.