Acid Protease Activity Research Articles

The changes in Alkaline, Neutral and Acid Protease Activities of Artemia Enriched with Commercial Emulsion and Different Additive Combinations

The biochemical compositions and the changes observed in alkaline, neutral and acid protease activities of Artemia enriched with commercial emulsion and different additive combinations were determined. Artemia nauplii (ArtN), GroBiotic-A (GA), Red Algamac (RA), Red Algamac:GroBiotic-A (50:50) (RA:GA (50:50)), Spirulina (SP), Spirulina:Red Algamac (50:50) (SP:RA (50:50)), Spirulina:GroBiotic-A (50:50) (SP:GA (50:50)) and Spirulina:Red Algamac:GroBiotic-A (33:33:33) (SP:RA:GA (33:33:33)) were tested in the study. The lowest and highest protein contents after the enrichment of Artemia were 40.74±1.02% (RA) and 55.03±1.26% (SP:RA:GA (33:33:33)), respectively. The lowest lipid contents of tested groups were found in 5.63±0.47% (GA) and 5.63±0.84% (RA:GA (50:50)). The highest lipid value after the enrichment were observed in 16.98±1.15 % (RA). The lowest and highest ash values observed after the enrichment were 4.51±0.27% (SP:GA (50:50)) and 6.07±0.35% (RA) (p<0.05). The lowest and highest protease activities of the pH=3, pH=4, pH=5, pH=6, pH=7 and pH=8.5 values were 18.18±0.37 U/mg protein (GA), 31.04±0.38 U/mg protein (RA), 9.1±0.32 U/ mg protein (SP), 9.66±0.19 U/mg protein (SP), 16.94±0.61 U/mg protein (SP), 63.09±0.75 U/mg protein (SP) and 33.77±0.59 U/mg protein (RA:GA (50:50)), 57,54±0.34 U/mg protein (RA:GA (50:50)), 23.75±0.28 U/mg protein (GA), 40.82±0.49 U/mg protein (GA), 69.94±0.65 U/mg protein (GA), and 286.14±8.2 U/mg protein (GA) (p<0.05). In conclusion, GA and SP:RA:GA (33:33:33) enrichment combinations are recommended as an alternative to enrichment products. On the other hand, SP and RA should not be used alone due to the disadvantages such as the biochemical composition and proteolytic enzyme activities of Artemia observed in the present study. 

Effects of wheat‐legume cultures on the fermentation quality and protein degradation of silage

AbstractAmong the cereal crops, whole‐crop wheat (Triticum aestivum L.) has become a common silage material in many countries of the world. However, there was little information about its planting methods. In order to obtain a optimum planting and utilization methods, this research investigated the effects of wheat‐legume cultures on the fermentation quality and protein degradation of silage. In the present research, wheat, alfalfa (Medicago sativa L.), common vetch (Vicia sativa L.), milk vetch (Astragalus sinicus L.) and smooth vetch (Vicia villosa L.) were planted by monoculture and mixture of wheat with other one, and they were ensiled. There were no significant differences in pH value, lactic acid, acetic acid and butyric acid contents among all silages with wheat, either monoculture or mixture with legume (p > .05). The wheat‐legume silages had higher lactic acid and lower butyric acid contents than their corresponding legume silages (p < .05). The non‐protein nitrogen and peptide‐N contents of wheat silage were significantly lower than those of wheat‐legume silages (p < .05). Aminopeptidase and acid proteinase activities of monoculture legume and wheat‐legume silages were significantly higher than those of wheat silage (p < .05). Overall, the chemical composition of forage has a greater influence on the fermentation quality and protease activity of silage compared to epiphytic microbes. The wheat‐legume cultures could effectively improve the fermentation quality of silage compared to monoculture legumes and wheat.

Development of a novel multi-strain wheat Qu with high enzyme activities for Huangjiu fermentation.

Wheat Qu has long been used as a fermentation starter to produce Huangjiu. Wheat Qu quality depends on its microbial community structure and the hydrolytic enzymes generated by the micro-organisms. Strain YF1 and YF2 were successfully screened as they exhibited high acidic protease (231.9 ± 1.4U g-1 ) and cellulase (7.1 ± 0.6U g-1 ) activities. Based on a morphological and sequence analysis of the internal transcribed spacer (ITS) gene, YF1 and YF2 were identified as Rhizopus oryzae and Aspergillus niger, respectively. Cooked wheat Qu was produced using mixed fungal starter fermentations with Aspergillus oryzae SU-16, YF1, and YF2. For Qu-making, the optimized conditions for fermentation time, water content, and inoculum size were 47.8h, 69.4%, and 6.1%, respectively. Under these conditions, compared with single-strain cooked wheat Qu, enzyme activities of amylase, acidic protease, and cellulase increased by 27.4%, 657.1%, and 1276.2%, respectively. Short peptides and free amino acids contents increased by 19.6% and 131.8%, respectively. This wheat Qu was used for Huangjiu brewing, and the alcohol content increased by approximately 14.6% because of the increased starch hydrolysis efficiency mainly attributed to its high enzyme activity. Using mixed fungal strains as starter cultures may be an efficient strategy to improve wheat Qu quality, with great potential for application in industrial Huangjiu production. © 2021 Society of Chemical Industry.

Changes of Physiochemical and Enzymatic Activities of doenjang Prepared with Different Amount of Rice koji during 30 Days of Fermentation

Koji is an intermediate fermentation agent, made by inoculating known microorganisms in grains, such as rice, beans, and barley, to hydrolyze starch or protein. The quality of koji can influence the final quality of doenjang. This study aimed to investigate changes in the physiochemical and enzymatic activities of doenjang prepared with different amounts of rice koji during a 30-day fermentation period. Three doenjang samples were prepared with varying levels of rice koji: K1 (11% reduced), K2 (control), K3 (11% increased). Physiochemical characteristics including pH, TA, acid value, moisture content, color, sugar and reducing sugar content, and enzymatic activities including α- and β-Amylase, acidic and neutral protease activities. Samples were taken every 5 days for 30 days of fermentation period. The doenjang with a high content of rice koji had higher levels of total sugars, reducing sugars, alcohol, and protein enzyme activity than the doenjang samples with a lower content of rice koji (p < 0.05). However, no differences in the physiochemical and enzymatic activities were found between the doenjang made with a lower amount of koji and the control doenjang during fermentation (p > 0.05).

Characterization of digestive enzymes during early ontogeny of white Snook (Centropomus viridis).

The white snook (Centropomus viridis) is a species with great aquaculture potential, therefore, the present study aims two objectives; 1) to characterize digestive enzymatic activity during larval development and; 2) characterize the diversity and functionality of digestive enzymes in an early juvenile stage of C. viridis. On first feeding, larvae were 2.75 ± 0.09 mm total length and grew to 24.35 ± 4.35 mm after 42 days. The specific activity of acid proteases was detected with low activity from day 1 (Days after hatching, DAH) to day 21, and increased at 23 DAH, reaching maximum activity at 40 DAH. Meanwhile, digestive enzymatic activity of alkaline proteases was observed from hatching to day 40. From hatching until 40 DAH, the presence of alkaline proteases, trypsin, chymotrypsin, leucine aminopeptidase, α-amylase and lipase were detected with different activity patterns. Total and specific activity of digestive enzymes on juveniles showed higher activity of acid than alkaline proteases, while α-amylase had a higher activity than lipases. The maximum activity of acid proteases was observed at 40 °C and at pH 2.0, while digestive alkaline proteases showed maximum activity at 60 °C. α-amylases and lipases showed their maximum activities at 50 °C. The maximum alkaline protease and α-amylase activities were found at pH 7 to 9. The enzymatic activity of juvenile's acid proteases was highly inhibited by Pepstatin A (96%), however the activity of alkaline proteases incubated with PHEN, TLCK, SBTI, PMFS, and OVO showed reductions of 51.29, 30.16, 27.98, 27.26, and 24.68% respectively. Lipase activity was totally inhibited with Ebelactone B, and highly inhibited by Ebelactone A, Orlistat, 1% SDS, and PMFS (96.12, 77.16, 64.22, and 51.29%, respectively). Seven bands (102.6, 65.7, 58.9, 40.6, 27.4, 21.5, and 15.8 kDa) resolved by protein electrophoresis were detected with alkaline protease activity, identified as serine proteases and metalloproteases, and three bands (57, 43.9, and 32.6 kDa) with lipase-like activity were also identified. These results show that C. viridis ontogeny entails an indirect development of its digestive system with a functional stomach on day 23, and characterized by increases in pepsin activity. Indeed, white snook ontogeny shows a similar developmental trajectory to other carnivorous marine fish, showing a diversity of alkaline proteases that work in a wide range of pH and temperatures. Thus, the identification of these enzymes provides advantages to formulate white snook aqua-feeds.

Length ratio, histological structure, feed composition, and enzyme activity in the gut of yellow rasbora (Rasbora lateristriata Blkr.)

A study of the ratio of gut length, histological structure, feed composition, and enzyme activity in the foregut had carried out to determine the feed category of yellow rasbora. The study used a survey method with sampling in the Banjaran River, Banyumas, Central Java. The research data had analyzed quantitatively and descriptively. The results showed that the gut length ratio of yellow rasbora ranged from 0.53 to 0.81. Gut histological showed no stomach structure with the relative height of the villi in the middle intestine approaching 0.5. Feed composition in the foregut showed that 60% was animal, and the rest were detritus and microalgae. Measurement of protease activity at foregut showed that no acidic protease activity but found alkaline proteases. In conclusion, yellow rasbora was an omnivorous fish with a short intestine and no functioning stomach.

Influence of the Treatment Used in Inflammatory Bowel Disease on the Protease Activities.

IntroductionThere is growing evidence that intestinal proteases have a role in the pathogenesis of gastrointestinal inflammatory diseases. Inflammatory bowel disease (IBD), which includes Crohn’s disease (CD) and ulcerative colitis (UC), has an additional source of proteases represented by infiltrated and activated inflammatory cells. The aim of our study was to determine proteolytic system activity in patients with CD and UC. We limited the number of proteases tested by determining proteases active in acidic, neutral and alkaline pH.Materials and MethodsThe study included 40 patients with IBD – 20 CD patients and 20 UC patients. The control group consisted of 20 healthy subjects. Among the 20 CD patients, 17 were treated with aminosalicylates, 14 with azathioprine, and 4 with corticosteroids, while 8 patients were undergoing biological treatment. Among the 20 UC patients, 19 were treated with aminosalicylates, 8 with azathioprine, and 3 with corticosteroids. The total protein concentration was assayed by the Lowry method. The optimal pH was assayed in pH from 2.2 to 12.8, separated by 0.2 intervals. Proteolytic activities were determined against different substrates (gelatine, haemoglobin, ovalbumin, albumin, cytochrome C, and casein), and haemoglobin was the optimal substrate. Protease activities were determined according to Anson method. Determination of the activities of natural inhibitors of acidic, neutral and alkaline proteases is based on the Lee and Lin method.ResultsDecreases were observed in the activities of acid proteases (pH 5), alkaline proteases (pH 7), and neutral proteases (pH 7.6 and 8.6) in the groups of CD patients in remission in comparison with the active phase. In the group of patients with biologically treated CD patients, acid protease activity (pH 5.0) was lower than in CD patients not receiving biological treatment. Activities of neutral (pH 7.0) and alkaline (pH 7.6 and 8.6) proteases in the plasma of patients with UC in remission were lower in comparison to the active phase. Activities of acid (pH 5.0) and alkaline (8.6) protease inhibitors were higher in CD patients in the active phase in comparison to remission. In UC patients with exacerbation of the disease, the activity of alkaline (pH 8.6) protease inhibitors was increased compared to remission.Conclusion1. Our research may suggest that the immunomodulatory treatment used in IBD, aimed at reducing the level of leukocytes and reduction of inflammation, may contribute to a reduction in protease activity. 2. The decrease of protease activities in patients with CD and UC in remission may be a marker suggesting the patients’ response to the treatment.

ROOT ASSOCIATED BACTERIAL ENDOPHYTES FROM POACEAE PLANTS: IDENTIFICATION, CHARACTERIZATION AND PLANT GROWTH PROMOTION

Diazotrophic endophytic bacteria contribute to the plant growth using various plant growth promoting traits as well as by inducing the plant defence mechanism upon pathogen attack. Aim of the present study was to isolate true diazotrophic endophytic bacteria from the total diazotrophic bacterial community of wheat and pearl-millet plants. Further, these isolates were evaluated for their potential of plant growth promotion by in vitro and in vivo experiments. We isolated total three diazotrophic endophytic bacteria based on their growth after repetitive subculturing on nitrogen free medium. Molecular characterization of all three isolates showed affiliation to the genera Agrobacterium, Pseudomonas and Brevundimonas. In vitro analysis of plant growth promoting traits showed positive result for indole acetic acid (IAA) production, cellulase and protease activity. The IAA production is found between the ranges of 98 to 113 µg ml-1. All the endophytic bacterial isolates showed the PCR amplification of NifH gene and ammonia production. Diazotrophic endophytic bacterial isolates (PR1, JB3 and JB6) were tested for their capacity to promote the plant growth using pot experiment. All the diazotrophic endophytic bacteria differ in their plant growth promotion ability as analyzed by various plant growth parameter compared to the untreated control plants. In Pot experiment, PR1 and JB6 showed a significant difference in dry weight of root, whereas JB3 and JB6 showed the significant differences in shoot length and total nitrogen content (p≤0.05) compared to the untreated plants.

Bafilomycin A1 enhances NLRP3 inflammasome activation in human monocytes independent of lysosomal acidification.

The release of interleukin (IL)-1β from primary human monocytes in response to extracellular LPS occurs through the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome. In primary monocytes, in response to LPS, NLRP3 inflammasome activation is characterized by an independence of K+ efflux and ASC speck formation and has been termed the 'alternative' pathway. Here, we report that pharmacological inhibition of V-ATPase with bafilomycin A1 exacerbated LPS-induced NLRP3 inflammasome activation in primary human monocytes. Inhibition of V-ATPase in the presence of extracellular LPS led to NLRP3-dependent, K+ efflux-independent, ASC oligomerization and caspase-1 activation. Although V-ATPases are required for lysosomal acidification, we found that acidic lysosomal pH and protease activity were dispensable for this altered response, suggesting that V-ATPase inhibition triggered alternative signalling events. Therefore, V-ATPases may serve additional roles during NLRP3 inflammasome activation in primary human monocytes.

Effects of low-temperature treatment on the activity of proteolytic enzymes in various flour types

This work was aimed at investigating effects of low-temperature processing on the activity of proteolytic enzymes in various flour types. This study allowed an improved understanding of the mechanisms that change biotechnological processes in semi-finished dough products during low-temperature storage. The study of the effect of long-term low-temperature exposure on the activity of proteolytic enzymes in various flour types showed that this parameter depends on the medium pH, as well as on the flour type. During low-temperature storage, the activity of acid proteases tend to decrease by, on average, 10% in both traditional and non-traditional types of flour used for baking. The activity of weakly acidic and weakly alkaline proteases under the influence of low temperatures during storage depends on the flour type. At pH = 5.5, an increase in the duration of low-temperature exposure leads to a decrease in the proteolytic activity of spelt, wheat and buckwheat flour by, on average, 20, 12.5, and 18%, respectively. Conversely, this parameter increases in rye and oat flour by 12 and 28%, respectively. Under the influence of freezing and during low-temperature storage, the activity of weakly alkaline proteases in all studied flour types increases by 15.9%, except for buckwheat, the proteolytic activity of which decreases by 1.5–2 times during storage. It was established that proteolytic enzymes of corn flour exhibit the greatest resistance to long-term storage in a frozen form. Knowledge of the effect of low-temperature processing on the activity of proteolytic enzymes is important for predicting the rheological properties of semi-finished dough products and structural-mechanical and organoleptic characteristics of finished products. In addition, this knowledge facilitates the development of recipes and technological parameters for producing new bakery products based on frozen semi-finished products from traditional and non-traditional flour types.

Galleria mellonellalarvae fat body disruption (Lepidoptera: Pyralidae) caused by the venom ofHabrobracon brevicornis(Hymenoptera: Braconidae)

The ability of Habrobracon brevicornis venom to elevate the nutritional suitability of a host by affecting the host larvae fat body condition was studied. To understand whether H. brevicornis crude venom impacts the host biochemical profile, the concentrations of total lipids and main sugars in the host larvae lymph were analyzed. All measurements were carried out during the first 3 days after envenomation. A significant increase in the lipid level was fixed only on the second day after envenomation. A significant increase in the total trehalose count was detected during all 3 days, while a significant increase in glucose concentration was noted only on the first day. Well-observed disruptions were fixed in thin and semithin sections of the G. mellonella larval fat body starting from the second day after envenomation. Significant increases in both phospholipase A2 and C enzyme activity as well as acid proteases were detected in the wax moth fat body after envenomation during all experimental times. At the same time, imbalances in the antioxidant system, including changes in the activities of superoxide dismutase, peroxidases, catalase, and glutathione-S-transferase, were detected. The reliable increase in the expression of the gene encoding Hsp70 was fixed both for 24 and 48 h after envenomation, while a reliable increase in the expression of the gene encoding inhibitor of apoptosis protein was detected only 24 h after wax moth larvae envenomation. Considering the absence of DNA fragmentation, the imbalance in the "ROS/antioxidants" system, and the increased activity of phospholipases and acid proteases in the fat body cells from envenomated wax moth larvae, we can hypothesize that the fat body disruption occurs in a necrotic manner. The results of the work expand the knowledge about the biochemical aspects of interaction between ectoparasitoids and their hosts.

Effects of the degree of milling on the quality characteristics of rice ‘Nuruk’

This study aimed to investigate the effects of the degrees of milling of rice (0-50%) on the physicochemical properties and enzymatic activities of rice ‘Nuruk’. As results, the contents of the general components of milled rice, except for the starch value (85.13-90.99%) decreased as the degree of milling increased. The moisture content of rice with different degrees of milling ranged from 11.04 to 12.68% and significantly decreased as the degree of milling increased. Furthermore, the hydration rate increased as the degree of milling increased. The pH of rice ‘Nuruk’ was the lowest at 5.32 in the 0% milled rice ‘Nuruk’ and highest at 5.98 in the 30% milled one, which indicated no correlation between pH and degree of milling. By contrast, the soluble solid and reducing sugar contents which are correlated with the starch value of rice increased as the degree of milling increased. For the enzymatic activities of each rice ‘Nuruk’, there was no clear trend for the α-amylase and acidic protease activities with respect to the degree of milling, whereas the glucoamylase activity decreased with increasing degree of milling. Correlation analyses indicated that the activity of glucoamylase decreased as the starch value of rice increased, but increased as the crude protein content of rice increased. The activity of acidic protease had a negative correlation with the crude lipid content of rice.

Enhancement of Acid Protease Activity of Aspergillus oryzae Using Atmospheric and Room Temperature Plasma

Atmospheric and room temperature plasma (ARTP) system is a novel and efficient mutagenesis protocol for microbial breeding. In this study, ARTP was employed to treat spores of Aspergillus oryzae strain 3.042 for selection of high acid protease producers. With an irradiation time of 150 s at the lethal rate of 90%, 19 mutants with higher acid protease activity were initially selected based on different mutant colony morphology and ratio of the clarification halo of protease activity to the colony diameter. Measurements of the acid protease activity revealed that mutant strain B-2 is characterized by a steady hereditary stability with increased acid protease, neutral protease and total protease activities of 54.7, 17.3, and 8.5%, respectively, and decreased alkaline protease activity of 8.1%. In summary, the identified mutant strain B-2 exhibits great potential for the enhancement of the insufficient acid protease activity during the middle and later stages of soy sauce fermentation.

Effects of ultraviolet photooxidation of cypermethrin on the activities of phosphatases and digestive enzymes, and intestinal histopathology in African catfish, Clarias gariepinus (Burchell, 1822).

The possibility of ultraviolet (UV) photooxidation of cypermethrin generating more toxic intermediates or isomers demands that studies that look at the effects of cypermethrin and UV irradiation under a coexposure scenario be carried out. In this study, juvenile African catfish (Clarias gariepinus) were exposed to 50 µg/L cypermethrin, 100 µg/L cypermethrin, UV, 50 µg/L cypermethrin + UV or 100 µg/L cypermethrin + UV, in a static renewal for 3 weeks. The control fish were maintained in uncontaminated water, and not exposed to UV radiation. After the exposure duration, the fish were killed, and the activities of acid phosphatase, alkaline phosphatase, amylase, protease, and lipase were determined in the liver or intestinal homogenates. Also, the histopathology of some sections of the intestine was performed. The results showed that the activities of the enzymes decreased significantly following exposure to cypermethrin while there was no change in the activities of the enzymes due to UV irradiation alone. The histopathological analyses indicated that exposure to cypermethrin caused alterations in the histoarchitecture of the fish such as severe erosion of the mucosa layer, faded lamina propria, and disintegration of the muscle layer. The exposure of fish to both cypermethrin and UV irradiation caused significant decrease in the activities of the enzymes. This could be an indication that UV irradiation has the tendency to potentiate cypermethrin-induced toxicity in fish.

Effects of Saccharomycopsis fibuligera and Saccharomyces cerevisiae inoculation on small fermentation starters in Sichuan-style Xiaoqu liquor

Xiaoqu liquor is a type of distilled spirit in China prepared on a small scale from a small solid starter culture. Although this liquor is popular in southwestern China, it can have a dull taste, limiting its market. To improve the flavour profile of Xiaoqu liquor, we selected two functional yeast strains (Saccharomycopsis fibuligera and Saccharomyces cerevisiae) from Zaopei (fermented grain) of Baijiu liquor and used them for Xiaoqu liquor fermentation. Compared with traditional Xiaoqu (Starter), bioaugmentation inoculation increased the glucoamylase and acidic protease activities and the ethanol synthesis rate, while decreasing the acidity of the Zaopei (fermented grains) in the early stage of fermentation. By the end of the fermentation process, the alcohol and ester content had also increased by 42.5% and 11.8%, respective, and that of aldehydes and ketones, and heterocyclic compounds decreased by 73.7% and 77.1%, respectively. Traditional isolation and high-throughput sequencing were employed to analyse the microorganisms in the Zaopei. Bioaugmentation inoculation increased the microbial diversity of Xiaoqu liquor during the fermentation process. The dominant fungus during fermentation using the two types of starter cultures was S. cerevisiae, whereas the dominant bacteria was Pseudomonas, followed by Bacillus, Weissella, Lactobacillus, and Bacteroides. Principal component analysis of the bacterial community structure and flavour substances in the Zaopei produced using the two strains revealed that there were few differences between the two liquors and that inoculation with functional yeasts may not change the flavour substances in Xiaoqu liquor. However, correlation analysis showed that Escherichia Shigella, Terrisporobacter, Bacillus, Clostridium, and Prevotellaceae are the main microorganisms in the Xiaoqu liquor fermentation process. These results lay the foundation to improve the quality of Xiaoqu liquor.

Effects of dietary protein levels on activities of protease and expression of ingestion and protein digestion‐related genes in Nile tilapia juveniles

While some studies have investigated the effects of dietary protein on the activities of protease in Nile tilapia, little information exists about these enzymes and hormones regulating appetite at the molecular level. Therefore, we investigated the performance, protease activities and expression of genes related to protein intake and digestion in juvenile tilapia fed with diets containing different levels of crude protein (CP): 25.14, 31.12, 36.60 and 42.05%. The fish were fed to apparent satiation three times a day for 65 days. The animal performance and the retention rates of protein and energy linearly decreased with an increase in dietary CP content. A positive quadratic effect of CP on pepsinogen was observed, although the acid protease activity was not affected. Trypsinogen and trypsin activity in the intestine presented similar patterns, showing a positive quadratic response to dietary protein levels. A linear increase in intestinal chymotrypsinogen expression was observed, but the activity of chymotrypsin showed a positive quadratic response. In addition, the expression of cholecystokinin (cck) and peptide yy (pyy) increased linearly with increasing CP. Dietary protein modulates the activity of alkaline proteases as well as the expression of these protease genes and hormones involved in appetite regulation. These changes can help expand our understanding of feed intake and digestion control, thereby improving feed formulations for this species.

Feasibility of multi-hydrolytic enzymes production from optimized grape pomace residues and wheat bran mixture using Aspergillus niger in an integrated citric acid-enzymes production process

In this study, the potential of the co-generation of hydrolytic enzymes in the biorefinery plant for citric acid fermentation was investigated. Aspergillus niger B60 mycelium along with the solid residue after the recovery of sugars from white pomace (WP′) were recycled from citric acid fermentation. A mixture design was used to determine the optimum ternary feedstock mixture composed of WP′ (15%), red grape pomace (15%) and wheat bran (70%) that produced the target enzymes with high activities, which were compared to those from pure feedstocks. Maximum carboxymethyl cellulase, polygalacturonase, amylase, xylanase and acid protease activities obtained through solid-state fermentation (120 h, 30 °C) of the feedstock mixture were 668 IU/g, 3,151 IU/g, 1,099 IU/g, 579 IU/g and 204 IU/g (dry mass basis), respectively. The system was successfully simulated in SuperPro Designer. Results showed that the enzymes production process serves as the main contributor to the profitability of the biorefinery plant.

Effects of Sepiolite and Biochar on Enzyme Activity of Soil Contaminated by Cd and Atrazine.

The effects of sepiolite and biochar on the enzymatic activities of the soil in Cd- and atrazine-contaminated soils were studied. During the growth of pakchoi, the activities of acid phosphatase, sucrase, acid protease, and cellulase decreased, catalase activity increased, and urease activity decreased first and then increased. At the first harvest, compared with that for the control group, the soil pH after treatment with remediation materials increased from 5.41 to 7.43; the activities of urease, acid protease, and catalase increased by 62.8%, 38.6%, and 86.1%, respectively. And the activities of sucrase and acid phosphatase decreased by 17.3% and 24.7%, respectively. At the second harvest, the activities of acid phosphatase, acid protease, and cellulase continued to increase, but those of sucrase and catalase decreased. The results showed that soil enzyme activity was closely related to the type and addition of remediation materials, as well as the type of the enzyme.

The onset of piscivory in a freshwater fish species: analysis of behavioural and physiological traits.

The onset of piscivory in fish, resulting in a shift from zooplankton or invertebrate to fish prey, was studied on pikeperch (Sander lucioperca) larvae displaying and not displaying piscivorous behaviour at different ages (23, 30, 37, 44 and 52 days post-hatching) using behavioural (attack, capture and swimming activity), morphological (allometry) and digestive enzymatic (trypsin, α-amylase and pepsin) analyses. The shift from zooplanktonic food items (Artemia nauplii) to a piscivorous diet did not occur at the same time for all individuals within the same cohort. Predation tests, conducted under controlled conditions (20°C; ad libitum feeding), showed that some larvae attacked fish prey as early as the age of 3 weeks [11.0 ± 1.3 mm total length (TL)], whereas others did not start until the age of 6 weeks (16.6 ± 1.9 mm TL). Piscivorous individuals were bigger, with larger heads, longer tails, higher acid protease and lower alkaline protease activities, than non-piscivorous conspecifics. In conclusion, high interindividual variability in morphological and digestive system developments linked to the development of predatory abilities could induce cannibalism in fish.

Effect of different proportions of crab and squid in semi-moist diets for Octopus maya juveniles

During the present study, the effect of five semi-humid experimental diets with different proportions of crab and squid were tested, on juveniles of the red octopus, Octopus maya. For this, five prepared diets based on crab and squid (SC50, SC60, SC70, SC80, and SC90; the number indicates the percentage of squid in each diet), were fed to juvenile O. maya during 60 days. Feeding and growth rates, survival, glycogen content in muscle, soluble protein and digestive enzymes activity in digestive gland (DG), fatty acids and amino acid composition of diets and octopus juvenile were determined. Higher growth, survival and nutritional condition was obtained with diets SC50, SC60 and SC70 compared to SC80 and SC90 (P<0.05). A direct relation between glycogen concentration in the muscle and the digestive gland (DG), as well as soluble protein in the DG were also obtained for octopuses fed these three diets. Higher alkaline and acid protease activity were found on octopuses fed SC60 and SC90, respectively (P<0.05). Results suggest that a proportion of 70% squid and 30% crab may be considered adequate to satisfy nutritional requirements for the fattening of O. maya juveniles. Nevertheless, a proportion of 30% of crab in the diet, is still high, regarding production costs and profitability, and further research will focus on the total replacement of crab by less expensive raw material with similar nutritional value, to increase economic viability of commercial O. maya culture.