Biology subjects

Kortner, T. M.

Publications and source records attributed to Kortner, T. M..

3 recordsLinked to original sources

bioRxiv2026

Feed Composition and Antibiotic Supplements Modulate Digestive Enzyme Activities and Alter Gut Microbiome of Pacific White Shrimp

The transition from fishmeal to sustainable alternatives in aquaculture is essential, however the physiological and microbial impacts of alternative diets in shrimp remain poorly understood. Here, we examine how substituting fishmeal with plant-based proteins such as guar and soybean meals, the inclusion of feather meal, and the use of a commonly used antibiotic (gentamicin) influence digestive enzyme function, protein digestibility, and gut microbial assemblages in Litopenaeus vannamei (Pacific white shrimp). The guar-based diet notably altered gut microbiota composition and decreased leucine aminopeptidase activity while maintaining high protein digestibility (>90%). In contrast, the soya/feather diet caused greater disruption to enzyme activity and microbial communities, resulting in reduced digestibility ([~]75%). The gent/guar diet showed comparable digestibility and microbial stability to the guar diet, with only minor shifts at the genus level. Although digestibility data for the acclimation diet were unavailable, these findings highlight diet-specific physiological and microbial responses to fishmeal substitutes. This emphasizes the need to consider dietary formulation, digestive function, and microbiome dynamics when developing sustainable aquafeeds for shrimp farming. ImportanceThe Pacific white shrimp (Litopenaeus vannamei) is a cornerstone of global aquaculture, yet optimizing its diet remains challenging. Current shrimp farming heavily depends on fishmeal, an unsustainable protein source, and antibiotic use to maintain shrimp health raises concerns about antimicrobial resistance and environmental impacts. This study highlights how alternative dietary formulations, including plant-based proteins and antibiotic supplements, influence shrimp digestive physiology and reshape gut microbiomes. Understanding these interactions is crucial to developing feed formulations that support robust shrimp growth and health without excessive reliance on antibiotics or fishmeal. By demonstrating how specific dietary ingredients affect both shrimp digestion and beneficial gut bacteria, this research provides valuable insights that can inform sustainable and responsible shrimp aquaculture practices globally.

microbiology↗

bioRxiv2021

Consistent changes in the intestinal microbiota of Atlantic salmon fed insect meal diets

Being part of fishs natural diets, insects have become a realistic, sustainable feed ingredient for aquaculture. While nutritional values of insects have been extensively studied in various fish species, their impact on the fish microbiota remains to be fully explored. In an 8-week freshwater feeding trial, Atlantic salmon (Salmo salar) were fed either a commercially relevant reference diet or an insect meal diet wherein black soldier fly (Hermetia illucens) larvae meal comprised 60% of total ingredients. Microbiota of digesta and mucosa origin from the proximal and distal intestine were collected and profiled along with feed and water samples. The insect meal diet markedly modulated the salmon intestinal microbiota. Overall, the microbial diversity was lower in the digesta of salmon fed the insect meal diet but higher in the mucosa. A group of bacterial genera, dominated by members of the Bacillaceae family, was enriched in salmon fed the insect meal diet, which confirms our previous findings in a seawater feeding trial. We also found that microbiota in the intestine closely resembled that of the feeds but was distinct from the water microbiota. Notably, bacterial genera associated with the diet effects were present in the feeds as well. In conclusion, our results show consistent changes in the intestinal microbiota of Atlantic salmon fed diets containing black soldier fly larvae meal.

microbiology↗

bioRxiv2020

Differential Response of Digesta- and Mucosa-Associated Intestinal Microbiota to Dietary Black Soldier Fly (Hermetia illucens) Larvae Meal in Seawater Phase Atlantic Salmon (Salmo salar)

Intestinal digesta is commonly used for studying responses of microbiota to dietary shifts, yet evidence is accumulating that it represents an incomplete view of the intestinal microbiota. In a 16-week seawater feeding trial, Atlantic salmon (Salmo salar) were fed either a commercially-relevant reference diet or an insect meal diet containing 15% black soldier fly (Hermetia illucens) larvae meal. The digesta- and mucosa-associated distal intestinal microbiota were profiled by 16S rRNA gene sequencing. Regardless of diet, we observed substantial differences between digesta- and mucosa-associated intestinal microbiota. Microbial richness and diversity were much higher in the digesta than the mucosa. The insect meal diet altered the distal intestinal microbiota resulting in higher microbial richness and diversity. The diet effect, however, depended on the sample origin. Digesta-associated intestinal microbiota showed more pronounced changes than the mucosa-associated microbiota. Lastly, multivariate association analyses identified two mucosa-enriched taxa, Brevinema andersonii and unclassified Spirochaetaceae, associated with the expression of genes related to immune responses and barrier function in the distal intestine, respectively. Overall, our data clearly indicate that responses in digesta- and mucosa-associated microbiota to dietary inclusion of insect meal differ, with the latter being more resilient to dietary changes.

microbiology↗