博士 / 國立屏東科技大學 / 水產養殖系所 / 106 / The aims of this study were to (1) develop a relevant synbiotic to promote growth perfomance of the white shrimp, Litopenaeus vannamei; (2) discover some new insights into the mechanisms of action how synbiotic can exert growth of L. vannamei by using next generation sequencing (NGS) technology and metabolomic approaches; and (3) confirm whether identifed metabolites assuredly exert the growth of L. vanamei. Firstly, three common prebiotics, including fructooligosaccharide (FOS), galactooligosaccharide (GOS) and mannan oligosaccharide (MOS), were screened for supporting the growth of Lacto. plantarum 7-40, prebiotic score, and abilities to induce bacterial enzyme activities of protease, leu-aminopeptidase, and β-galactosidase. Results showed that growth of Lacto. plantarum 7-40 significantly increased after adding GOS as the sole carbon source. GOS induced the highest activities of protease and β-galactosidase by Lacto. plantarum 7-40. These results indicated that GOS was more suitable for combining with Lacto. plantarum 7-40 as a synbiotic for shrimp than FOS and MOS. For growth performance trial, four experimental diets, including a basal diet with no GOS or Lacto. plantarum 7-40 (control), 0.4% GOS (PRE), 108 CFU Lacto. plantarum 7-40 kg 1 (PRO), and 0.4% GOS in combination with 108 CFU Lacto. plantarum 7-40 kg 1 (SYN), were given to shrimp. At the end of a 60-day feeding trial, shrimp fed the SYN diet had significantly higher weight gain (WG), specific growth rate (SGR), lactic acid bacteria (LAB) and intestinal enzyme activities, including protease, leu-aminopeptidase, and β-galactosidase, compared to the control. We firstly concluded that dietary Lacto. plantarum 7-40 and GOS had a synergistic effect on improving the growth performance, intestinal microbiota, and digestive enzyme activities of L. vannamei.
Secondly, to discover new insights into the mechanisms of action, shrimp from the synbiotic and control treatments were sampled for the elucidation of intestinal microbial communities by using the next generation DNA sequencing analyses and the detection of the changes in metabolic profiles in hepatopancreas of shrimp were examined by using 1H nuclear magnetic resonance (NMR)-based metabolomic analyses, then reverse-phase high-performance liquid chromatography (RP-HPLC) and spectrophotometric analyses were used to confirm significantly altered metabolites in the hepatopancreas and plasma of shrimp in all groups. Results showed that 6 phyla, 11 classes, 19 orders, 30 families, 58 genera and 73 species with taxonomical names were assigned. The majority of OTUs were shared between synbiotic and control shrimps composed of 37 OTUs. However, intestinal biodiversity analyses revealed that SYN-fed shrimp had higher species richness, eveness, and Shannon-Weaver index than those of the control shrimp, but no statistical significance. Interestingly, shrimp that were fed SYN diet improved colonization of Lacto. plantarum and reduced prevalences of V. harveryi and Photobacterium damselae in the intestines. In addition, results from the 1H NMR analyses unraveled that 22 hepatopancreas metabolites were matched and identified between the SYN- and control- fed shrimp. Among hepatopancreatic metabolites, inosine monophosphate (IMP), valine, and betaine, significantly increased in the SYN group. Confirmation using RP-HPLC and spectrophotometric methods showed that IMP presented high amounts in the hepatopancreas, but not in the plasma of shrimp; in contrast, valine and betaine were in high concentrations in both the hepatopancreas and plasma.
Finally, to confirm whether identifed metabolites assuredly exert the growth of L. vanamei, a confimatory study on the effects of metabolite-supplemented diets on growth of L. vannamei was carried out. Six experimental diets, including 0.1% inosine monophosphate (IMP); 0.5% valine (VAL); 0.5% betaine (BET); 0.1% IMP + 0.5% valine + 0.5% betaine (META); synbiotic (SYN); and the control diet (added nothing) were given to shrimp. After the 60-day feeding regimen, results showed that shrimp fed either IMP- or META-supplemented diets significantly increased WG and SGR than that of shrimp in the BET and control groups. In conclusion, results suggested that GOS and the Lacto. plantarum 7-40 had a synergistic effects on growth performance of L. vannamei. Feeding a synbiotic comprised of 0.4% GOS and Lacto. plantarum 7-40 at 108 CFU kg-1 of feed can alter intestinal microbial communities of shrimp by inducing colonization of Lacto. plantarum in the intestine of shrimp and reducing the prevalence of Vibriosis in the intestine of shrimp. In presence of GOS, Lacto. plantarum 7-40 exhibited higher production levels of intestinal protease, leu-aminopeptidase, β-galactosidase enzymes that play important roles in protein digestibility and sugar digestion. Combination of GOS and Lacto. plantarum 7-40 siginificantly increased crucial metabolites, including IMP, valine, and betaine in the hepatopanreas and plasma of shrimp, that would be the important components in protein and energy metabolism in shrimp, of which IMP, a nucleotide, could be a main factor to improve growth performance of L. vannamei.
| Identifer | oai:union.ndltd.org:TW/106NPUS5086001 |
| Date | January 2018 |
| Creators | Huynh, Truong-Giang, 黃長江 |
| Contributors | Liu, Chun-Hung, 劉俊宏 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 150 |
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