The Quality and Bacterial Community Changes in Freshwater Crawfish Stored at 4 °C in Vacuum Packaging

Abstract

Crawfish can be easily spoiled due to their rich nutrition and high water content, which is difficult to preserve. In this study, the dominant spoilage organisms in crawfish which were stored at 4 °C in vacuum packaging were identified by high-throughput sequencing technology; after sequencing the full-length 16S rRNA gene, the changes in the bacterial community structure, diversity and quality (texture, flavor, etc.) were analyzed. Our results reflected that the specific spoilage organisms (SSOs) of crawfish were Aeromonas sobria, Shewanella putrefaciens, Trichococcus pasteurii and Enterococcus aquimarinus, since their abundances significantly increased after being stored for 12 days at 4 °C under vacuum conditions. At the same time, the abundance and diversity of the microbial community decreased with storage time, which was related to the rapid growth of the dominant spoilage organisms and the inhibition of other kinds of microorganisms at the end of the spoilage stage. Function prediction results showed that the gene which contributed to metabolism influenced the spoilage process. Moreover, the decline in texture of crawfish was negatively correlated to the richness of SSOs; this may be because SSOs can produce alkaline proteases to degrade the myofibrillar protein. On the contrary, the unpleasant flavor of crawfish, resulting from volatile flavor compounds such as S-containing compounds and APEOs, etc., is negatively correlated to the richness of SSOs, due to the metabolism of SSOs by secondary metabolites such as terpenoids, polyketides and lips, which can lead to decarboxylation, deamination and enzymatic oxidation. These results are very important to achieve the purpose of targeted inhibition of crawfish spoilage at 4 °C in vacuum packaging.

Diversity of the protease-producing bacteria and their extracellular protease in the coastal mudflat of Jiaozhou Bay, China: in response to clam naturally growing and aquaculture

“…Lutibacter was reported to be predominant in shallow water marine sediment (Kerfahi et al, 2014), and some strains have been isolated from tidal flat sediments (Choi and Cho, 2006). However, except for a Trichococcus pasteurii strain that was isolated from freshwater crawfish and has been reported to produce alkaline proteases to degrade the myofibrillar protein (Qiu et al, 2022), no other studies report on the protease-producing ability of these four genera. What is different is the Psychrobacter genus.…”

Comparison of the gut microbiota and metabolism in different regions of Red Swamp Crayfish (Procambarus clarkii)

“…Aeromonas made up a sizable amount of the bacteria in the HB group. Aeromonas are the main disease-producing bacteria in freshwater creatures (Qiu et al, 2022). Aeromonas infection of fish easily causes symptoms such as sepsis, enteritis, skin ulceration, and necrosis, such as Pelodiscus sinensis and Betta splendens Regan (Purivirojkul, 2012;Lv et al, 2021).…”

Growth Reduction of Vibrionaceae and Microflora Diversity in Ice-Stored Pacific White Shrimp (Penaeus vannamei) Treated with a Low-Frequency Electric Field

“…The observed species, Chao 1, and Ace indexes were used to assess the abundance of microbial communities. The Shannon and Simpson indexes reflect the diversity of the community and the concentration of dominant species, respectively [34]. As shown in Table 1, compared to the XY group, the Observed species, ACE, and Chao1 indexes decreased, while the Shannon and Simpson indexes increased in the B group.…”