Whole-Genome Sequence of Pseudoalteromonas sp. NC201, a Probiotic Strain for Litopenaeus stylirostris Hatcheries in New Caledonia

Sorieul L, Rückert C, Al-Dilaimi A, et al. Whole-Genome Sequence of Pseudoalteromonas sp. NC201, a Probiotic Strain for Litopenaeus stylirostris Hatcheries in New Caledonia. Microbiology resource announcements. 2019;8(34): e00477-19.The marine bacterium Pseudoalteromonas sp. strain NC201 has shown probiotic potential in Litopenaeus stylirostris rearing. In this study, the complete genome of NC201 was sequenced. This genome consists of a chromosome (4.13Mb) and a chromid (1.24Mb). The genome contains gene clusters coding for antibacterial peptides and secondary metabolites. Copyright © 2019 Sorieul et al

Pseudoalteromonas sp. NC201, isolated in New Caledonia, a probiotic strain for Litopenaeus stylirostris shrimp farming : characterization and impact on the shrimp’s physiology

La souche Pseudoalteromonas sp. NC201, isolée en Nouvelle-Calédonie, possède des propriétés antibactériennes et probiotiques dans le cadre d’élevages larvaires de crevettes. Ainsi, cette souche bactérienne constitue une alternative à l’utilisation des antibiotiques. Ce travail de thèse a été focalisé sur la caractérisation de NC201 et de son potentiel antimicrobien ainsi que sur l’étude de son effet sur la crevette, Litopenaeus stylirostris lors de challenges expérimentaux. L’analyse du génome de NC201 a révélé la présence de clusters de gènes codants des composés antimicrobiens ainsi que deux amino acides oxydases. Une de ces oxydases a été identifiée comme capable d’inhiber des Vibrio pathogènes de L. stylirostris. Les essais in vivo ont permis de confirmer le rôle probiotique de NC201. En effet NC201 a été responsable d’une amélioration de la survie des animaux lors de stress hypo et hypersalins mais aussi lors de challenge biotique par infection avec V. nigripulchritudo. Le suivi dans l’hémolymphe de NC201 et V. nigripulchritudo a mis en évidence que ces deux bactéries étaient capables individuellement de coloniser l’hémolymphe des animaux, cependant, une exclusion mutuelle des deux bactéries a été observée dans ce compartiment. L’expression de gènes liés à la réponse immunitaire ainsi qu’à la réponse au stress oxydant a été quantifiée suite au traitement probiotique et au challenge avec V. nigripulchritudo. La quantification et l’activité enzymatique de biomarqueurs du stress oxydant ont été mesurées. Les modulations de ces biomarqueurs ont révélé que la souche NC201 conférait aux crevettes un état de santé général plus performant pour répondre à des stress.The Pseudoalteromonas sp. NC201 strain, isolated in New Caledonia, displayed antibacterial and probiotic properties in shrimp hatcheries. This strain is an alternative to antibiotics use. This thesis focused on the characterization of NC201, its antimicrobial potential as well as on the study on its effect on Litopenaeus stylirostris during experimental challenges. The analysis of the complete genome sequence of NC201 revealed multiple clusters coding for potential antimicrobial compounds as well as two amino acid oxidases. One of these oxidases was identified as capable of inhibiting Vibrio pathogenic to L. stylirostris such as V. penaeicida and V. nigripulchritudo. In vivo trials confirmed the probiotic role of NC201 towards L. stylirostris. Indeed NC201 was responsible for higher survival rates in animals confronted to hypo and hypersaline stress as well as to bacterial challenge through infection with V. nigripulchritudo. During experimental infections the presence of NC201 and V. nigripulchritudo was monitored in the shrimp hemolymph. Both bacteria are capable of invading the shrimp’s hemolymph but seemed mutually exclusive in this compartment during the 24 hours following the infection. The expression profile of genes involved in the immune response and the response to oxidative stress were quantified in the hemolymph and hepatopancreas, respectively. Enzymatic activities and quantification of bioindicators of oxydative stress were measured in the hepatopancreas. These modulations highlighted that NC201 induced an increase in the shrimp overall health status leading to enhanced responses to stresses

Pseudoalteromonas sp. NC201, un probiotique isolé en Nouvelle-Calédonie pour l'élevage de la crevette Litopenaeus stylirostris : Caractérisation et impact sur l’état physiologique de la crevette

La souche Pseudoalteromonas sp. NC201, isolée en Nouvelle-Calédonie, possède des propriétés antibactériennes et probiotiques dans le cadre d’élevages larvaires de crevettes. Ainsi, cette souche bactérienne constitue une alternative à l’utilisation des antibiotiques. Ce travail de thèse a été focalisé sur la caractérisation de NC201 et de son potentiel antimicrobien ainsi que sur l’étude de son effet sur la crevette, Litopenaeus stylirostris lors de challenges expérimentaux. L’analyse du génome de NC201 a révélé la présence de clusters de gènes codants des composés antimicrobiens ainsi que deux amino acides oxydases. Une de ces oxydases a été identifiée comme capable d’inhiber des Vibrio pathogènes de L. stylirostris. Les essais in vivo ont permis de confirmer le rôle probiotique de NC201. En effet NC201 a été responsable d’une amélioration de la survie des animaux lors de stress hypo et hypersalins mais aussi lors de challenge biotique par infection avec V. nigripulchritudo. Le suivi dans l’hémolymphe de NC201 et V. nigripulchritudo a mis en évidence que ces deux bactéries étaient capables individuellement de coloniser l’hémolymphe des animaux, cependant, une exclusion mutuelle des deux bactéries a été observée dans ce compartiment. L’expression de gènes liés à la réponse immunitaire ainsi qu’à la réponse au stress oxydant a été quantifiée suite au traitement probiotique et au challenge avec V. nigripulchritudo. La quantification et l’activité enzymatique de biomarqueurs du stress oxydant ont été mesurées. Les modulations de ces biomarqueurs ont révélé que la souche NC201 conférait aux crevettes un état de santé général plus performant pour répondre à des stress.The Pseudoalteromonas sp. NC201 strain, isolated in New Caledonia, displayed antibacterial and probiotic properties in shrimp hatcheries. This strain is an alternative to antibiotics use. This thesis focused on the characterization of NC201, its antimicrobial potential as well as on the study on its effect on Litopenaeus stylirostris during experimental challenges. The analysis of the complete genome sequence of NC201 revealed multiple clusters coding for potential antimicrobial compounds as well as two amino acid oxidases. One of these oxidases was identified as capable of inhibiting Vibrio pathogenic to L. stylirostris such as V. penaeicida and V. nigripulchritudo. In vivo trials confirmed the probiotic role of NC201 towards L. stylirostris. Indeed NC201 was responsible for higher survival rates in animals confronted to hypo and hypersaline stress as well as to bacterial challenge through infection with V. nigripulchritudo. During experimental infections the presence of NC201 and V. nigripulchritudo was monitored in the shrimp hemolymph. Both bacteria are capable of invading the shrimp’s hemolymph but seemed mutually exclusive in this compartment during the 24 hours following the infection. The expression profile of genes involved in the immune response and the response to oxidative stress were quantified in the hemolymph and hepatopancreas, respectively. Enzymatic activities and quantification of bioindicators of oxydative stress were measured in the hepatopancreas. These modulations highlighted that NC201 induced an increase in the shrimp overall health status leading to enhanced responses to stresses

β-1,4-Xylan backbone synthesis in higher plants: How complex can it be?

Xylan is a hemicellulose present in the cell walls of all land plants. Glycosyltransferases of the GT43 (IRX9/IRX9L and IRX14/IRX14L) and GT47 (IRX10/IRX10L) families are involved in the biosynthesis of its β-1,4-linked xylose backbone, which can be further modified by acetylation and sugar side chains. However, it remains unclear how the different enzymes work together to synthesize the xylan backbone. A xylan synthesis complex (XSC) has been described in the monocots wheat and asparagus, and co-expression of asparagus AoIRX9, AoIRX10 and AoIRX14A is required to form a catalytically active complex for secondary cell wall xylan biosynthesis. Here, we argue that an equivalent XSC exists for the synthesis of the primary cell wall of the eudicot Arabidopsis thaliana, consisting of IRX9L, IRX10L and IRX14. This would suggest the existence of distinct XSCs for primary and secondary cell wall xylan synthesis, reminiscent of the distinct cellulose synthesis complexes (CSCs) of the primary and secondary cell wall. In contrast to the CSC, in which each CESA protein has catalytic activity, the XSC seems to contain proteins with non-catalytic function with each component bearing potentially unique but crucial roles. Moreover, the core XSC formed by a combination of IRX9/IRX9L, IRX10/IRX10L and IRX14/IRX14L might not be stable in its composition during transit from the endoplasmic reticulum to the Golgi apparatus. Instead, potential dynamic changes of the XSC might be a means of regulating xylan biosynthesis to facilitate coordinated deposition of tailored polysaccharides in the plant cell wall

Survival improvement conferred by the Pseudoalteromonas sp. NC201 probiotic in Litopenaeus stylirostris exposed to Vibrio nigripulchritudo infection and salinity stress

This study aimed to investigate the potential protection conferred by the probiotic strain NC201 against biotic and abiotic stresses in Pacific blue shrimp Litopenaeus stylirostris that had received the probiotic throughout their lives. The presence of NC201 in shrimp hemolymph was investigated over the course of 24 h, before exposure to bacterial or physical stress. Results showed that NC201 had invaded the shrimp hemolymph 2 h following administration, but had completely disappeared by 48 h. NC201 identification through morphotype observation was confirmed by MALDI-TOF biotyping and results also indicated that NC201 and Pseudoalteromonas piscicida are closely related. A challenge by immersion was carried out on subadults using Vibrio nigripulchritudo at 105 CFU/ml. Cumulative mortality was two-fold lower in the treated group (24%) than in the control group (48%) at 144 h post infection. The probiotic in the shrimp hemolymph was diminished in infectious conditions compared with non-infectious ones and V. nigripulchritudo prevalence was simultaneously lower in animals treated with NC201. The relative expression of genes coding lysozyme and penaeidin 3 was evaluated 24 h post infection and their transcript numbers were found to be lower in probiotic animals than in control animals for both genes. Hyposaline stress was also used to evaluate the benefits of NC201 treatment on early juveniles and subadults. At low salinities, animals showed an increased survival rate when treated with NC201, by 10 and 17.5% at 48 h post stress, respectively. Moreover, in subadults treated with the probiotic, a better recovery of the plasmatic osmolality was observed. All these results confirm that NC201 is a good candidate probiotic for shrimp aquaculture