Comparative Profiling of Survival, Growth, and Intestinal Microbial Community of Pearl Oyster Pinctada maxima Juvenile in the Industrial Farming: The Feasibility of Using Spray-Dried Microalgae Powder

Abstract

Industrial farming is an alternative mode for Pinctada maxima juvenile cultivation to avoid mass mortality caused by natural disasters. Suitable and enough food is crucial for successful industrial bivalve farming. To investigate the feasibility of live microalga instead of spray-dried microalgal powder in P. maxima juvenile industrial farming, this study replaces a positive control live microalgal diet [Isochrysis zhanjiangensis (L-iso) and Platymonas subcordiformis (L-pla)] with spray-dried I. zhanjiangensis powder (P-iso) and P. subcordiformis powder (P-pla). Continuous feeding trials (30 days) were conducted on the P. maxima juvenile (1.2008 ± 0.0009 g initial weight and 30.12 ± 0.05 mm initial shell length), under laboratory conditions. Survival, growth performance, and intestinal microbial community were studied and compared across the groups. Results showed that survival rate (SR) did not differ significantly across the groups (ranged from 84 to 86%, P > 0.05). The growth performance in spray-dried microalgal groups, including total weight (TW), shell height (SH), absolute growth rate (AGR), and relative growth rate (RGR) for SH and TW, was slightly lower than that in live microalgal groups, while the activities of pepsin (PES), amylase (AMS), and lipase (LPS) were significantly higher (P < 0.05). The best growth performance was observed in the L-iso group, followed by the L-pla group. A 16S rRNA-based sequencing revealed that Proteobacteria was the dominant phylum in P. maxima juvenile intestinal bacterial community under controlled conditions, which accounted for 62–82% across groups. The intestinal bacteria at the genus level were more sensitive to diets, whereas Burkholderia was the dominant genus in both L-iso (66.52 ± 6.43%) and L-pla groups (54.00 ± 5.66%), while Mycoplasma, Alphaproteobacteria, and Oxyphotobacteria were in both P-iso and P-pla groups. The P-pla group got higher ACE, Chao1, and Simpson and Shannon indices (P < 0.05). The above results suggested that the spray-dried P-iso and P-pla can serve as substitutes for live microalga in P. maxima juvenile industrial farming under controlled conditions. The finding in this study provides basic data to optimize industrial farming technology and healthy management for P. maxima juvenile.

Comparative Effects of Microalgal Species on Growth, Feeding, and Metabolism of Pearl Oysters, Pinctada fucata martensii and Pinctada maxima

“…When comparing the energy budget parameters, the CRs of two pearl oyster species significantly increased, from 0.58-1.82 L•h -1 •g -1 to 1.75-3.60 L•h -1 •g -1 for P. f. martensii and from 0.25-1.62 L•h -1 •g -1 to 1.00-2.78 L•h -1 •g -1 for P. maxima, respectively. The CRs in P. f. martensii and P. maxima were almost the same as in the previous studies by Yukihira et al (1998); Zhang et al (2021), andYang et al (2021). Furthermore, the RRs and ARs of each pearl oyster species decreased with the increase in size, which was detected in other bivalve species, such as green-lipped mussel and pacific oyster (Tamayo et al, 2014;Ibarrola et al, 2017).…”

“…The higher growth rates in P. f. martensii might be ascribed to the relatively higher adaptability to complex and volatile environments than those in P. maxima. P. maxima prefers to live in the oligotrophic tropical waters of coral reefs and atolls, while P. f. martensii prefers to live in coastal areas of higher latitudes and is more tolerant to extreme temperature and nutrient inputs (Yang et al, 2021;Zhang et al, 2021). The natural diets for pearl oysters were more complex than artificial diets.…”

“…Until now, the causes of the high mortality rate of P. maxima are ascribed to diseases, environmental degradation, micro-algal composition, and so on (Pass et al, 1987;Taylor et al, 2004;Kvingedal et al, 2010;Crockford and Jones, 2012;Deng et al, 2013a andDeng et al, 2013b). In our previous study, a higher clearance rate (CR) and growth rate in P. f. martensii were observed compared to P. maxima fed with Isochrysis galbana (Yang et al, 2021;Zhang et al, 2021). We inferred that the lower CR and feed conversion ratio (FCR) to microalgae caused a low growth rate in P. maxima.…”

Growth and nutritional health of Pterophyllum scalare juveniles: Unleashing the benefits of feeding with Artemia sp. in aquariums

“…The enzymes AMS, PES, and LPS are often used as indicators of living organisms' physiological status, digestive processes, and nutritional condition. 18 The feed and feeding modes, especially the food type and its component, are the key factors affecting the activities of digestive enzymes. 19 In the present study, P. scalare juveniles were fed a diet supplemented with Artemia sp.…”

Enzyme activities and gene expression in digestion and metabolism of Hyriopsis cumingii under different temperature and diet ration

“…The application of massive organic fertilizers to cultivate microalgae causes mussel diseases and environmental pollution in the traditional cultivation mode of H. cumingii (Hu et al, 2015b). Nowadays, industrial aquaculture is a way to achieve ecological cultivation, and the exploration of suitable farming conditions is the key to control breeding costs and realize high production (Yang et al, 2022). Therefore, there is an urgent need in nding e cient microalgae diets and determining the optimal ration level at the speci c temperature to optimize the economic and environmental bene ts of H. cumingii cultivation.…”