Acid Protease Activity Research Articles

Some low homogenization pressures improve certain probiotic characteristics of yogurt culture bacteria and Lactobacillus acidophilus LA-K

Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus salivarius ssp. thermophilus, and Lactobacillus acidophilus are dairy cultures widely used in the manufacture of cultured dairy products. Commonly used homogenization pressures in the dairy industry are 13.80 MPa or less. It is not known whether low homogenization pressures can stimulate bacteria to improve their probiotic characteristics. Objectives were to determine the effect of homogenization at 0, 3.45, 6.90, 10.34, and 13.80 MPa on acid tolerance, bile tolerance, protease activity, and growth of L. delbrueckii ssp. bulgaricus LB-12, S. salivarius ssp. thermophilus ST-M5, and L. acidophilus LA-K. The cultures were individually inoculated in cool autoclaved skim milk (4°C) and homogenized for 5 continuous passes. Growth and bile tolerance of samples were determined hourly for 10h of incubation. Acid tolerance was determined every 20min for 120min of incubation. Protease activity was determined at 0, 12, and 24h of incubation. All homogenization pressures studied improved acid tolerance of L. delbrueckii ssp. bulgaricus LB-12 but had no beneficial effect on protease activity and had negative effects on growth and bile tolerance. A pressure of 6.90 MPa improved acid tolerance, bile tolerance, and protease activity of S. salivarius ssp. thermophilus ST-M5, but none of the homogenization pressures studied had an effect on its growth. Homogenization pressures of 13.80 and 6.90 MPa improved acid tolerance and bile tolerance, respectively, of L. acidophilus LA-K but had no effect on protease activity and its growth. Some low homogenization pressures positively influenced some characteristics of yogurt culture bacteria and L. acidophilus LA-K. Culture pretreatment with some low homogenization pressures can be recommended for improvement of certain probiotic characteristics.

Temperature and dietary starch level affected protein but not starch digestibility in gilthead sea bream juveniles

A study was carried out with gilthead sea bream juveniles to assess the effect of water temperature (18 and 25°C) and dietary pregelatinized starch level (10, 20 and 30%) on digestibility of protein and starch and on the activity of proteolytic and amylolytic enzymes. ADC of pregelatinized starch was very high (>99%) irrespectively of dietary inclusion level, and it was not affected by water temperature. ADC of protein was also high (>90%) but improved at the higher water temperature. Dietary starch interacted with protein digestibility, which decreased as dietary starch level increased. Temperature affected both acid and basic protease activities, with acid protease activity being higher at 25°C and basic protease activity being higher at 18°C. However, total proteolytic activity and amylase activities were not affected by water temperature. Dietary carbohydrate exerted no effect on proteolytic or amylolitic activities. It is concluded that gilthead sea bream juveniles digest pregelatinized starch very efficiently irrespective of water temperature, due to adjustments of amylase activity to cope with temperature differences. Pregelatinized starch interacts negatively with protein digestibility, with the ADC of protein decreasing as dietary starch levels increase.

Aspergillus속과 Bacillus subtilis를 이용한 된장메주 발효 중 품질 특성

메주의 산업화를 위해, 종균으로서는 A. oryze와 A. sojae 그리고 B. subtilis를 병용하고, 습도조절과 함께 <TEX>$28^{\circ}C$</TEX>에서 12일간 발효하면서 메주의 품질특성 변화를 조사하였다. 그리고 이들 종균 접종 메주와 순창 고추장 민속마을에서 입수한 된장용 전통메주의 효소 활성도를 비교하였다. 즉, A. oryzae를 접종한 메주(=AO메주), A. oryze와 B. subtilis를 접종한 메주(AOBS메주), A. sojae를 접종한 메주(=AS메주), A. sojae와 B. subtilis를 접종한 메주(=ASBS메주)를 12일 동안 발효시키면서 메주별로 품질 변화를 관찰하였다. 세균수와 곰팡이수는 각각 발효초기 6.48~6.69 log cfu/g, 5.00~5.71 log cfu/g에서 발효 2일에 8 log cfu/g 이상, 6 log cfu/g 이상으로 증가한 후 발효 12일 까지 세균수는 유지되었고, 곰팡이수는 감소 경향을 보였다. 아미노태 질소 함량은 발효 2일에 430.5~577.5 mg% 범위를 나타내었다. 중성 protease 활성도는 전통메주 <TEX>$1,258.0{\pm}38.8$</TEX>, AS메주 <TEX>$1,238.3{\pm}38.6$</TEX>, AO메주 <TEX>$1,204.1{\pm}24.1$</TEX>, ASBS메주 <TEX>$1,040.6{\pm}10.6$</TEX>, AOBS메주 <TEX>$1,033.5{\pm}11.2$</TEX> unit/g순으로 나타났다. 산성 protease활성도는 AO메주 <TEX>$1,030.1{\pm}19.1$</TEX>, 전통메주 <TEX>$1007.7{\pm}30.5$</TEX>, AS메주 <TEX>$990.9{\pm}25.0$</TEX>, AOBS메주 <TEX>$910.9{\pm}15.3$</TEX>, ASBS메주 <TEX>$888.2{\pm}15.7$</TEX> unit/g 순이었다. To industrialize meju, four kinds of meju (Korean-style soybean koji) were made with humidity-controlled fermentation for 12 days at <TEX>$28^{\circ}C$</TEX> after they were inoculated with selected strains such as Aspergillus otyzae (AO meju), Aspergillus sojae (AS meju), combined Aspergillus sojae and Bacillus subtilis (ASBS meju), and combined Aspergillus oryzae and Bacillus subtilis (AOBS meju) as starter microorganisms. The changes in the quality characteristics in the four kinds of meju were investigated during fermentation. Their enzyme activities were compared with those of the traditional meju that is made in Sunchang Folk Village according to the traditional method. In the meju that were inoculated with selective strains, the aerobic bacteria counts and mold counts exceeded 8 log cfu/g and 6 log cfu/g respectively, which were the highest fermentation values after 2 days. The aerobic bacteria counts were maintained from 2-day to the 12-day fermentation. The mold counts tended to decreased gradually after the 2-day fermentation. The amino-type nitrogen contents reached 430.5-577.5 mg%, which were the highest values after 2-day fermentation. The neutral protease activities of these mejus had the highest levels in the following order: traditional meju, <TEX>$1,258.0{\pm}38.8$</TEX>; AS meju, <TEX>$1,238.3{\pm}38.6$</TEX>; AO meju. <TEX>$1,204.1{\pm}24.1$</TEX>; ASBS meju, <TEX>$1,040.6{\pm}10.6$</TEX>; and AOBS meju, <TEX>$1,033.5{\pm}11.2$</TEX> unit/g. The acidic protease activities of these meju had the highest levels in the following order: AO meju, <TEX>$1,030.1{\pm}19.1$</TEX>, traditional meju, <TEX>$1,007.7{\pm}30.5$</TEX>; AS meju, <TEX>$990.9{\pm}25.0$</TEX>; AOBS meju, <TEX>$910.9{\pm}15.3$</TEX>; and ASBS meju, <TEX>$888.2{\pm}15.7$</TEX> unit/g.

The effect of mild Pulsed Electric Field (PEF) conditions on acid tolerance, bile tolerance, growth and protease activity of the Lactobacillus delbrueckii ssp. bulgaricus LB-12.

Pulsed electric field (PEF) processing involves the application of pulses of voltage for less than one second to fluid products placed between two electrodes. So this study was conducted for the quantitative assessments of mild PEF conditions on acid tolerance, growth, bile tolerance and protease activity of Lactobacillus delbrueckii ssp. bulgaricus LB-12. The control and PEF treated samples were prepared by inoculating 10 ml of freshly thawed culture of Lactobacillus delbrueckii ssp. bulgaricus LB-12 into 990 ml of sterile 0.1% (wt/v) peptone water and treated in a pilot plant PEF system (OSU-4M). The treatments were positive square unipolar pulse width of 3 μs, pulse period of 0.5 second, voltage of 1 kV/cm, delay time of 20 μs and flow rate of 60 ml/min at 40.5°C. The control was passed through the PEF system (60 ml/min) without receiving any pulsed electric field condition. The acid tolerance was determined every 30 minutes for 120 minutes of incubation in acidified MRS broth at pH 2. Growth was determined hourly for 25 hours of incubation at 37°C in MRS broth. The bile tolerance was determined hourly for 16 hours of incubation in MRS-Thio broth . Samples were plated in duplicates using pH modified Lactobacilli MRS agar. The petriplates were incubated anaerobically at 43C for 72 hours. Protease activity was determined by o-phthaldialdehyde (OPA) UV- spectrophotometric assay at 0, 12, 24, 36 and 48 hours of incubation of conducted. inoculated skim milk at 40°C. Three replications were The control. The stationary phase of the bacterium was between hours 10 and 18. Moreover significant experimental design was repeated measurements on complete randomized block, Replications were the blocks. Data were analyzed using Proc Mixed model of Statistical Analysis System (SAS).The viability of the control Lactobacillus delbrueckii ssp. bulgaricus LB-12 was lost after 30 minutes of incubation in acidified MRS broth (pH 2), whereas, the bacterium subjected to mild PEF treatment was acid tolerant until the end of 120 minutes of incubation. Mild PEF significantly improved acid tolerance of Lactobacillus delbrueckii ssp. bulgaricus LB-12. and the growth reached the logarithmic phase an hour earlier than the decrease

In vitro differential activity of phospholipases and acid proteinases of clinical isolates of Candida

Candida yeasts are commensals; however, if the balance of normal flora is disrupted or the immune defenses are compromised, Candida species can cause disease manifestations. Several attributes contribute to the virulence and pathogenicity of Candida, including the production of extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate the in vitro activity of phospholipases and acid proteinases in clinical isolates of Candida spp. Eighty-two isolates from hospitalized patients collected from various sites of origin were analyzed. Phospholipase production was performed in egg yolk medium and the production of proteinase was verified in a medium containing bovine serum albumin. The study was performed in triplicate. Fifty-six (68.3%) of isolates tested were phospholipase positive and 16 (44.4%) were positive for proteinase activity. C. tropicalis was the species with the highest number of positive isolates for phospholipase (91.7%). Statistically significant differences were observed in relation to production of phospholipases among species(p<0,0001) and among the strains from different sites of origin (p=0.014). Regarding the production of acid protease, the isolates of C. parapsilosis tested presented a larger number of producers (69.2%). Among the species analyzed, the percentage of protease producing isolates did not differ statistically (χ2=1.9 p=0.5901 (χ2=1.9 p=0.5901). The majority of C. non-albicans and all C. albicans isolates were great producers of hydrolytic enzymes and,consequently, might be able to cause infection under favorable conditions.

Purification and some properties of an extracellular acid protease from Aspergillus clavatus

Acid proteases represent an important group of enzymes, widely used in food, beverage and pharmaceutical industries. For most of these applications the enzymatic preparation must be at least partially purified and free of substances that could change the characteristics of the product or the process. Fungal proteases have replaced other sources because they are easily obtained mainly from Mucor, Rhizopus, PenicilliumandAspergillus species. A strain of Aspergillusclavatus was selected by producing high level of acid protease activity. An extracellular aspartatic protease from this strain was purified 37.2 times with 37% recovery using (NH4)2SO4 fractionation and ion-exchange chromatography. The enzyme was found to be monomeric having a molecular mass of 30.4 kDa. The purified enzyme is an acid protease with optimum pH of 5.5 and temperature for optimum activity of 50 °C. Its high pH stability was verified in the range of 3.5–6.5. The acid protease was strongly inhibited by Hg+2 and partially inhibited by Cu+2, Zn+2 and Mn+2. The enzyme was sensitive to denaturing agent SDS and activated by thiol-containing reducing agent dithiotreitol (DTT). The protease activity was not influenced by iodoacetic acid, E-64 and PMSF, while it was lightly actived by EDTA and totally inhibited by pepstatin, with a Ki of 7.8 μM, indicating that is an aspartic protease. A.clavatus acid protease presents interesting characteristics for biotechnological process, such as cheese and flavor manufacture and dietary supplements, in which activity and stability in acid pH are required.

Disruption of the acid protease gene in Saccharomycopsis fibuligera A11 enhances amylolytic activity and stability as well as trehalose accumulation

The acid protease gene in Saccharomycopsis fibuligera A11 was disrupted by integrating the HPT (hygromycin B phosphotransferase) gene into ORF (Open Reading Frame) of the acid protease gene. The mutant 12 obtained could grow in the medium containing hygromycin. No clear zone formed by the mutant grown on the plate containing milk protein was observed whereas a big clear zone formed by the strain A11 was detected. The acid protease and amylases activities produced by the mutant within 3 days were 0.89 U/ml and 424.7 U/ml, respectively while those produced by the strain A11 were 13.5 U/ml and 259.9 U/ml, respectively. The amylases preparations produced by the mutant 12 and the strain A11 kept 88.8% and 45.5% of amylase activity, respectively after they were incubated at 37 °C for two days. Trehalose amount accumulated in the mutant cells was 28.3% (w/w) while that accumulated in the cells of S. fibuligera A11 was 23.6 (w/w).

Dietary modulation of digestive enzymes by the administration of feed additives to rainbow trout, Oncorhynchus mykiss Walbaum

The aim of this study was to assess the metabolic and digestive enzyme activities in rainbow trout, Oncorhynchus mykiss Walbaum fed dietary supplements. The biometric indices and the following enzymes activities were measured: acid protease and pepsin from the stomach homogenates, alkaline phosphatase (AP) from the small intestine and the brush border membrane, total proteolytic enzymes and trypsin from the small intestine and liver/pancreas. Dietary garlic induced a higher pepsin activity in the stomach than lipopolysaccharide (LPS) and ginger. Conversely, dietary ginger and LPS showed a significant difference (P > 0.05) in acid protease activity compared to the controls. There was not any significant difference observed between treated groups and the controls for hepato-pancreas proteolytic enzyme activity, except for trypsin. AP activity increased significantly with dietary garlic, ginger and LPS compared to the controls.

Early Weaning of Sea Bass (D. labrax) Larvae: Effects on Growth Performance and Digestive Enzyme Activities

In this study, effects of early weaning of sea bass (D. labrax) by microparticulate food on larval development and digestive enzyme activities, acid protease and alkaline protease were investigated until day 40. Larval rearing was conducted in closed sea water systems. Experiments were triplicated on 3 different weaning protocol that introduced on day 15 (MD15), day 20 (MD20) and day 25 (MD25) and also no microparticulate diet (MD) distributed in the control group. At the end of the experiment at 40-day, larval growth was calculated and the best values were obtained from MD25. Statistical differences among groups were not important (P>0.05) whereas MD15 was found different than the other groups (P 0.05) while control group was found statistically different (P<0.05). According to histological analysis, gastric glands and formation of functional stomach were observed on day 24-25 in all experimental groups. Acid protease activity firstly detected at 25 DAH. Control group was found different than the other groups (P<0.05). Finally, in terms of both growth parameters and survival rate and digestive enzyme activities it is clearly concluded that MD supplementation could be started after 25 DAH in D. labrax larviculture.

Biochemical and microbiological properties of Argentinean Patagonia soil with implanted forest species

The aim of the present study was to determine the effect of two implanted forest species with different vegetal residue chemical compositions on the biological and biochemical properties of soil. The study site was located in the INTA Forestal Station of Trevelin, Chubut, Argentina. Samples were extracted from soil in forest plots dominated by Radiata Pine (Pinus radiata D. Don.) or European Ash (Fraxinus excelsior L.). Microbial respiration, dehydrogenase activity, community-level physiological profile (CLPP) and index of microbial community functional diversity were used as biological parameters; and acid phosphatase, protease and β-glucosidase activities were employed as biochemical parameters. Microbial respiration, dehydrogenase and acid phosphatase activities showed greater values in soil under European Ash trees; however, significant differences in protease and β-glucosidase activities were not observed among species. The higher organic C content of soil under European Ash trees and lower lignin and greater N and P content of the leaves of European Ash trees could be responsible for the greater biological and biochemical activities observed in the soil. Principal component analysis (for PC1) showed significant differences in the physiology of microbial communities associated with these forest species. The Shannon-Weaver Index (H) of the functional diversity of microflora did not present significant differences among forest species.

A preliminary study of the protease activities in germinating brown rice (Oryza sativa L.)

Proteases hydrolyse storage proteins to provide precursors for perpetuating species. The aim of this study was to investigate and characterise different proteases in germinating brown rice. The protease activity of brown rice increased sevenfold during 7 days of germination. It was highest on day 6 when determined at pH 3.5. With casein as substrate the proteases showed two catalytic groups: acidic proteases with an optimal pH of 3.5 and alkaline proteases with an optimal pH of 8.0. The acidic protease activity was inhibited by Ba(2+) and Pb(2+) but stimulated by Zn(2+) , while the alkaline protease activity was inhibited by Ca(2+) and Pb(2+) but stimulated by Mg(2+) and Zn(2+) . SDS-gelatin-PAGE assay showed two protease activity bands at pH 3.5, while two different bands with higher molecular weights were observed at pH 8.0. Inhibition assay revealed that pepstatin A and E-64 inhibited 67.63 and 38.26% respectively of the protease activity at pH 3.5, indicating the presence of aspartic and cysteine proteases. Metalloproteases played a major role under alkaline conditions (88.37% inhibition with EDTA). Germinated brown rice proteases fall into different classes with different properties. This study is helpful for their further purification.

Digestive enzyme and alkaline phosphatase activities during the early stages of Silurus soldatovi development.

To provide a theoretical basis to improve the survival and growth rate and optimize diet of sheatfish (Silurus soldatovi), the activities of certain digestive enzymes and alkaline phosphatases were investigated during larval development of one-ten day old individuals. Results indicated that sheatfish larva (~ three days after hatching) had high levels of alkaline protease activity, which peaked at five days old and dipped by eight days old, although the trend was generally upward. Acid protease activity at one-eight days old was low, after which it increased rapidly. Amylase activity reached the highest value at five days old, after which it began to decline. Lipase activity fluctuated markedly and showed two peaks at three-four days old and six-eight days old. Larval digestive enzyme activity and alkaline phosphatase activity were higher when fed live food than when fed an artificial diet. Throughout the early development process, alkaline protease activity was higher than acid protease, alkaline protease and amylase specific activity decreased significantly for eight-day-old transition larvae, while acid protease activity increased rapidly. These results indicate that the changes in digestive enzyme activity were relevant to digestive function conversion during fish larvae development. Alkaline phosphatase activity showed an upward trend over the first ten days of life, which indicated that the gastrointestinal function of sheatfish improved gradually.

Quality characteristics of gochujang meju prepared with different fermentation tools and inoculation time of Aspergillus oryzae

To standardize a preparation method for traditional gochujang, 4 types of meju were prepared using different fermentation tools and inoculation time of Aspergillus oryzae with Bacillus subtilis. The acidic protease activities of the S-1 and S-2 were higher and significantly different than those of S-3 and S-4 on 8-day fermentation at 30°C. The free amino acid contents of the meju were high, in the order of S-2 (275.9 mg%, w/w) > S-1 (238.3 mg%) > S-3 (215.0 mg%) > S-4 (189.9 mg%). The amino-type nitrogen contents of the S-1 (355.6±12.3 unit/mL) and S-2 (327.0±5.8 unit/mL) were higher and significantly different than those of S-3 and S-4 on 4-day fermentation. However, no consistent differences were observed between S-1 and S-2 during the fermentation period. Therefore, we conclude that meju fermentation was largely affected by the inoculation time of A. oryzae rather than the fermentation tool (tray or net).

Breeding and identification of novel koji molds with high activity of acid protease by genome recombination between Aspergillus oryzae and Aspergillus niger

Acid protease is essential for degradation of proteins during soy sauce fermentation. To breed more suitable koji molds with high activity of acid protease, interspecific genome recombination between A. oryzae and A. niger was performed. Through stabilization with d-camphor and haploidization with benomyl, several stable fusants with higher activity of acid protease were obtained, showing different degrees of improvement in acid protease activity compared with the parental strain A. oryzae. In addition, analyses of mycelial morphology, expression profiles of extracellular proteins, esterase isoenzyme profiles, and random amplified polymorphic DNA (RAPD) were applied to identify the fusants through their phenotypic and genetic relationships. Morphology analysis of the mycelial shape of fusants indicated a phenotype intermediate between A. oryzae and A. niger. The profiles of extracellular proteins and esterase isoenzyme electrophoresis showed the occurrence of genome recombination during or after protoplast fusion. The dendrogram constructed from RAPD data revealed great heterogeneity, and genetic dissimilarity indices showed there were considerable differences between the fusants and their parental strains. This investigation suggests that genome recombination is a powerful tool for improvement of food-grade industrial strains. Furthermore, the presented strain improvement procedure will be applicable for widespread use for other industrial strains.

Fragmentation of a highly purified monoclonal antibody attributed to residual CHO cell protease activity

Monoclonal antibody (mAb) fragmentation can be a widespread problem across the biotechnology industry and there is a current need to better understand the underlying principles. Here, we report an example of a high-purity human IgG1 mAb prepared from CHO cells exhibiting fragmentation that can be attributed to residual proteolytic enzyme activity. The concomitant occurrence of proteolytic and non-proteolytic peptide bond cleavage is shown and the respective fragmentation patterns characterized using high-resolution LC-MS. Fragmentation rates are monitored by SE-HPLC and SDS-PAGE over the pH range 4-6 and characterized in the presence and absence of pepstatin A, an inhibitor of acidic proteases. After 20 days at 40°C, pH 4, ∼60% decrease in BIIB-mAb monomer peak occurred attributed to residual proteolytic activity. At pH 5, this value was ∼13%. These results have implications for formulation design studies and the interpretation of accelerated stability data. A simple method to screen for acidic protease activity using the proteolytic enzyme inhibitor pepstatin A is described.

Optimum production and characterization of an acid protease from marine yeast Metschnikowia reukaufii W6b

The marine yeast strain W6b isolated from sediment of the South China Sea was found to produce a cell-bound acid protease. The crude acid protease produced by this marine yeast showed the highest activity at pH 3.5 and 40 °C. The optimal pH and temperature for the crude acid protease were in agreement with those for acid protease produced by the terrestrial yeasts. The optimal medium of the acid protease production was seawater containing 1.0% glucose, 1.5% casein, and 0.5% yeast extract, and the optimal cultivation conditions of the acid protease production were pH 4.0, a temperature of 25 °C and a shaking speed of 140 rmin−1. Under the optimal conditions, 72.5 UmL−1 of acid protease activity could be obtained in cell suspension within 48 h of fermentation at shake flask level. The acid protease production was induced by high-molecular-weight nitrogen sources and repressed by low-molecular-weight nitrogen sources. Skimmed-milk-clotting test showed that the crude acid protease from the cell suspension of the yeast W6b had high skimmed milk coagulability. The acid protease produced by M. reukaufii W6b may have highly potential applications in cheese, food and fermentation industries.

Fluorometric determination of acid proteinase activity in Candida albicans strains from diabetic patients with vulvovaginal candidiasis

Vulvovaginal candidiasis is one of the most frequent disorders in obstetrics and gynaecology. Approximately three-quarters of all adult women experience at least one episode of vulvovaginal candidiasis during their life span. Diabetes mellitus (DM) increases the rate of vaginal colonisation and infection with Candida species. The secreted acid proteinase might be especially relevant in the pathogenesis of vulvovaginal candidiasis. The aim of this study was to determine the acid proteinase activity in the samples of Candida albicans from diabetic patients with vulvovaginal candidiasis by a fluorometric method. Vaginal swabs were taken from 33 women (aged between 22 and 57 years) having symptoms of vaginitis. Patients were divided into three groups: control group, controlled diabetic group and uncontrolled diabetic group. The proteinase activity in the culture supernatants was determined by a modified fluorometric method. Acid proteinase activities were significantly increased in the uncontrolled diabetic group in comparison with both the control group and the controlled diabetic group (P < 0.05). Acid proteinase may play an important role in C. albicans pathogenesis in diabetic patients. Improving glucose control may reduce the risk of Candida colonisation and potentially symptomatic infection, among women with diabetes and hence may be useful even for weaker enzyme activity measurements.

PRODUCTION OF MONASCUS PURPUREUS PIGMENTS; INFLUENCED BY AMIDASE AND ACID PROTEASE ACTIVITY

Monascus purpureus grown on rice secretes several polyketide pigments used for coloring foods. The amidase enzymes, L-asparaginase and L-glutaminase activities were identified by rapid plate assay. The pink zone formed around colonies of M. purpureus (Microbial Type Culture Collection [MTCC] 410), hyper pigment (Central Food Research [CFR] 410-11) and albino (CFR 410-22) were 2.0, 2.4 and 1.2 cm, respectively. The L-asparaginase (0.103 IU) and L-glutaminase (0.139 IU) activity was comparatively more in CFR 410-11 than MTCC 410 and CFR 410-22. Higher acid protease activity (5,170 Units) was observed in CFR 410-22. The mutant CFR 410-11 has secreted more red pigment cultured on rice (2.248 optical density [OD] units) and in broth (0.841 OD units). Significant difference in amidase and acid protease activities of MTCC 410 and its mutant CFR 410-11 and CFR 410-22 have revealed the importance of these enzymes in pigment production. PRACTICAL APPLICATION The isolated albino (CFR 410-22) mutant has overproduced acid protease enzyme. This enzyme finds applications in debittering of protein hydrolysate, cheese ripening and preparation of amino acid mixture from protein. The amidase enzymes produced by Monascus sp. may play a major role in tumor inhibition.

Effects of shade on free amino acid composition, arginase and protease activities in the mulberry tree, Morus spp.

Effects of shade on free amino acid composition, arginase and protease activities in the mulberry tree, Morus spp.

Feeding time synchronises daily rhythms of behaviour and digestive physiology in gilthead seabream ( Sparus aurata)

Feeding cycles entrain biological rhythms, which enables animals to anticipate feeding times and so maximizes food utilization. In this article the effect of mealtime on locomotor activity, blood glucose, gastric pH and digestive enzymes was studied in two groups of seabream ( Sparus aurata): one group received a single daily meal at random times either during the light or the dark (random feeding, RF), whereas the other group received the meal during the light period every day at the same time (periodic feeding, PF). PF fish showed strong synchronisation of locomotor activity to the light phase (97.9 ± 0.2% of their total daily activity during daytime). In addition, the locomotor activity rhythm of PF fish showed a statistically significant daily rhythm (p < 0.05) for a period of 24 h, whereas RF fish did not display a statistically significant rhythm. Blood glucose levels were higher in RF fish during the 8 h following feeding. Gastric pH showed a postprandial decrease in both groups, but RF fish showed a lower daily average value (4.31 ± 0.21 compared with 5.52 ± 0.20). Amylase and alkaline protease activity increased some hours before mealtime in PF fish, whereas amylase activity increased 1 h after feeding and alkaline protease showed no statistically significant differences in RF fish. Acid protease activity showed no statistically significant differences in any group. Taken together, these results demonstrate that altering the feeding time affects the physiology and behaviour of seabream, which have the capacity to prepare themselves for a forthcoming meal.