Does Ralstonia eutropha, rich in poly‐β hydroxybutyrate (PHB), protect blue mussel larvae against pathogenic vibrios?

Abstract

The natural amorphous polymer poly‐β‐hydroxybutyrate (PHB‐A: lyophilized Ralstonia eutropha containing 75% PHB) was used as a biological agent to control bacterial pathogens of blue mussel (Mytilus edulis) larvae. The larvae were supplied with PHB‐A at a concentration of 1 or 10 mg/L for 6 or 24 hr, followed by exposure to either the rifampicin‐resistant pathogen Vibrio splendidus or Vibrio coralliilyticus at a concentration of 105 CFU/ml. Larvae pretreated 6 hr with PHB‐A (1 mg/L) survived a Vibrio challenge better relative to 24 hr pretreatment. After 96 hr of pathogen exposure, the survival of PHB‐A‐treated mussel larvae was 1.41‐ and 1.76‐fold higher than the non‐treated larvae when challenged with V. splendidus and V. coralliilyticus, respectively. Growth inhibition of the two pathogens at four concentrations of the monomer β‐HB (1, 5, 25 and 125 mM) was tested in vitro in LB35 medium, buffered at two different pH values (pH 7 and pH 8). The highest concentration of 125 mM significantly inhibited the pathogen growth in comparison to the lower levels. The effect of β‐HB on the production of virulence factors in the tested pathogenic Vibrios revealed a variable pattern of responses.

Scientific Opinion on the update of the list of QPS‐recommended biological agents intentionally added to food or feed as notified to EFSA (2017–2019)

“…C. necator is used as source of polyhydroxybutyrate (PHB) which can be used for the production of bioplastics after recovery from the cell cytoplasm (Aramvash et al., ) or by using the dried biomass (Kunasundari et al., ). PHBs and the dried biomass of C. necator can be used for its antimicrobial, insecticidal and antiviral activities based on the degradation by bacteria of PHB into β‐Hydroxybutyrate (van Hung et al., ). C. necator has been genetically modified to produce several compounds such as isopropanol, hydrocarbons, methyl ketones, free fatty acids, alkanes etc.…”

Update of the list of QPS‐recommended biological agents intentionally added to food or feed as notified to EFSA 11: suitability of taxonomic units notified to EFSA until September 2019

“…C. necator is used as source of polyhydroxybutyrate (PHB) which can be used for the production of bioplastics after recovery from the cell cytoplasm (Aramvash et al, 2015) or by using the dried biomass (Kunasundari et al, 2013). PHBs and the dried biomass of C. necator can be used for its antimicrobial, insecticidal and antiviral activities based on the degradation by bacteria of PHB into b-hydroxybutyrate (van Hung et al, 2019). C. necator has been genetically modified to produce several compounds as isopropanol, hydrocarbons, methyl ketones, free fatty acids, alkanes etc.…”

An Eco-Friendly Conversion of Aquaculture Suspended Solid Wastes Into High-Quality Fish Food by Improving Poly-β-Hydroxybutyrate Production

“…Dietary PHB supplementation can up-regulate the mRNA expression of some immune-related genes such as Hsp70, MHCs, TLRs, IL-8, hepcidin, pbpA, and AOX in fish (Qiao et al, 2019a(Qiao et al, , 2020. Additionally, PHB can enhance the disease resistance of aquatic animals against both bacterial and viral infections (Deng et al, 2014;Defoirdt et al, 2018;Van Hung et al, 2019;Qiao et al, 2020). In the present study, PHB-enriched SS can be up-taken by gibel carp, which is in accordance with the previous studies which confirmed that SS can be up-taken by omnivorous fish and shrimp (Nhan et al, 2010;Meirong et al, 2018;Wu et al, 2018;Zhang et al, 2018).…”