α-Amylase Production on Low-Cost Substrates by Naxibacter sp. Isolated from Mauritian Soils.

Alpha amylase is an important enzyme used in different industries, which degrades starch into smaller disaccharides. Extracellular α-amylase producing organisms were isolated from soil samples from Mauritius and identified by standard biochemical tests. In this study, the high yielding strain was used for amylase production. The potential of four readily available substrates, namely sugarcane bagasse, potato peel, kitchen wastes and banana peel to induce amylase production was investigated. Different parameters like temperature (30ºC, 40ºC, 50ºC, 60ºC & 70ºC), different pH (5.0, 6.0, 7.0, 8.0 & 9.0) and inoculum sizes (10%, 20%, 50%, 100% & 150% v/w) were used for the α-amylase production. It was found that α-amylase production and activity was highest for potato peel at 50ºC at pH 6.0 and inoculum size 50% (v/w). Amylase assays performed at different incubation temperatures (30ºC - 60ºC) and pH (5-9) showed that the amylase worked best at 50ºC and pH 7.Based on results of biochemical tests and 16S ribosomal RNA gene sequences, the isolate was identified to belong to the Betaproteobacteria, closely related to Naxibacter haematophilus (99% sequence similarity to the type strain).

Solid substrate fermentation of cassava fibrous residue for production of alpha-amylase, lactic acid and ethanol.

There is serious concern about the disposal of solid residues left after large scale extraction of starch from cassava. Owing to the high starch content (55-65% on dry weight basis) and organic matter of these wastes, an attempt has been made to utilize it for the production of three bioproducts, i.e. alpha-amylase, lactic acid and ethanol in solid substrate fermentation by incubating the solid residue at different moisture holding capacity (40-80%) and incubation period (12- 60 hr for alpha-amylase, 24-144 hr for ethanol and 2-10 days for lactic acid). The highest product yield was obtained at 60% moisture holding capacity of the residue and period of incubation varied from 36 hr (alpha-amylase), 120 hr (ethanol) to 6 days (lactic acid). This study showed that the solid residues from cassava starch factories could serve as a low-cost substrate for bioproducts production.

Production of amylases by Aspergillus tamarii

A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both Ó-amylase and glucoamylase activities in mineral media supplemented with 1(per cent) (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42degree C). Two amylases, once Ó-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50(degree) and 60(degree) C and wete stable for more than ten hours at 55(degree) C.

Production of alph-amylase in acid cheese whey culture media with automatic pH control

The influence of aeration and automatic pH control on the production of alpha-amylase by a strain of "Bacillus subtilis" NRRL 3411 from acid cheese whey was studied. Tests were carried out in a rotary shaker and in mechanically stirred ferments. Alpha-maylase was analysed according to DUN's method. Oxygen absorption rate was determined by Cooper's method. Cell oxygen demand was determined as oxygen consumption in a Warburg respirometer. The level of dissolved oxygen was mesured by means of a galvanic silver-lead electrode. Results suggest the possibility of industrial use of acid cheese whey as a carbon source for alpha-amylase production, since the yiels was similar to that produced with lactose. The highest alpha-amylase levels 100,000 DUN/ml units were not attained at highr aeration rates -431 mLO2/L.h-. The indicated value correspond to a 96 h process with automatic pH enzyme production was directly related to growth in the form of cell aggregates.

Thermostable alpha-amylase production using Bacillus licheniformis NRRL B14368.

Maximum amount of extracellular alpha-amylase of B. licheniformis NRRL B14368 was obtained at the stationary phase. Highest yield of alpha-amylase was achieved with high level of crude protein and low carbohydrate level. There was a catabolite repression in the organism. Protease was produced concurrently with alpha-amylase. It was also observed that soyabean acts as an inhibitor of the protease. Optimum pH and temperature of alpha-amylase were 5-7 and 76 degrees C respectively. It was also observed that alpha-amylase production was a non-growth associated product. Maltose was an excellent inducer for alpha-amylase production. Ca2+ (0.01 M) increased the thermostability of the enzyme. Alpha-amylase purification studies were carried out by using isopropanol, acetone, ammonium sulphate solution, ion exchange chromatography. Acetone was found most suitable for the separation of alpha-amylase. Protein recovery and relative enzyme activity (as compared to that of the maximum activity of the crude enzyme) were 30.77% and 3.03 respectively.

O-Amylase isolated from Streptomyces II Culture conditions for amylase biosynthesis by Streptomyces lipmanii-ZAG-37

Streptomyces lipmanii-ZAG-37 was grown on nutrient agar medium supplemented by 2.0% starch. The growth was used for inoculating a sterile nutrient medium of pH 7.5, incubated without shaking for 6 days at 30°. Starch is the best carbon source among the tested carbohydrates, whereas potassium nitrate and potassium dibasic phosphate are the most suitable nitrogen and phosphate sources for the enzyme bio-synthesis. On the other hand nickel salts have an inhibtory action. Riboflavin stimulated the enzyme biosynthesis when different water soluble vitamins were tested. Maximum activity for the purified enzyme was recorded at 37° for 60 min. after which the activity was decreased. Amylase showed maximum activity in presence of starch followed by dextrin then glycogen. The activity of amylase was increased by 6.0 and 9.0% in prersence of strontium and calcium salts

Induction and regulation of alpha-amylase synthesis in a cellulolytic thermophilic fungus Myceliophthora thermophila D14 (ATCC 48104).

The alpha-amylase enzyme synthesis was higher when M. thermophila D-14 (ATCC 48104) was grown in culture medium incorporated with starch or other carbohydrates containing maltose units. Maximum enzyme production was attained with 1% starch followed by a gradual decrease with increasing concentration. Marked decrease in alpha-amylase synthesis occurred with the addition of glucose to the culture medium and this decreasing activity was proportional to the concentration of glucose. The enzyme synthesis was resumed as soon as the glucose concentration fell below a critical level. The addition of cAMP did not eliminate the repressive activity of glucose. The findings suggest that extracellular alpha-amylase synthesis in M. thermophila D-14 was inducible and subject to catabolite repression.

Obtención de *-amilasa bacteriana: influencia del shock térmico y de los nutrientes del medio / Isolation of baceterial *-amylase: effect of heat shock and media nutrients

Se estudió la producción de alfa-amilasa empleando una cepa de Bacillus subtilis NRRL 3411. Las variables estudiadas incluyeron shock término, concentración y naturaleza de la fuente de carbono, nitrógeno y factores. Además se realizaron experiencias sobre estabilización de los caldos enzimáticos libres de células. Se determinó que utilizando esporos sometidos a un shock térmico de 100-C de 10 min, en un medio con lactosa, caseína, extracto de levadura y minerales, se alcanzaron valores de 140 unidades de alfa-amilasa en 72 h de proceso. También se demostró que el agregado de 20% de glicerol y 1% de benzoato de sodio aseguran caldos estabilizados a 20-C, por un período de 30 días

Produçäo de *-amilase: características morfofisiológicas do B. amyloliquefaciens visando ao melhoramento genético / Production of *-amylase: morphophysiological characteristics of B. amyloliquefaciens in view to genetic improvement

Foram estudadas algumas características morfológicas e fisiológicas do B. amyloliquefaciens ATCC 23842 visando ao melhoramento genético da linhagem para o aumento da produçäo de alfa-amilase. A linhagem mostrou bom crescimento em meio ágar nutriente, apresentando tempo de geraçäo de 49,2 minutos. Neste meio, o Bacillus apresentou menor secreçäo de muco e cadeia contendo de 4 a 6 células, independentemente da fase de crescimento. Em meio mínimo, contendo amido solúvel como substrato, a produçäo de enzima iniciou-se após quatro horas de incubaçäo, coincidindo com a fase logarítmica de crescimento. De 8 a 12 horas de incubaçäo observou-se um aumento na concentraçäo da enzima enquanto a concentraçäo de açúcares redutores permanecu constante. Verificou-se que a luz ultravioleta näo se mostrou adequada para a obtençäo de mutantes com maior capacidade de síntese da enzima, provavelmente em virtude das características morfológicas apresentadas pela linhagem, que dificultaram uma absorçäo uniforme da radiaçäo. Estudo realizados para detecçäo de plasmídos, por meio de eletroforese em gel de agarose a 1% revelaram a ausência desses elementos

Melhoramento de Bacillus amyloliquefaciens por DNA transformante e fusäo de protoplastos para produçäo de amilase e proteases / Improvement of Bacillus amyloliquefaciens by DNA transformation and protoplasts fusion for amylase and proteases production

Utilizando-se Bacillus amyloliquefaciens ATCC 2342 e o B. natto, isolado do produto comercial "natto", respectivamente, bons produtores de alfa-amilase e proteases, conseguiu-se aumentar os níveis de produçäo destas enzimas através das técnicas de DNA transformante e fusäo de protoplastos. O melhoramento genético por transformaçäo foi mais eficiente do que aquele por fusäo de protoplastos