Akiyama, D. | Search bioRxiv

bioRxiv2026

Non-linear growth models combined with survival rates identify the optimal rearing temperature and harvest timing in edible crickets, Gryllus bimaculatus and Teleogryllus occipitalis

Crickets are gaining attention as sustainable protein sources because of their high nutritional value and low environmental impact. Growth models are essential tools for optimising production by predicting growth characteristics. However, previous studies have not compared multiple non-linear growth models for crickets or explicitly considered environmental factors. We analysed the growth patterns of the two-spotted cricket (Gryllus bimaculatus) and the Asian cricket (Teleogryllus occipitalis) at multiple temperatures (25.0, 27.5, 30.0, 32.5 and 35.0 {degrees}C) using three non-linear models (Gompertz model, logistic model, and von Bertalanffy model) and combined the predicted body mass with observed survival rates to predict the optimal harvest time and temperature. All three models fitted the data well (R2 [≥] 0.97 in both species). The asymptotic body mass was highest at 30.0 {degrees}C, and the growth rate constant increased with temperature, reaching its maximum at 35.0 {degrees}C except for the logistic model in G. bimaculatus (32.5 {degrees}C). In addition, the predicted value of harvest, calculated by combining predicted body mass and observed survival probability, was highest at 30.0 {degrees}C in both species, reaching 13.82 kg/m3 at 38 days in G. bimaculatus and 7.12 kg/m3 at 62 days in T. occipitalis. These results suggest that 30.0 {degrees}C is the most suitable constant-temperature condition for maximising predicted productivity, although the optimal harvest timing differs between species.

physiology↗

bioRxiv2022

Secondary metabolites produced during Aspergillus fumigatus and Pseudomonas aeruginosa biofilm formation

In Cystic Fibrosis (CF), mucus plaques are formed in the patients lung, creating a hypoxic condition and a propitious environment for colonization and persistence of many microorganisms. There is clinical evidence showing that Aspergillus fumigatus can co-colonize CF patients with Pseudomonas aeruginosa, which has been associated with lung function decline. P. aeruginosa produces several compounds with inhibitory and anti-biofilm effects against A. fumigatus in vitro; however, little is known about the fungal compounds produced in counterattack. Here, we annotated fungal and bacterial secondary metabolites (SM) produced in mixed biofilms in normoxia and hypoxia conditions. We detected nine SMs produced by P. aeruginosa. Phenazines and different analogs of pyoverdin were the main compounds produced by P. aeruginosa, and their secretion were increased by the fungal presence. The roles of the two operons responsible for phenazines production (phzA1 and phzA2) were also investigated showing both mutants are able to produce partial sets of phenazines. We detected a total of 20 SMs secreted by A. fumigatus either in monoculture or in co-culture with P. aeruginosa. All these compounds are secreted during biofilm formation either in normoxia or hypoxia. However, only eight compounds (demethoxyfumitremorgin C, fumitremorgin, ferrichrome, ferricrocin, tricetylfusigen, gliotoxin, gliotoxin E, and pyripyropene A) were detected during the biofilm formation by the co-culture of A. fumigatus and P. aeruginosa upon both normoxia and hypoxia conditions. Overall, we showed how diverse is SM secretion during A. fumigatus and P. aeruginosa mixed culture and how this can affect biofilm formation both in normoxia and hypoxia. Author SummaryThe interaction between Pseudomonas aeruginosa and Aspergillus fumigatus has been well-characterized in vitro. In this scenario, the bacterium exerts a strong inhibitory effect against the fungus. However, little is known about the metabolites produced by the fungus to counterattack the bacteria. Our work aimed to annotate secondary metabolites (SM) secreted during co-culture between P. aeruginosa and A. fumigatus during biofilm formation in both normoxia and hypoxia. The bacterium produces several different types of phenazines and pyoverdins, in response to the fungus presence. In contrast, we were able to annotate 29 metabolites produced during A. fumigatus biofilm formation but only eight compounds were detected during biofilm formation by the co-culture of A. fumigatus and P. aeruginosa upon both normoxia and hypoxia. In conclusion, we have detected many SMs secreted during A. fumigatus and P. aeruginosa biofilm formation. This analysis can provide several opportunities to understand the interaction between these two species.

microbiology↗