Total Protease Activity Research Articles

Growth Performance, Digestive Enzyme Activities, and Oxidative Stress Markers in the Proximal Intestine of European Sea Bass (Dicentrarchus labrax) Fed High Starch or Lipid Diets

The effect of different main dietary compositions on growth, anticipatory digestive enzyme activities, and oxidative status was studied in the proximal intestine of juvenile European sea bass. A control diet (C, 44% protein, 17.6% lipid, and 20% starch), three diets with increasing starch levels to test protein sparing (P36S36, P40S29, and P43S24), and two diets with high lipid content (L20S13 and L22S7) were tested. After 20 weeks, growth, digestive enzyme activities, lipid peroxidation, antioxidant enzyme activities, and G6PDH activity were measured after a 24-h fast. Sea bass fed P43S24 and L20S13 maintained an oxidative status like C fish, up-regulated CAT activity, and adjusted anticipatory protease activity. Instead, the lipid peroxidation increased in the L22S7 group, although CAT activity increased, whereas anticipatory total protease activity was downregulated. P40S29 also triggered LPO and CAT activity, but G6PDH levels diminished significantly. Moreover, an up-regulation in digestive enzyme activities was found. Finally, P36S36 fish showed less antioxidant enzyme activity and G6PDH, although their LPO tended to increase and their lipase and α-amylase activities were upregulated. In conclusion, the inclusion of carbohydrates up to 24% or lipids up to 20% is possible for this species if protein requirements are met without negative effects on growth.

Studies on the growth, immunomodulation and gut morphometry of Labeo rohita fed pectin

<br />The present study was designed to evaluate the effect of pectin supplemented feeds on the growth, gut morphology and immunology of <i>Labeo rohita</i>. Experimental feeds containing various concentrations of pectin including control (0%), T1 (0.5%), T2 (1.0%), T3 (2.0%), and T4 (4.0%) were administered to <i>L. rohita</i> twice per day at a rate of 3% body weight. There was a significant (<i>P</i> < 0.05) decrease in average final weight, weight gain%, net weight gain and specific growth rate observed in treatment groups in order of control > T1 > T2 > T3 > T4 while feed conversion ratio was significantly (<i>P </i>< 0.05) higher in T4 compared to the other groups T3 > T2 > T1 > control. Immunological parameters of peroxidase, protease and antiprotease (trypsin) showed significant (<i>P </i>< 0.05) results between control and treated groups. Peroxidase activity was significantly (<i>P </i>< 0.05) higher in T4 group fish compared to T3 > T2 > T1 > control group. Total protein, protease and antiprotease activity were significantly (<i>P </i>< 0.05) higher in the control compared to treatment groups T1 > T2 > T3 > T4. An increased level of the non-starch polysaccharide pectin in feed caused acute effects on gut morphometry. Villus length, villus width, and an increase in mucosal folds were abnormal but no significant (<i>P</i> > 0.05) abnormality was observed in the control group. In the submucosal part of the intestine, hyperplasia was shown in loose connective tissues and in adipose tissue cells in the treated groups. In conclusion, dietary pectin supplementation from 0.5% to 4% had negative effects on the growth, immunological parameters and gut histomorphology of <i>L. rohita</i>.

Differential deuterolysin expression with a peak at low pH in human pathogenic fungi Trichophyton rubrum and T. mentagrophytes.

Trichophyton rubrum and T. mentagrophytes are the most common agents of dermatomycosis, a disease affecting millions worldwide. It has been widely recognized that secreted proteases are a key factor for host colonization. Dermatophytes have an unusually high amount of secreted protease, differentially expressed, and influenced by various conditions. This study analyzed the rule and expression of secreted deuterolysin protease of the M35 protein family in these two representative dermatophyte species. All strains secreted protease and could grow on keratin as the sole carbon and nitrogen source. Adding glucose to the keratin medium reduced the growth rate. Deuterolysin genes were most strongly expressed at acid conditions. NPIIc and NPIId expression was significantly higher than the other three deuterolysins. NPIIc had a high expression level in the two T. rubrum strains but a low expression in T. mentagrophytes strains. Both T. mentagrophytes strains had a high NPIId expression at low pH. NPIIc and NPIId deletion in T. rubrum caused a minor reduction in total protease activity, indicating the redundancy of protease in dermatophytes. It was postulated that protease gene enrichment in dermatophytes allows a sophisticated regulation of protease secretion to cope with changing conditions.

Dietary Lactobacillus helveticus and Gum Arabic improves growth indices, digestive enzyme activities, intestinal microbiota, innate immunological parameters, antioxidant capacity, and disease resistance in common carp

The present study aimed at determining the effects of Lactobacillus helveticus (LH), Gum Arabic (GA; natural prebiotic), and their combination as synbiotic on growth performance, digestive enzymes activity, gut microbiota, innate immunity status, antioxidant capacity, and disease resistance against Aeromonas hydrophyla in common carp, Cyprinus carpio for 8 weeks. For this, 735 common carp juveniles (Mean ± standard deviation; 22.51 ± 0.40 g) were fed with 7 different diets including basal diet (C), LH1 (1 × 107 CFU/g), LH2 (1 × 109 CFU/g), GA1 (0.5%), GA2 (1%), LH1+GA1 (1 × 107 CFU/g + 0.5%), and LH2+GA2 (1 × 109 CFU/g + 1%) for 8 weeks. Dietary supplementation with GA and/or LH significantly increased growth performance, WBC, serum total immunoglobulin, superoxide dismutase and catalase activities, skin mucus lysozyme and total immunoglobulin and intestinal lactic acid bacteria. Whereas there were significant improvements in various parameters tested in different treatments, the highest improvement in growth performance, WBC, monocyte/neutrophil percentages, serum lysozyme, alternative complement, glutathione peroxidase and malondialdehyde, skin mucosal alkaline phosphatase, protease, and immunoglobulin, intestinal total bacterial count, protease and amylase activities were observed in the synbiotic treatments, particularly LH1+GA1. After an experimental infection with Aeromonas hydrophila, all experimental treatments exhibited significantly higher survival, compared to the control treatment. The highest survival was related to the synbiotic (particularly LH1+GA1), followed by prebiotic, and probiotic treatments. Overall, synbiotic containing 1 × 107 CFU/g LH + 0.5% GA can improve growth rate and feed efficiency in common carp. Moreover, the synbiotic can improve the antioxidant/innate immune systems and dominate lactic acid bacteria in the fish intestine that may be the reasons of the highest resistance against A. hydrophila infection.

A meta-analysis for assessing the contributions of trypsin and chymotrypsin as the two major endoproteases in protein hydrolysis in fish intestine

For the majority of fish species, regardless of being gastric or agastric, trypsin and chymotrypsin are known as the two main alkaline proteases responsible for the initial stage of protein hydrolysis in the fish intestine. Although the critical role of these proteases for protein hydrolysis in fish intestine is without doubt, the relative input of each enzyme in protein hydrolysis is still unclear. Data used in the present study has been retrieved from a bibliographic search using the Dimensions application (https://app.dimensions.ai/discover/publication tool). Retrieved articles were carefully inspected to identify whether they contained the description of the development of ontogenetic activities for trypsin, chymotrypsin, and total alkaline proteases in fish intestine. From the list of consulted articles, 21 studies were chosen based on correlation coefficients (Pearson correlation test), and four groups of fish were identified with high significant correlation between 1) the activity of chymotrypsin and total alkaline proteases; 2) the activity of trypsin, chymotrypsin, and total alkaline proteases; 3) the activity of trypsin and total alkaline proteases, and 4) mainly negative correlation between trypsin, chymotrypsin, and total alkaline proteases. These results indicated that the relative inputs of trypsin and chymotrypsin in protein hydrolysis may vary significantly among different fish species, which is a crucial point for proper understanding of species-specific digestive traits in both natural and aquaculture scenarios.

Modified N-acyl-L-homoserine lactone compounds abrogate Las-dependent quorum-sensing response in human pathogen Pseudomonas aeruginosa.

Quorum sensing (QS) is a mode of cell-cell communication that bacteria use to sense population density and orchestrate collective behaviors. The common opportunistic human pathogen Pseudomonas aeruginosa employs QS to regulate a large set of genes involved in virulence and host-pathogen interactions. The Las circuit positioned on the top of the QS hierarchy in P. aeruginosa makes use of N-acyl-L-homoserine lactones (AHLs) as signal molecules, like N-3-oxo-dodecanoyl-L-homoserine lactone (3O-C12-HSL). Disabling QS circuits by certain small-molecule compounds, known as quorum-sensing inhibitors (QSIs), has been proposed as a strategy to attenuate bacterial pathogenicity. In this study, four new AHL analogs were designed by incorporating a tert-butoxycarbonyl Boc group in amide and β-keto (3-oxo) moiety. Compounds were evaluated on a molecular and phenotypic basis as a QSI using the screening strategy linked to the assignment of the Las QS system in P. aeruginosa. Using a LasR-based bioreporter, we found that the compounds decreased LasR-controlled light activity and competed efficiently with natural 3O-C12-HSL. The compounds reduced the production of the cognate 3O-C12-HSL and certain virulence traits, like total protease activity, elastase activity, pyocyanin production, and extracellular DNA release. Furthermore, a quantitative proteomic approach was used to study the effect of the compounds on QS-regulated extracellular proteins. Among the four compounds tested, one of them showed the most significant difference in the appearance of the 3O-C12-HSL-responsive reference proteins related to QS communication and virulence, i.e., a distinct activity as a QSI. Moreover, by combining experimental data with computational chemistry, we addressed the effect of LasR protein flexibility on docking precision and assessed the advantage of using a multi-conformational docking procedure for binding mode prediction of LasR modulators. Thus, the four new AHL compounds were tested for their interaction with the AHL-binding site in LasR to identify the key interferences with the activity of LasR. Our study provides further insight into molecular features that are required for small-molecule modulation of LasR-dependent QS communication in P. aeruginosa. This should facilitate rational design of the next generation of antivirulence tools to study and manipulate QS-controlled fitness in bacteria and, thereby, handle bacterial infections in a new way.

Heterologous expression of quorum sensing transcriptional regulator LitR and its function in virulence-related gene regulation in foodborne pathogen Aeromonas hydrophila.

Aeromonas hydrophila is an important foodborne and zoonoticpathogen causing serious diseases. Hence, revealing thepathogenicmechanism of A. hydrophila will be of importance in the development of novel therapies. Aeromonas hydrophila litR was reported to be regulated by two quorum sensing (QS) pathways, indicating that it is involved in QS network regulation correlated with bacterial virulence. However, the function of LitR is currently not understood. Therefore, we aimed to reveal the potential regulatory mechanisms of LitR on virulence-related genes. In this study, amino acid sequences analysis of LitR was conducted, providing bioinformatics evidence for its function as a potential transcriptional regulator. LitR protein was heterologous expressed, purified and its in-vitro multimeric forms were observed with gel filtration chromatography. The correlation between intracellular LitR expression level and cell density was analyzed with immunoblots. Regulation mechanisms of LitR on several important virulence-related factors were investigated with qRT-PCR, EMSA, DNase I footprinting and microscale thermophoresis binding assays, etc. Results showed that recombinant LitR protein aggregated mainly as dimer and hexamer in vitro. Intracellular expression level of LitR was positively correlated with cell density of A. hydrophila. Furthermore, LitR exhibited complicated regulation modes on virulence-related genes; it could directly bind to promoter regions of the hemolysin, serine protease and T6SS effector protein VgrG encoded genes. The promoter region of the hemolysin gene showed high binding affinity and mainly two binding sites for LitR. Different dissociation constants were obtained for LitR interaction with the hemolysin gene binding motifs I and II. Assays focusing on physiological characteristics of A. hydrophila prove that LitR positively regulated hemolytic and total extracellular protease activities. This study investigated the function of LitR as a quorum sensing transcriptional regulator in regulation of virulence-related genes, which will help reveal the mechanisms of A. hydrophila pathogenicity. LitR could serve as a potential target for development of new antimicrobial agents from the perspective of QS regulation.

Soil quality and r – K fungal communities in plantations after conversion from subtropical forest

Intensive clear-cutting of natural forests and conversion to monoculture plantations are ongoing worldwide, leading to the degradation of soil quality and microbial functions. Here, we compared soil quality index (SQI) and fungal communities in a natural forest (Forest) and four 5-year-old monoculture plantations, including Camellia oleifera (Oil), Amygdalus persica (Peach), Myrica rubra (Berry) and Cunninghamia lanceolate (Fir) in a subtropical region of China. After conversion, soil pH in the plantations rose up to 0.31, but organic carbon and total nitrogen contents, sucrase, acid protease, glutaminase, acid and alkaline phosphatase activities decreased by 83%, 59%, 40%, 64%, 66%, 94% and 59%, respectively. Correspondingly, the SQI dropped by 65%. High-throughput sequencing of the ITS1 region demonstrated an increase in α-diversity and a striking difference in β-diversity of fungi following conversion. Changes in the dominant fungal taxa following forest conversion to plantations were interpreted by r- and K-selection of life strategies. Conversion increased the fungal groups with r-strategies, such as Ascomycota and Zygomycota, but decreased the fungal groups with K-strategies, such as Basidiomycota. Genera affiliated to those phyla including Pseudophialophora, Rhytisma increased, but Russula decreased. Redundancy analysis and structural equation modeling indicated that the diversity and composition of fungal communities changed with soil degradation, which was mainly driven by increased pH and total phosphorus content, but decreased C/N ratio and C and N related enzymes activities. Overall, the conversion of forest to monoculture plantations decreased soil quality and the abundance of K-strategists, retarded the decomposition of persistent organic matter, but boosted the prevalence of r-strategists in a more diverse fungal community.

Стимулювання системи протеїназа-інгібітор протеїназ у результаті імерсійної гіпотермії

The effect of immersion hypothermia (IН) on proteolysis activity in adult male rats, which was performed at 0 °C for 5 min in the “forced swimming” test, studied; the body temperature decreased to 27.5 ± 0.5°C. In blood serum and non-nuclear fractions of homogenates of cerebral cortex, hypothalamus, cerebellum, brainstem, lungs, heart, liver and kidneys tissues were determined the total proteinase activity (TPA), non-trypsin-like proteinases (NTPs), such as chymase, prostate-specific antigen, partially tonin, kallikrein rK9, as well as trypsin-inhibitory activity of α-1-proteinase inhibitor (α-1-PI), α-2-macroglobulin (α-2-MG) by highly sensitive (10-9–10-10 g) enzymatic methods. It is noted that IH led to the TPA increase in all studied tissues (4-84 times), which corresponds to the psycho-emotional effects and the phenomenon of hormesis. After 24 h, TPA decreased, remaining above the control level, and in the kidneys increased further (90 times). NTLP activity as a result of IH increased in blood serum and cerebellum, decreased in the hypothalamus, and after 24 h increased further in serum (7 times), cerebellum, and heart. The activity of α-1-PI also increased in the brainstem, lungs, heart and kidneys, and decreased after 24 h in serum below the control level, and in the brainstem remained high, protecting against proteolytic attack. The activity of α-2-MG increased in the hypothalamus, heart, and cerebral cortex, maximum in the brainstem (2-5 times), and after 24 h - more significantly (24 times), but there were no changes in the cerebellum, where its initial level is the biggest. Thus, the development of IG as a result of swimming in cold water for 5 min at 0oC has a stimulating effect on the body and leads to a significant activation of the reactions of limited proteolysis.

Digestive Enzyme Activities in Barred Loach (Nemacheilus fasciatus, Val., 1846.): Effect of pH and Temperature

This study aims to determine the total protease, lipase, and amylase activities at different pHs, as well as pepsin and trypsin-like at different temperatures. A total of 240 individuals have been used in this study. Enzyme activity was measured by the spectrophotometer method. The effect of pH was evaluated on protease, lipase, and amylase activity, while the effect of temperature was evaluated on pepsin and trypsin-like activities.The results showed that the total protease activity at pH 7.0-10.0 was significantly higher than pH 1.7-5.0 (P &lt;0.05). Furthermore, the activity of lipase was significantly higher at pH 5.0-7.0 than pH 1.7, 3.4, and 10.0. Also, the activity of amylase at pH 7.0-8.0 was significantly higher (p &lt;0.05) than pH 1.7-5.0 and pH 10.0. Moreover, the pepsin-like activity in the anterior gut was significantly higher (p &lt;0.05) than the posterior gut.Conversely, trypsin-like activity in the posterior gut was significantly higher (p &lt;.05) than the anterior gut. Additionally, the pepsin-like activity was significantly higher at 45°C compared to different temperatures (p &lt;0.05), whereas trypsin-like was significantly (p &lt;0.05) higher at 60 °C than othertemperatures. Conclusively, the total protease and amylase activity was higher under neutral to slightly alkaline conditions, while lipase was higher under acidic to neutral conditions. Furthermore, the pepsin-like activity was only found in the anterior gut, whereas trypsin-like was higher in the posterior gut. The optimal temperature for pepsin-like and trypsin-like activity was 45 °C and 60 °C, respectively.

Individual and combined effects of the dietary Spirulina platensis and Bacillus licheniformis supplementation on growth performance, antioxidant capacity, innate immunity, relative gene expression and resistance of goldfish, Carassius auratus to Aeromonas hydrophila

This study evaluated the individual and combined effects of the dietary Spirulina platensis (SP) and probiotic bacterium Bacillus licheniformis (BL) on the growth performance, immune responses, and disease resistance in goldfish (Carassius auratus). A total of 216 fish (3.39 ± 0.24 g) were randomly distributed in 12 tanks with 18 fish per tank (4 treatments with 3 replications) and fed with diets containing 0% S. platensis and B. licheniformis (T0), 108 CFU/g B. licheniformis (T1), 2.5% S. platensis (T2), and 108 CFU/g B. licheniformis + 2.5% S. platensis (T3(. There were no significant differences in growth parameters. The alternative complement pathway (ACH50) and lysozyme activity were significantly increased in T2 and T3 treatments. No marked differences were observed in total immunoglobulin and protease activity among treatments (P > 0.05). The relative expression of IGF-1 was not affected by experimental diets (P > 0.05). Ghrelin gene showed significantly higher mRNA levels in fish fed with SP and BL (P < 0.05). The relative expression of catalase (CAT), and glutathione reductase (GSR) significantly increased in fish fed with the SP and BL (P < 0.05). No marked difference in glutathione peroxidase (GPX) gene expression was seen between the treatments (P > 0.05). The mRNA levels of lysozyme, IL6, IL-1β, TGF, and TNF2 transcription were higher in fish fed with SP and BL (P < 0.05). No notable difference was observed in TNF1 and IL10 gene expression between treatments (P > 0.05). Moreover, the result of the challenge test with A. hydrophila showed that goldfish fed with SP and BL had a lower mortality rate than the control. In conclusion, the supplementation of SP and BL can be used as feed additives to enhance disease resistance against A. hydrophila infection by stimulating the immune system in goldfish.

Identification of Proteases and Protease Inhibitors in Seeds of the Recalcitrant Forest Tree Species Quercus ilex.

Proteases and protease inhibitors have been identified in the recalcitrant species Quercus ilex using in silico and wet methods, with focus on those present in seeds during germination. In silico analyses showed that the Q. ilex transcriptome database contained 2,240 and 97 transcripts annotated as proteases and protease inhibitors, respectively. They belonged to the different families according to MEROPS,1 being the serine and metallo ones the most represented. The data were compared with those previously reported for other Quercus species, including Q. suber, Q. lobata, and Q. robur. Changes in proteases and protease inhibitors alongside seed germination in cotyledon and embryo axis tissues were assessed using proteomics and in vitro and in gel activity assays. Shotgun (LC–MSMS) analysis of embryo axes and cotyledons in nonviable (NV), mature (T1) and germinated (T3) seeds allowed the identification of 177 proteases and 12 protease inhibitors, mostly represented by serine and metallo types. Total protease activity, as determined by in vitro assays using azocasein as substrate, was higher in cotyledons than in embryo axes. There were not differences in activity among cotyledon samples, while embryo axis peaked at germinated T4 stage. Gel assays revealed the presence of protease activities in at least 10 resolved bands, in the Mr range of 60–260 kDa, being some of them common to cotyledons and embryo axes in either nonviable, mature, and germinated seeds. Bands showing quantitative or qualitative changes upon germination were observed in embryo axes but not in cotyledons at Mr values of 60–140 kDa. Proteomics shotgun analysis of the 10 bands with protease activity supported the results obtained in the overall proteome analysis, with 227 proteases and 3 protease inhibitors identified mostly represented by the serine, cysteine, and metallo families. The combined use of shotgun proteomics and protease activity measurements allowed the identification of tissue-specific (e.g., cysteine protease inhibitors in embryo axes of mature acorns) and stage-specific proteins (e.g., those associated with mobilization of storage proteins accumulated in T3 stage). Those proteins showing differences between nonviable and viable seeds could be related to viability, and those variables between mature and germinated could be associated with the germination process. These differences are observed mostly in embryo axes but not in cotyledons. Among them, those implicated in mobilization of reserve proteins, such as the cathepsin H cysteine protease and Clp proteases, and also the large number of subunits of the CNS and 26S proteasome complex differentially identified in embryos of the several stages suggests that protein degradation via CNS/26S plays a major role early in germination. Conversely, aspartic proteases such as nepenthesins were exclusively identified in NV seeds, so their presence could be used as indicator of nonviability.

Protease and DNase Activities of a Very Stable High-Molecular-Mass Multiprotein Complex from Sea Cucumber Eupentacta fraudatrix.

Only some human organs, including the liver, are capable of very weak self-regeneration. Some marine echinoderms are very useful for studying the self-regeneration processes of organs and tissues. For example, sea cucumbers Eupentacta fraudatrix (holothurians) demonstrate complete restoration of all organs and the body within several weeks after their division into two parts. Therefore, these cucumbers are a prospective model for studying the general mechanisms of self-regeneration. However, there is no data available yet concerning biomolecules of holothurians, which can stimulate the processes of organ and whole-body regeneration. Investigation of these restoration mechanisms is very important for modern medicine and biology because it can help to understand which hormones, nucleic acids, proteins, enzymes, or complexes play an essential role in self-regeneration. It is possible that stable, polyfunctional, high-molecular-weight protein complexes play an essential role in these processes. It has recently been shown that sea cucumbers Eupentacta fraudatrix contain a very stable multiprotein complex of about 2000 kDa. The first analysis of possible enzymatic activities of a stable protein complex was carried out in this work, revealing that the complex possesses several protease and DNase activities. The complex metalloprotease is activated by several metal ions (Zn2+ > Mn2+ > Mg2+). The relative contribution of metalloproteases (~63.4%), serine-like protease (~30.5%), and thiol protease (~6.1%) to the total protease activity of the complex was estimated. Metal-independent proteases of the complex hydrolyze proteins at trypsin-specific sites (after Lys and Arg). The complex contains both metal-dependent and metal-independent DNases. Mg2+, Mn2+, and Co2+ ions were found to strongly increase the DNase activity of the complex.

Salivary Assessments in Post-Liver Transplantation Patients.

Saliva is in the first line of the body’s defense mechanism. In order to better understand how liver transplantation impacts salivary biochemistry, the aim of this cross-sectional study was to explore variations of salivary markers for oral health in post-liver transplantation patients, as compared with systemically healthy dental outpatients (controls). In this case, 26 patients were enrolled in each group, with similar socio-demographic characteristics. Unstimulated whole saliva was collected; total protease activity and total protein content were measured. The oral health in both groups was assessed using a self-report oral health questionnaire. Data were analyzed using parametric and nonparametric tests. Comparable results were recorded in terms of salivary protein and protease activity assessments. In post-liver transplantation group, positive correlation was found between the salivary pH level and the salivary secretion rate (r = 0.39; p = 0.04). With respect to self-reported oral health, there were no significant differences between the two groups, except for dental and oral care habits, the controls reporting more frequently use of dental floss and mouthwash (p = 0.02, and p = 0.003, respectively). Considering the high risk for developing systemic complications after liver transplantation, oral health care is an important issue to be addressed, salivary investigations representing powerful tool for disease changes monitoring.

Effects of soybean and canola meals as dietary protein sources on the production performance and meat quality of shrimp

Vegetable dietary protein sources are cheaper alternatives to fishmeal in shrimp diets. This study assessed the impact of fermented and non-fermented soybean and canola meals on growth performance, in vivo and in vitro digestibility, digestive enzyme activities and meat quality of Litopenaeus vannamei. A total of 513 shrimps were randomly assigned to treatments (control and two experimental diets). Animals on the control diet (cd) were fed a commercial feed concentrate. For the other treatments, the fishmeal protein source was totally replaced by a mixture of soybean and canola meal (50:50), either unfermented (sc) or fermented (fsc). Results showed that fermentation significantly increased (P &lt; 0.05) the hydrolysis degree (hd) of sc meals by 12 % compared to that of their unfermented counterparts. Also, it was found that canola meal had higher hd compared to soybean meal, both before and after fermentation. The use of sc diet decreased protein digestibility in shrimps (P &lt; 0.05), although there was no significant variation in the activity of total proteases and chymotrypsin. Production performance traits of shrimps fed diets with fsc were comparable to those of shrimps on the control diet. The increase in shear force of shrimps fed fsc was accompanied by an increase in the water holding capacity (whc) by 8-9 % (P &lt; 0.05). Sensory attributes were similar across diets. In summary, this study showed it is possible to fully replace fish meal with fsc in shrimp diets without impairing production performance traits, dietary protein digestibility, and shrimp meat quality.

Dietary Use of the Microalga Chlorella fusca Improves Growth, Metabolism, and Digestive Functionality in Thick-Lipped Grey Mullet (Chelon labrosus, Risso 1827) Juveniles

In recent years, a clear emphasis has been placed on replacing fishmeal and fish oil in aquafeeds with other alternative ingredients, including algae, particularly in low trophic omnivorous fish species. This work aimed at evaluating the effects of moderate dietary supplementation with the green microalga Chlorella fusca on growth, metabolism, and digestive functionality in juvenile thick-lipped grey mullet (Chelon labrosus). Fish were fed a control diet (CT) or a diet containing 15% C. fusca (C-15) biomass during 90 days. C. labrosus fed with the C-15 diet showed higher growth performance (in terms of final weight and length, weight gain, and specific growth rate) than the control group. Somatic indices and muscle proximate composition were similar at the end of the feeding trial. Regarding fatty acids profile, C. fusca-fed fish showed a selective retention of docosahexaenoic acid (DHA) in the liver, and arachidonic acid (ARA), eicosapentaenoic acid (EPA), and DHA in the muscle. Dietary inclusion of this microalga significantly increased intestinal total alkaline protease, leucine aminopeptidase, and alkaline phosphatase activities in specimens fed with C-15 diet. Furthermore, intestine histological analysis revealed the absence of damage signs on gut morphology in fish fed the microalgae supplemented diet. Thick-lipped grey mullets fed the C-15 diet increased plasma glucose and decreased plasma lactate. Overall, the effects observed on liver (lipid metabolism, glycolysis and glycogenolysis) enzyme activities, together with adequate fatty acid profile, metabolic response, and gut morphology, and a significant increase in the intestinal mucosa’s digestive and absorptive capacity, could explain the positive effects on growth performance obtained in fish fed the microalgae-supplemented diet. In conclusion, the results obtained showed that C. fusca is suitable as dietary ingredient for feeding thick-lipped grey mullet juveniles.

Effects of dietary protein levels on growth performance, carcass composition, nutrient digestibility and digestive enzyme activity of the critically endangered peninsular carp,Hypselobarbus pulchellus(Day, 1870) fingerlings

The dietary protein requirement of the peninsular carp, Hypselobarbus pulchellus was investigated through a feeding trial conducted in aerated plastic tanks (50 L) with five isocaloric diets formulated to contain crude protein levels ranging from 20 to 40% (CP20, CP25, CP30, CP35 and CP40) using pure ingredients with casein and gelatin as the protein sources. Fingerlings (mean wt. 4.71 g) of H. pulchellus were fed at 5% of the biomass for a period of 60 days. The growth parameters increased with dietary protein level up to 35% followed by a decrease with CP40 diet. Lowest (p < 0.05) food conversion ratio was recorded with 35% protein diet. Protein efficiency ratio values were inversely proportional to the dietary protein level. The condition factor ranged from 0.94 to1.07 with no difference among the treatments. No difference (p > 0.05) was recorded in fish survival. Proximate composition analysis of fish carcass indicated no difference (p > 0.05) in moisture, fat and ash contents. Crude protein content on the other hand, showed values increasing with dietary protein level up to 35%, beyond which (CP40), it stagnated. Apparent digestibility coefficient for protein also increased gradually with the dietary protein level with a peak under CP35 and then decreased at CP40. Fat digestibility values, on the other hand, were similar (p > 0.05) for all diets. Analysis of the activity of digestive enzymes indicated highest activity of trypsin and total protease in both intestine and hepatopancreas of fish fed 35% crude protein diet. The second- order polynomial regression analysis for weight gain rate and specific growth rate indicated a dietary protein requirement between 31.80 and 32.76% for the fingerlings of H. pulchellus. This information on protein requirement would be useful in developing species specific feed for this critically endangered peninsular carp.

Lactiplantibacillus plantarum-Derived Biosurfactant Attenuates Quorum Sensing-Mediated Virulence and Biofilm Formation in Pseudomonas aeruginosa and Chromobacterium violaceum

Quorum sensing (QS) controls the expression of diverse biological traits in bacteria, including virulence factors. Any natural bioactive compound that disables the QS system is being considered as a potential strategy to prevent bacterial infection. Various biological activities of biosurfactants have been observed, including anti-QS effects. In the present study, we investigated the effectiveness of a biosurfactant derived from Lactiplantibacillus plantarum on QS-regulated virulence factors and biofilm formation in Pseudomonas aeruginosa and Chromobacterium violaceum. The structural analogues of the crude biosurfactant were identified using gas chromatography–mass spectrometry (GC–MS). Moreover, the inhibitory prospects of identified structural analogues were assessed with QS-associated CviR, LasA, and LasI ligands via in silico molecular docking analysis. An L. plantarum-derived biosurfactant showed a promising dose-dependent interference with the production of both violacein and acyl homoserine lactone (AHL) in C. violaceum. In P. aeruginosa, at a sub-MIC concentration (2.5 mg/mL), QS inhibitory activity was also demonstrated by reduction in pyocyanin (66.63%), total protease (60.95%), LasA (56.62%), and LasB elastase (51.33%) activity. The swarming motility and exopolysaccharide production were also significantly reduced in both C. violaceum (61.13%) and P. aeruginosa (53.11%). When compared with control, biofilm formation was also considerably reduced in C. violaceum (68.12%) and P. aeruginosa (59.80%). A GC–MS analysis confirmed that the crude biosurfactant derived from L. plantarum was a glycolipid type. Among all, n-hexadecanoic acid, oleic acid, and 1H-indene,1-hexadecyl-2,3-dihydro had a high affinity for CviR, LasI, and LasA, respectively. Thus, our findings suggest that the crude biosurfactant of L. plantarum can be used as a new anti-QS/antibiofilm agent against biofilm-associated pathogenesis, which warrants further investigation to uncover its therapeutic efficacy.

Influence of wheat and rice bran fermentation on water quality, growth performance, and health status of Common carp (Cyprinus carpio L.) juveniles in a biofloc-based system

The present study was aimed to compare the effect of wheat and rice bran fermented with probiotics (Bacillus coagulants, Bacillus subtilis) on liver and intestine histology of Common carp. Additionally, its effect on water quality, growth performance, hemato-serological indices and oxidative stress in biofloc based system for Common carp juveniles was investigated. To compare fermented (FWB + BFT: fermented wheat bran, FRB+BFT: fermented rice bran) and non-fermented (WB + BFT: wheat bran, RB + BFT: rice bran) treatments, 375 healthy juveniles (25.1 ± 1.6 g) were randomly distributed in 12 tanks (70 L). In the fermented treatments, wheat and rice bran were pre-fermented for 24 h, and then added to the culture tanks and in control. No carbon source was added while 30% of the water was changed on a daily basis. After 60 days, the results revealed that total ammonia nitrogen, pH, biofloc floc volume, and dissolved oxygen decreased in the fermented sources compared with those of the non-fermented treatments. Moreover, the results indicated that fermentation improved growth performances, and the highest significant weight gain and protein efficiency ratio, along with the lowest feed conversion ratio and feed intake belonged to FWB + BFT, which was different with non-fermented brans (P < 0.05). The fish reared in FWB + BFT had a significantly higher total protease, amylase, and lipase activity than those in the non-fermented groups (P < 0.05). A significantly higher body protein was seen in the fermented treatments (P < 0.05), while due to high lipid content in rice bran, the highest body lipid content was observed in the rice bran treatments. In comparison with non-fermented treatments, the most sero-immunological parameters improved in FWB + BFT group and significant difference was seen (P < 0.05). The experimental treatments affected the antioxidant enzymes, and the highest superoxide dismutase and glutathione peroxidase as well as the lowest malondialdehyde were observed in the fermented groups, which was different with the non-fermented treatments (P < 0.05). Histological changes were found in the juveniles intestine, and mucosal layer quantification and qualification than the fermented groups significantly improved in comparison with those in non-fermented treatments (P < 0.05). Overall, the result of this experiment revealed that fermentation of complex carbon resources improves water quality and increases growth performance and health status in the biofloc system.

Effect of Lemna minor supplemented diets on growth, digestive physiology and expression of fatty acids biosynthesis genes of Cyprinus carpio

The potential nutritional value of duckweed Lemna minor (Lemnaceae) was evaluated for common carp Cyprinus carpio fry. Fish were fed diets containing five graded levels of duckweed: 0% (LM0, control), 5% (LM5), 10% (LM10), 15% (LM15) and 20% (LM20). The final weight and specific growth rate were significantly higher in LM15 and LM20 diets fed fish compared to others. Feed conversion ratio was minimum in fish fed diet LM20. Amylase activity was significantly higher in LM0 treatment. Total protease, trypsin and chymotrypsin activities showed linear relationships with the increased level of duckweed in the diet. Protein and essential amino acids contents were significantly higher in carp fed diets LM15 and LM20 compared to others. Lipid content was significantly higher in fish fed duckweed-based diets compared to control. A direct relationship was found between the inclusion level of duckweed in the diet and n-3 long-chain polyunsaturated fatty acid (LC-PUFA) content of carp. Contents of desaturated and elongated products of dietary linolenic acid (18:3n-3) including 20:4n-3, 20:5n-3, 22:5n-3 and 22:6n-3 increased in a graded manner with increasing dietary duckweed. The monounsaturated fatty acids and n-6 PUFA contents reduced significantly in fish fed duckweed. Expression of fads2d6, elovl2, elovl5 and fas were higher in carp fed diets LM10, LM15 and LM20 compared to control fish. The inclusion of L. minor in diet enhanced the nutritional value of carp by increasing protein, lipid, amino acids and n-3 PUFA contents.