Recovery of Chitin and Protein from Shrimp Head Waste by Endogenous Enzyme Autolysis and Fermentation

The industrial processing of shrimp produces massive quantities of solid waste that is a notable source of animal protein, chitin, carotenoids, and other bioactive compounds that are not appropriately utilized. In the present study, chitin and protein extraction from shrimp head with autolysis and fermentation using Bacillus licheniformis were investigated. The results showed that when shrimp heads were autolyzed with a natural pH at 50℃ for 4 h, the total amino acid nitrogen in the supernatant was 5.01 mg mL^-1. Then, when a 50%(v/m) inoculum of the hydrolysate was incubated at 60℃ for 10 h, a deproteinization rate of 88.3% could be obtained. The fermented supernatant was processed into a dry protein powder, while the residues were demineralized by 10% citric acid for chitin. The recovered protein powder contained 5.5% moisture, 11.5% ash, and 66.7% protein, while the chitin contained 3.5% moisture, 2.1% ash, and 3.1% protein. In addition, amino acids, minerals, heavy metals, the degree of acetylation, microstructure, and Fourier-transform infrared(FT-IR) spectroscopy results were analyzed. Furthermore, the statistics of the large scale trial after treatment with 20 kg of shrimp heads were analyzed. Thus, this work made the shrimp waste utilization environmentally sound and valuable.

Discovery of a novel gene involved in autolysis of Clostridium cells

Cell a utolysis plays important physiological roles in the life cycle of clostridial cells.Unders tanding the genetic ba-sis of the autolysis phenomenon of pathogenic Clostridi-um or solvent producing Clostridium cells might provide new insights into this important species.Genes that might be involved in autolysis of Clostridium acetobutylicum,a model clostridial species,were investigated in this study.Twelve putative autolysin genes were predicted in C.ace-tobutylicum DSM 1731 genome through bioinformatics analysis.Of these 12 genes,gene SMB_G3117 was select-ed for testing the in tracellular autolysin activity,growth profi le,viable cell numbers,and cellular morphology.We found that overexpression of SMB_G3117 gene led to earlier ceased growth,signifi cantly increased number of dead cells,and clear electrolucent cavities,while disrup-tion of SMB_G3117 gene exhibited remarkably reduced intracellular autolysin activity.These results indicate that SMB_G3117 is a novel gene involved in cellular autolysis of C.acetobutylicum.

Influence of Freezing and Freeze Drying on Intracellular Enzymatic Activity and Autolytic Properties of Some Lactic Acid Bacterial Strains

Lactic acid bacteria possess several interesting properties of great economic importance. Improvement and stabilization of these industrially important features are an active research area at the present time. The objectives of this work are to study the effect of freezing and freeze-drying on the survival rate, autolytic activity and intracellular enzymatic activity of the main species of lactic acid bacteria used in the dairy industry. The article focused on several characteristics that were not well covered in the past. The obtained results revealed that both preservation methods have a significant effect on viability, autolytic activity and intracellular enzymatic activity. After six months of storage we found that frozen cultures exhibited higher survival rate, higher rate of intracellular enzymatic activity and lower rate of autolysis. The impact of conservation treatments was only strain specific in the case of survival rate. The results obtained lead to the selection of the best preservation method for the selected cultures based on survival rate, autolytic activity and intracellular enzymatic activity.

Autolytic and Proteolytic Properties of Strains of<i>Lactococcus lactis</i>Isolated from Different Vegetables, Raw-Milk Cheeses and Commercial Starter Cultures

The autolysis and proteolysis are important features in the strains of L. lactis used in the manufacture of cheese. The autolytic and proteolytic activity of L. lactis has been linked with the development of flavor and texture in the cheese. On the other hand, there is a growing interest in new strains isolated from raw-milk cheeses and vegetables. These wild-strains have showed different features of industrial importance in comparison with those observed in commercial cultures. However, it still not clear if the autolytic and proteolytic properties of these wild-strains differ from the industrial strains. The objective of this work was to assess the autolytic and proteolytic activities of 21 strains of L. lactis isolated from diverse sources. The rates of autolysis and proteolysis observed in vitro were highly strain-dependent. The pH and the NaCl concentration in the media affected significantly the autolysis of L. lactis. The strains isolated from vegetable showed in general low and medium autolytic activity, whereas the strains isolated from raw-milk cheeses had medium to high autolytic activity. The strain with highest proteolytic activity was a strain isolated from corn leaves. Although still not clear how this strain acquired this pronounced characteristic.

Over-Production of P60 Family Proteins, Glycolytic and Stress Response Proteins Characterizes the Autolytic Profile of <i>Listeria monocytogenes</i>

Listeria monocytogenes is a foodborne pathogen capable of surviving under challenging conditions both outside and inside the host. During the transition from exponential to stationary phase it experiences a series of environmental changes that require an appropriate response to maintain cell viability. In this study the autolytic behaviour of a L. monocytogenes strain was investigated by two-dimensional electrophoresis. The study was done at the permissive autolysis temperature, 30℃ and at 20℃, an autolysis non-permissive temperature. An autolytic strain proteome was also compared to a non-autolytic strain at the permissive autolysis temperature. The autolytic strain proteome at 30℃ in comparison to 20℃ evidenced increased synthesis of the P60 autolysin, glycolytic enzymes and proteins related with environmental stress responses. The over-production of P45 autolysin, was observed when the autolytic strain proteome was compared with the non-autolytic strain. The proteomes at the non-permissive temperature and the proteome of the non-autolytic strain were characterized by a diminished synthesis of several stress related proteins. The lack of autolysis seems to be associated to the over-production of proteins linked to fatty acid and amino acid synthesis, transcription regulation and cell morphogenesis as evidenced by the proteome at the non-permissive temperature and the non-autolytic strain. Autolysis proteome evidenced the over-production of P60 autolysins, glycolysis and stress proteins whereas the proteome obtained in conditions of absence of autolysis reveal a completely different group of proteins. Possible targets to activate listerial autolysis were identified.

Endoscopic profile of caustic burns of the university hospital center of Cocody Abidjan / Côte d’Ivoire

Background:To determine the clinical and endoscopic demographic characteristics of the ingestion of acidic products in the digestive endoscopy unit of the Cocody University Hospital.Methods:This was a retrospective,descriptive and analytical study on endoscopic reports,which took place for five years,from January 1,2014,to December 31,2018.All patients were admitted to the digestive endoscopy unit with the indication of ingestion of caustic products.The parameters studied:are demographic,clinical,and endoscopic.The statistical tests used were Pearson’s CHI 2 and Fisher’s exact tests.The significance threshold was set at 5%.Results:83 patients were included for an endoscopic prevalence of 1.33%.The mean age was 20.77±16.58 years,with extremes ranging from 1 to 63 years.They were divided into 34 men and 49 women for a sex ratio of 0.69.Accidental circumstances were observed in 73.49%of cases,followed by attempted autolysis(26.51%).Bleach was the most offending caustic(75.90%),followed by hydrochloric acid(14.46%).FOGD was normal in 53.01%and revealed stage I(41.54%)digestive lesions,followed by stage II(35.39%)and stage III(21.53%).The lesions were preferentially gastric(36.11%),esogastroduodenal(27.78%),and esogastric(22.23%).Based on severity,54.55%of esophageal lesions were stage IIA,53.12%were stage I gastric lesions,and 54.55%were stage IIA duodenal lesions.One case of gastric perforation was noted(1.54%).In univariate analysis,we found a statistically significant link between the age group of 1–14 years and the accidental intake of caustics(P<0.001)on the one hand and the other hand between the age group of 26 years and over and taking for autolysis(P=0.02).Likewise,bleaching was responsible for less severe lesions(P=0.006).Conclusions:The seriousness of the ingestion of caustic products requires early,specialized and multidisciplinary management to improve the short,medium,and long-term prognosis of patients.

Use of dry yeast cells as a cheap nitrogen source for lactic acid production by thermophilic Bacillus coagulans WCPIO-4

Dry yeast cells （DYC） were used as a cheap nitrogen source to replace expensive yeast extract （YE） for L-lactic acid production by thermophilic Bacillus coagulans. Cassava starch （200 g. L1） was converted to L-lactic acid by simultaneous saccharification and fermentation using Bacillus coagulans WCP10-4 at 50℃ in the presence of 20g·L-1 of DYC, giving 148.1 g·L-1 of L- lactic acid at 27 h with a productivity of 5.5 g·L-1·h-1 and a yield of 92%. In contrast, 154.4 g·L-1 of lactic acid was produced at 24 h with a productivity of 6.4 g·L-1. hl and a yield of 96% when equal amount of YE was used under the same conditions. Use of pre-autolyzed DYC at 50℃ for overnight slightly improved the lactic acid titer （154.5g·L-1） and productivity （7.7g·L-1·h-1） but gave the same yield （96%）.

Reciprocity Effect between Silicate Bacteria and Wollastonite

This paper studied the reciprocity effect between wollastonite and a strain silicate bacterium from purple soil. We analyzed the changes of pH value, glucose (GLU) residual concentration, electrolyte and Mn, Si, Fe etc. in the culture liquid with wollastonite after 48 h. The results show that the GLU wastage of silicate bacteria with wollastonite is 2.5 times of the bacterial contrast. It showed wollastonite could obviously accelerate silicate bacteria growth, but bacterial cell broken and distorted badly have been found by SEM analysis. The solubilization of silicate bacteria to Si element of wollastonite reached above 10 times. At the same time, three apices in FTIR of wollastonite (898 cm-1, 925 cm-1, 962 cm-1) descended obviously after the action of silicate bacteria, which shows that a great deal of Si has dissolved out. So we can get that wollastonite has remarkable effect to the growth of silicate bacteria and silicate bacteria has obvious solubilization to Si of wollastonite.

Biochemical analysis of granzyme H and elucidation of its structurally important residues involved in substrate and inhibitor binding

Apoptotic cell death plays an important role in the maintenance of the normal physiological state and in the pathogenesis of diseases.Granule exocytosis is the main pathway for the immune elimination of virus-infected cells and tumor cells by cytotoxic T lymphocytes and natural killer cells.In recent study,we have investigated the level of granzyme H in patients with breast cancer and in control subjects using enzymatic method.Our study also included the prediction of different sites of granzyme H that play a role in substrate and inhibitor recognition in apoptosis process by using 3D structural model of the enzyme.The research described the possible post-translational modification sites that may help the enzyme in immune elimination of tumor cells.Our study shows that the level of granzyme H was reduced in patients when compared to normal control subjects.There are a number of amino acids that function as substrate recognition sites in granzyme H.However,inhibitors may inhibit their activity and affect the process of autolysis.