Biotechnological Processes in Microbial Amylase Production

Isolation and molecular identification of industrially important enzyme producer yeasts from tree barks and fruits

This study aimed to identify the yeast strains associated with the tree bark samples collected from the Aegean and Marmara regions and from rotten fruit samples. Fifty-one yeast strains were successfully isolated and screened for their abilities to produce industrially important extracellular enzymes. Thirty isolates demonstrated ability to produce at least two different enzymes and were selected for subsequent molecular identification using sequence analysis of ITS region and D1/D2 domain of the 26S rDNA. The most prevalent strains belonged to Papiliotrema laurentii (%23), Papiliotrema terrestris (%13) and Candida membranifaciens (%10). Papiliotrema laurentii and Papiliotrema terrestris recorded the highest enzymatic activities for all the screened enzymes. To the best of our knowledge, this is the first report that identifies the yeast strains associated with the tree barks of Turkey and among the limited comprehensive studies that screened considerable number of isolates for their ability to produce several industrially important enzymes.

Mannitol and erythritol reduce the ethanol yield during Chinese Baijiu production

Chinese Baijiu is prepared using multiple microbial strains and complex metabolites by simultaneous saccharification and fermentation (SSF). Yeasts are challenged by various endogenous and exogenous factors, detrimentally affecting the ethanol yield. It is imperative to identify and control inhibitory factors. In the present study, microbial taxa and metabolites during Baijiu fermentation were evaluated to identify inhibitors of ethanol production. We found that filamentous fungi and Bacillus, contributing to saccharification, were negatively related to the ethanol content (Spearman's |ρ| > 0.5, P < 0.05). To explore how they affect ethanol production, ten filamentous fungi and three Bacillus strains were isolated. In addition to glucose and maltose, polyols were simultaneously generated by filamentous fungi and Bacillus via the hydrolysis of starch, among which mannitol and erythritol had the highest contents of up to 41.56 ± 2.01 g/kg and 16.16 ± 1.13 g/kg, respectively. The presence of mannitol and erythritol inhibited ethanol production by the functional yeasts Saccharomyces cerevisiae and Pichia kudriavzevii. The presence of 10.0 g/L mannitol significantly (P < 0.01) decreased the ethanol yield of S. cerevisiae by 12.67% (from 39.34 ± 0.02% to 32.71 ± 0.49%). These results revealed that polyols may inhibit the production of Baijiu and other fermented foods, suggesting that the origin and influence of polyols should be a focus of future research.

Host associated mixed probiotic bacteria induced digestive enzymes in the gut of tiger shrimp Penaeus monodon

The shrimp Penaeus monodon was used for the isolation of digestive enzyme producing host-associated probiotic bacteria. Gut was isolated from a healthy animal completely and morphologically different bacterial isolates were screened for the production of hydrolytic enzymes, such as, protease, amylase, lipase and cellulases. Based on their ability to produce enzymes, the potent probiotic bacteria were identified as Bacillus subtilis and B. licheniformis and these two were used for the preparation of probiotic diet for experimental trials. Probiotic diet was prepared by mixing the shrimp feed with 2 g probiotic/100 g artificial diet (F1), 4 g/100 g (F2), 6 g/100 g (F3), 8 g/100 g (F4) and 10 g/100 g (F5). Juvenile shrimp was fed with probiotic and control diet for a period of 7 weeks at 5 and 8% body weight for the first 3 and 7 weeks, respectively. After seven weeks, whole gut was dissected out and protease activity was estimated as 145 ± 12.3 U/g in control animal and increased as 710 ± 15.2 U/ g in F5 feed groups. Amylase activity was 139 ± 10.4 U/g in control and increased as 209 ± 13. 3 U/g in F5 group. Cellulase activities were 171 ± 9.3 in F5 groups and the control group showed only 102 ± 12.4 U/g. Lipase activity was 78 ± 3 U/g in F1 groups and it increased as 85 ± 5 U/g in F3 groups. These findings indicate the potential of host-associated bacteria to enhance the production of enzymes in the gut of juvenile P. monodon.

Characteristics of Raw-Starch Degrading Amylase Bacteria from Natar Hot Spring Lampung

Indonesia has a diversity of hot spring as a habitat of bacteria. One of the hot springs is Natar hot spring, Lampung. This study is to report the characteristics of a bacterium called Nat1 isolate that produces amylase to degrade raw starch from Natar hot spring. Water samples were taken from hot springs with a temperature of 45°C and a pH of 7.0. Nat1 was isolated by screening on the medium of Starch-Luria Bertani at 37°C. Its amylase-producing bacteria showed an optimum amylolytic activity of a crude enzyme of Nat1 isolate in soluble starch was 267.2774 U/mL at 60°C. Genotypic identification results using the 16S rRNA gene showed that the Nat1 isolate is identified as Panninobacter phragmatetus. A crude enzyme of Nat1 isolate showed a novel amylase ability and could degrade the raw starch substrates, such as corn and sago, with the amount of reducing sugar for each raw starch, 37.0688 µmol/mg, and 24.2697 µmol/mg. In conclusion, Nat1 amylase is potentially used in industry for its ability to degrade raw starch directly.

The Lipase/Amylase Ratio (LAR) in Peripheral Blood Might Represent a Novel Prognostic Marker in Patients with Surgically Resectable Pancreatic Cancer

Pancreatic enzymes might play a pivotal role in the pathophysiology and prognosis of pancreatic cancer. The aim of this study is to investigate the lipase/amylase ratio (LAR), representing a marker previously used in the differentiation of pancreatitis, as a potential prognostic marker in pancreatic cancer. Data from 157 surgically treated patients with ductal pancreatic adenocarcinoma and 351 patients with metastatic disease were evaluated retrospectively. Cancer-specific survival (CSS) was considered the endpoint of the study. After applying Kaplan-Meier curve analysis, uni- and multivariate Cox regression models were calculated to evaluate the prognostic relevance of LAR. An elevated LAR at diagnosis of localized pancreatic cancer was significantly associated with higher CA19-9 levels (p < 0.05). In univariate analysis, we observed an increased LAR as a significant factor for lower CSS in localized pancreatic cancer patients (HR = 1.63; 95% CI = 1.12-2.36; p = 0.01), but not in metastatic patients (HR = 1.12; 95% CI = 0.87-1.43; p = 0.363). In multivariate analysis, including age, gender, tumor stage, Karnofsky Performance Status, tumor grade, administration of chemotherapy and the LAR, an increased LAR was confirmed to represent an independent prognostic factor regarding CSS (HR = 1.81; 95% CI = 1.17-2.77; p = 0.007) in localized pancreatic cancer patients. In conclusion, our study identified the LAR as an independent prognostic factor in surgically treated pancreatic cancer patients.

Purification and Characterization of Anabaena flos-aquae Phenylalanine Ammonia-Lyase as a Novel Approach for Myristicin Biotransformation

Phenylalanine ammonia-lyase (PAL) catalyzes the reversible deamination of phenylalanine to cinnamic acid and ammonia. Algae have been considered as biofactories for PAL production, however, biochemical characterization of PAL and its potency for myristicin biotransformation into MMDA (3-methoxy-4, 5-methylenedioxyamphetamine) has not been studied yet. Thus, PAL from Anabaena flos-aquae and Spirulina platensis has been purified, comparatively characterized and its affinity to transform myristicin was assessed. The specific activity of purified PAL from S. platensis (73.9 μmol/mg/min) and A. flos-aquae (30.5 μmol/mg/min) was increased by about 2.9 and 2.4 folds by gel-filtration comparing to their corresponding crude enzymes. Under denaturing-PAGE, a single proteineous band with a molecular mass of 64 kDa appeared for A. flos-aquae and S. platensis PAL. The biochemical properties of the purified PAL from both algal isolates were determined comparatively. The optimum temperature of S. platensis and A. flos-aquae PAL for forward or reverse activity was reported at 30°C, while the optimum pH for PAL enzyme isolated from A. flos-aquae was 8.9 for forward and reverse activities, and S. platensis PAL had maximum activities at pH 8.9 and 8 for forward and reverse reactions, respectively. Luckily, the purified PALs have the affinity to hydroaminate the myristicin to MMDA successfully in one step. Furthermore, a successful method for synthesis of MMDA from myristicin in two steps was also established. Gas chromatography-mass spectrometry (GC-MS) analysis was conducted to track the product formation.

A novel high maltose-forming α-amylase from Rhizomucor miehei and its application in the food industry

A novel α-amylase gene (RmAmyA) from Rhizomucor miehei was cloned and expressed in Pichia pastoris. RmAmyA showed 70% amino acid identity with the α-amylase from Rhizomucor pusillus. A high α-amylase activity of 29,794.2 U/mL was found through high cell density fermentation. The molecular mass of RmAmyA was determined to be 49.9 kDa via SDS-PAGE. RmAmyA was optimally active at 75 °C and pH 6.0, and it did not require Ca²⁺ to improve its activity. It exhibited broad substrate specificity towards amylose, amylopectin, soluble starch, pullulan, and cyclodextrins. High level of maltose (54%, w/w) was produced after liquefied starch was hydrolysed with RmAmyA for 16 h. Moreover, the addition of RmAmyA into Chinese steamed bread resulted in 7.7% increment in the specific volume, and 17.2% and 11.5% reduction in the chewiness and hardness, respectively. These results indicate that RmAmyA might be a potential candidate for applications in the food industry.

Multi-omic analyses of exogenous nutrient bag decomposition by the black morel Morchella importuna reveal sustained carbon acquisition and transferring

The black morel (Morchella importuna Kuo, O'Donnell and Volk) was once an uncultivable wild mushroom, until the development of exogenous nutrient bag (ENB), making its agricultural production quite feasible and stable. To date, how the nutritional acquisition of the morel mycelium is fulfilled to trigger its fruiting remains unknown. To investigate the mechanisms involved in ENB decomposition, the genome of a cultivable morel strain (M. importuna SCYDJ1-A1) was sequenced and the genes coding for the decay apparatus were identified. Expression of the encoded carbohydrate-active enzymes (CAZymes) was then analyzed by metatranscriptomics and metaproteomics in combination with biochemical assays. The results show that a diverse set of hydrolytic and redox CAZymes secreted by the morel mycelium is the main force driving the substrate decomposition. Plant polysaccharides such as starch and cellulose present in ENB substrate (wheat grains plus rice husks) were rapidly degraded, whereas triglycerides were accumulated initially and consumed later. ENB decomposition led to a rapid increase in the organic carbon content in the surface soil of the mushroom bed, which was thereafter consumed during morel fruiting. In contrast to the high carbon consumption, no significant acquisition of nitrogen was observed. Our findings contribute to an increasingly detailed portrait of molecular features triggering morel fruiting.

Marine Fungi: Biotechnological Perspectives from Deep-Hypersaline Anoxic Basins

Deep-sea hypersaline anoxic basins (DHABs) are one of the most hostile environments on Earth. Even though DHABs have hypersaline conditions, anoxia and high hydrostatic pressure, they host incredible microbial biodiversity. Among eukaryotes inhabiting these systems, recent studies demonstrated that fungi are a quantitatively relevant component. Here, fungi can benefit from the accumulation of large amounts of organic material. Marine fungi are also known to produce bioactive molecules. In particular, halophilic and halotolerant fungi are a reservoir of enzymes and secondary metabolites with valuable applications in industrial, pharmaceutical, and environmental biotechnology. Here we report that among the fungal taxa identified from the Mediterranean and Red Sea DHABs, halotolerant halophilic species belonging to the genera Aspergillus and Penicillium can be used or screened for enzymes and bioactive molecules. Fungi living in DHABs can extend our knowledge about the limits of life, and the discovery of new species and molecules from these environments can have high biotechnological potential.

Enhanced extracellular expression of Bacillus stearothermophilus α-amylase in Bacillus subtilis through signal peptide optimization, chaperone overexpression and α-amylase mutant selection

BACKGROUND

Our laboratory has constructed a Bacillus stearothermophilus α-amylase (AmyS) derivative with excellent enzymatic properties. Bacillus subtilis is generally regarded as safe and has excellent protein secretory capability, but heterologous extracellular production level of B. stearothermophilus α-amylase in B. subtilis is very low.

RESULTS

In this study, the extracellular production level of B. stearothermophilus α-amylase in B. subtilis was enhanced by signal peptide optimization, chaperone overexpression and α-amylase mutant selection. The α-amylase optimal signal peptide (SPYojL) was obtained by screening 173 B. subtilis signal peptides. Although the extracellular α-amylase activity that was produced by the resulting recombinant strain was 3.5-fold greater than that of the control, significant quantities of inclusion bodies were detected. Overexpressing intracellular molecular chaperones significantly reduced inclusion body formation and further increased α-amylase activity. Error-prone PCR produced an amylase mutant K82E/S405R (AmySA) with enzymatic activity superior to that of AmyS. Expression of the amySA gene with the SPYojL while overexpressing molecular chaperones resulted in a 7.1-fold improvement in α-amylase activity. When the final expression strain (WHS11YSA) was cultivated in a 3-L fermenter for 92 h, the α-amylase activity of the culture supernatant was 9201.1 U mL-1, which is the highest level that has been reported to date.

CONCLUSIONS

This is the first report that describes an improvement of B. stearothermophilus α-amylase extracellular production levels in B. subtilis using these strategies, and this represents the highest extracellular production level ever reported for α-amylase from B. stearothermophilus in B. subtilis. This high-level production provides a basis for enhanced industrial production of α-amylase. These extracellular production level improvement approaches are also expected to be valuable in the expression of other enzymes in B. subtilis.

Draft genome of Thermomonospora sp. CIT 1 (Thermomonosporaceae) and in silico evidence of its functional role in filter cake biomass deconstruction

The filter cake from sugar cane processing is rich in organic matter and nutrients, which favors the proliferation of microorganisms with potential to deconstruct plant biomass. From the metagenomic data of this material, we assembled a draft genome that was phylogenetically related to Thermomonospora curvata DSM 43183, which shows the functional and ecological importance of this bacterium in the filter cake. Thermomonospora is a gram-positive bacterium that produces cellulases in compost, and it can survive temperatures of 60 ºC. We identified a complete set of biomass depolymerizing enzymes in the draft genome of Thermomonospora sp. CIT 1, such as α-amylase, catalase-peroxidases, β-mannanase, and arabinanase, demonstrating the potential of this bacterium to deconstruct the components of starch, lignin, and hemicellulose. In addition, the draft genome of Thermomonospora sp. CIT 1 contains 18 genes that do not share identity with five other species of Thermomonospora, suggesting that this bacterium has different genetic characteristics than those present in genomes reported so far for this genus. These findings add a new dimension to the current understanding of the functional profile of this microorganism that inhabits agro-industrial waste, which may boost new gene discoveries and be of importance for application in the production of bioethanol.

Evolutionary Trends in Industrial Production of α-amylase

BACKGROUND

Amylase catalyzes the breakdown of long-chain carbohydrates to yield maltotriose, maltose, glucose and dextrin as end products. It is present in mammalian saliva and helps in digestion.

OBJECTIVE

Their applications in biotechnology include starch processing, biofuel, food, paper, textile and detergent industries, bioremediation of environmental pollutants and in clinical and medical applications. The commercial microbial strains for production of α-amylase are Bacillus subtilis, B. licheniformis, B. amyloliquefaciens and Aspergillus oryzae. Industrial production of enzymes requires high productivity and cannot use wild-type strains for enzyme production. The yield of enzyme from bacteria can be increased by varying the physiological and genetic properties of strains.

RESULTS

The genetic properties of a bacterium can be improved by enhancing the expression levels of the gene and secretion of the enzyme outside the cells, thereby improving the productivity by preventing degradation of enzymes. Overall, the strain for specific productivity should have the maximum ability for synthesis and secretion of an enzyme of interest. Genetic manipulation of α-amylase can also be used for the production of enzymes with different properties, for example, by recombinant DNA technology.

CONCLUSION

This review summarizes different techniques in the production of recombinant α- amylases along with the patents in this arena. The washing out of enzymes in reactions became a limitation in utilization of these enzymes in industries and hence immobilization of these enzymes becomes important. This paper also discusses the immobilization techniques for used α-amylases.

Elevated amylase in plasma represents an adverse prognostic marker in patients with metastatic pancreatic cancer : A retrospective analysis

Background and aim

The aim of this study was to investigate the prognostic relevance of plasma amylase and lipase concerning survival of patients suffering from metastatic pancreatic cancer (PC).

Method

This retrospective study included 351 patients with metastatic PC, who were treated in a single academic institution. Cancer-specific survival (CSS) was analyzed using the Kaplan-Meier method. To further evaluate the prognostic significance of lipase and amylase, univariate and multivariate values were calculated using Cox proportional models.

Results

In univariate analysis, an increased amylase level was associated with shorter CSS in PC patients (hazard ratio HR = 1.258; 95% confidence interval CI = 1.011–1.566; p = 0.039). In multivariate analysis, including gender, age, CA19-9 and administration of chemotherapy, increased amylase levels prevailed as an independent prognostic factor for CSS (HR = 1.373; 95%CI = 1.004–1.878; p = 0.047).

Conclusions

Plasma amylase was found to be an independent prognostic factor in patients with metastatic PC. The results indicate that amylase might represent a novel and useful marker for better patient stratification in PC management.

Purification and characterization of α-amylase from Trichoderma pseudokoningii

Background

Previous studies have demonstrated that members of Trichoderma are able to generate appreciable amount of extracellular amylase and glucoamylase on soluble potato starch. In this study the α-amylase was purified and characterized from Trichoderma pseudokoningii grown on orange peel under solid state fermentation (SSF).

Results

Five α-amylases A1-A5 from Trichodrma pseudokoningii were separated on DEAE-Sepharose column. The homogeneity of α-amylase A4 was detected after chromatography on Sephacryl S-200. α-Amylase A4 had molecular weight of 30 kDa by Sephacryl S-200 and SDS-PAGE. The enzyme had a broad pH optimum ranged from 4.5 to 8.5. The optimum temperature of A4 was 50 °C with high retention of its activity from 30 to 80 °C. The thermal stability of A4 was detected up to 50 °C and the enzyme was highly stable till 80 °C after 1 h incubation. All substrate analogues tested had amylase activity toward A4 ranged from 12 to 100% of its initial activity. The Km and Vmax values of A4 were 4 mg starch/ml and 0.74 μmol reducing sugar, respectively. The most of metals tested caused moderate inhibitory effect, except of Ca²⁺ and Mg²⁺ enhanced the activity. Hg²⁺ and Cd^+ 2 strongly inhibited the activity of A4. EDTA as metal chelator caused strong inhibitory effect.

Conclusions

The properties of the purified α-amylase A4 from T. pseudokoningii meet the prerequisites needed for several applications.