Amylolytic Microorganisms Research Articles

АГРОХИМИЧЕСКИЕ И БИОЛОГИЧЕСКИЕ СВОЙСТВА РИЗОСФЕРЫ СОИ ПРИ ПРИМЕНЕНИИ БАКТЕРИЗАЦИИ СЕМЯН

The aim of the study is to evaluate the effect of pre-sowing bacterization of soybean seeds with strains of the biopreparation Rizotorfin on the agrochemical and biological properties of the rhizosphere. The study was conducted in the conditions of the southern forest-steppe of Western Siberia. The object of the study was new varieties bred by the Omsk Agrarian Scientific Center – Sibiriada and Sibiriada 20. The soil of the experimental plot is meadow-chernozem medium-deep heavy loamy with a humus content of 6.5 %. The study of the microbial pool of the meadow-chernozem soil was carried out in a field experiment to evaluate the effect of pre-sowing bacterization of seeds on the agrochemical and biological pro¬perties of the soybean rhizosphere. In the root zone, the content of nitrate nitrogen (N-NO3), the number of agronomically significant groups of microorganisms, and the direction of soil-microbiological processes were determined. Against the background of the use of microbiological preparations, the amount of nitrate nitrogen did not change significantly. The changes in amylolytic and saprotrophic microflora are presented, reflecting the direction of soil-microbiological processes in the rhizosphere of soybean varieties, where immobilization processes were predominant. Inoculation of Sibiriada 20 soybean seeds with Rizotorfin promoted activation of the soil organic matter transformation process, the transformation coefficient varied from 61.0 to 132.7, reaching maximum values when using strain BP 835. In the root zone, a significant increase in saprotrophic microflora was observed in the Sibiriada 20 variety when bacterizing seeds with Rizotorfin, strain 634 (72 % of the control). Microorganisms of the tested group in the rhizosphere of the Sibiriada variety experienced depression when introducing strains of symbiotic nitrogen fixers into the soil, the decrease was 32 and 63 % of the control, which may be due to the genotypic characteristics of the varieties. The activity of amylolytic microorganisms changed with a tendency similar to saprotrophic bacteria. The highest efficiency of inoculation on the yield of soybean grain was noted in 2022. In the extremely dry conditions of 2023, a reliable effect of the bacterization factor on crop productivity was revealed. The most effective strain for the Sibiriada variety was BP 634 (+0.44 t/ha), for the Sibiriada 20 variety – strain BP 835 (+0.42 t/ha).

Amylolytic microorganisms from diverse tropical environments: Isolation, identification, and amylase production

AbstractThis study aimed to identify microbes producing amylases from diverse unexplored environments in Kenya. Screening based on microorganisms' ability to grow on minimal media (M9) supplemented with starch resulted in the selection of 70 amylolytic isolates. The isolates were then subjected to primary screening based on starch hydrolysis ratio (SHR) obtained by halo formation on starch agar plates after flooding plates with Lugol's iodine solution. SHR narrowed down the isolates' number to 17 (SHR > 1.5), which were used for subsequent experiments. The 17 isolates were grown on M9 starch broth for the production of amylases. Crude amylases and commercial enzyme (control) were assayed for amylase activity using the 3,5‐dinitrosalicylic acid method. Specific enzyme activities of crude enzymes ranged between 0.0079 and 0.0629 U g−1, which were lower than 1.7188 U g−1 of the control. Five enzymes with the highest specific enzyme activity were used for cassava hydrolysis. All crude enzymes exhibited higher specific enzyme activity (0.0707–0.1853 U g−1) than the control (0.0052 U g−1) in hydrolyzing cassava. Alkaline lakes had the highest number (4) of isolates whose enzymes had the highest specific enzyme activity, while isolates from potato processing plant waste, termite gut, and black soldier fly gut had a representative each. Isolates with enzymes having the highest specific enzyme activity were identified by DNA sequencing and belonged to Lysinibacillus sp. (four isolates), Alternaria sp. (one isolate), and Bacillus sp. (two isolates). The study demonstrated the presence of microorganisms in tropical environments with amylase activity that can be scaled and optimized for practical applications.

Rumen fluid handling affects measurements of its enzymatic activity and in vitro digestibility

Traditionally, rumen fluid without the particulate matter is used in in vitro studies, however, a higher concentration of rumen microbes is associated with particulate fraction than the liquid fraction of the rumen content. The objectives of this study were to determine if blending or sonication could increase the enzymatic activity of rumen fluid and to determine the effect of blending rumen fluid on in vitro digestibility of starch, neutral detergent fiber and protein when compared to filtration (control). Rumen fluid collected from two cannulated dairy cows was filtrated, blended or sonicated prior to enzymatic assay. In vitro digestibility of starch (7 h, corn), NDF (6, 12 and 24 h, oat hay) and nitrogen (16 h, soya oilcake) was determined. Both blending and sonication had the ability to consistently release more amylase, lichenase, endoglucanase and xylanase enzymes. Blending was not able to release more protease enzymes (P = 0.1515) and sonication cannot be replaced by blending for the extraction of cell-associated protease enzymes (P = 0.0322). For rumen in vitro digestibility, blending was not successful in liberating amylolytic microorganisms or enzymes associated with the particulate fraction and might have negatively affected the microbial population responsible for fiber and protein digestion. Therefore, as opposed to what is sometimes suggested, blending rumen fluid before an in vitro trial does not necessarily result in higher digestibility values and reduced lag (i.e. higher microbial activity) and could result in opposite results.

Effect of various salt concentrations on the ruminal parameters of goats

The objective of this study was to evaluate the effects of various concentrations of sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2) on the growth and in vitro fermentation of cellulolytic, glycolytic, and amylolytic microorganisms from the rumen of a goat. Six concentrations of each salt were tested separately, namely 0 mg/dL, 100 mg/dL, 200 mg/dL, 400 mg/dL, 800 mg/dL, and 1600 mg/dL in the culture medium. The experiments were conducted in a completely randomized design, in a 6 x 3 factorial arrangement of salt concentration and substrate (starch, cellulose, and glucose) with three replications of each treatment combination. Concentrations of microbial protein, ammonia (NH3-N), and volatile fatty acids (acetate, propionate, and butyrate) were measured. A quadratic effect of CaCl2 concentration on the production of microbial protein was observed in the cellulose medium. The effect of MgCl2 on NH3-N production in the cellulose medium decreased linearly. Propionate concentration decreased linearly with increasing levels of NaCl and MgCl2 in the media containing starch. There was a decreasing linear effect of MgCl2 on the concentration of butyrate in the media containing glucose. In conclusion, concentrations of NaCl and CaCl2 up to 1,600 mg/dL did not affect the microbial activity of starch, cellulose, and glucose-fermenting organisms. However, the microbial activity of starch-fermenting microbes was inhibited at salt concentrations above 800 mg/dL. Thus, brackish water could be used by goats in semiarid regions, but its use should be managed carefully so that it does not have a negative impact on rumen microbial populations.Keywords: cellulose, glucose, saline water, starch, ruminants

Ecotoxicity of soil contaminated with diesel fuel and biodiesel

Fuels and their components accumulate in soil, and many soil organisms are exposed to this pollution. Compared to intensive research on the effect of conventional fuel on soil, very few studies have been conducted on soil ecotoxicity of biofuels. Considering the limited information available, the present study evaluated the changes caused by the presence of biodiesel and diesel fuel in soil. The reaction of higher plants and soil organisms (microbial communities and invertebrates) was analysed. Conventional diesel oil and two types of biodiesel (commercial and laboratory-made) were introduced into the soil. Two levels of contamination were applied—5 and 15% (w/w per dry matter of soil). The plate method was used to enumerate microorganisms from soil contaminated with biodiesel and diesel fuel. Phytotoxicity tests were conducted by a 3-day bioassay based on the seed germination and root growth of higher plant species (Sorghum saccharatum and Sinapis alba). Fourteen-day ecotoxicity tests on earthworm were performed using Eisenia fetida. Based on the results of the conducted tests it was found out that the organisms reacted to the presence of fuels in a diverse manner. As to the microorganisms, both the growth and reduction of their number were noted. The reaction depended on the group of microorganisms, type of fuel and dose of contamination. The lipolytic and amylolytic microorganisms as well as Pseudomonas fluorescens bacteria were particularly sensitive to the presence of fuels, especially biodiesel. Fuels, even at a high dose, stimulated the growth of fungi. Monocotyledonous sugar sorghum plants were more sensitive to the presence of fuels than dicotyledonous white mustard. There was also a significant negative impact of contamination level on plant growth and development. Biodiesel, to a greater extent than conventional fuel, adversely affected the survival and volume of earthworms.

Development of a New Algorithm for Production of a Highly Efficient Biofertilizer From Peat–Manure Mixes

The All-Russia Research Institute of Reclaimed Lands has a long and fruitful history in development of biofertilizers and multifunctional biopreparations using directed bioconversion. This paper describes innovative elements of a fundamentally new technology for the production of a promising biofertilizer. The development of a new algorithm for bioconversion of peat–manure mixes is required for production of a competitive biofertilizer characterized by favorable acidity and a high content of beneficial microorganisms and bioavailable nutrients as well as for the choice of the most efficient bioconversion process. Three processes differing in their parameters have been compared in three repetitions via evaluation of the content of ammonifying and amylolytic microorganisms, sanitary microflora (enterobacteria), fungi, and actinomycetes in the initial peat–manure mixes and final products (variants of new biofertilizers); additionally, the activity of oxidoreductases and some agrochemical parameters have been compared. The algorithm of a fermentation process includes acid hydrolysis of the initial mix and two thermal stages. At the first stage (55–60°С for 24 h), the required ecological compatibility of a biofertilizer, characterized by the minimum presence of a sanitary microflora and spoilage fungi, is achieved. The second stage (36–39°С for 96 h) is characterized by an active development of microflora involved in the formation of the soil structure and fertility. In the course of the study, the optimum fermentation variant characterized by the maximum content of beneficial microflora, minimum content of enterobacteria, and a high content of key nutrients required for the plant growth (nitrogen, phosphorus, potassium) has been chosen.

Development of a new algorithm for obtaining highly effective bio-fertilizer from mixtures of peat and bird droppings

VNIIMZ has long and fruitfully been working on the creation of bio-fertilizers and multifunctional bio drugs produced by the method of directional bioconversion. This article reflects the innovative elements of a fundamentally new technology for producing promising bio-fertilizers. The development of a new bioconversion algorithm for peat and bird droppings mixtures was aimed at creating a competitive bio-fertilizer with favorable acidity, a high number of agronomically beneficial microflora, the presence of nutrients in a form available for plants and microflora, and was done by choosing the most effective bioconversion process. Compared 3 different process parameters, laid three times. Their assessment was carried out according to the content in the initial peat and bird droppings mixtures and in the final products (variants of the biological fertilizer) ammonifying and amylolytic microorganisms, sanitary indicative microflora (enterobacteria), fungi, actinomycetes, on the activity of oxidoreductases, on the level of agrochemical parameters. The algorithm for conducting the fermentation process includes acid hydrolysis of the initial mixture and two temperature stages. At the first stage, proceeding at 55-60С within 24 hours, the necessary ecological bio-fertilizer is achieved, characterized by a minimum of sanitary and representative microflora - enterobacteria and low content of spoilage microorganisms - fungal flora. At the second stage of bioconversion, occurring at a temperature of 36-39 С for 96 hours, the microflora actively develops, participating when using this fertilizer in the formation of soil structure, a high level of its effective fertility. During the development process, the choice was made of the option of conducting a fermentation process, which differs from the others by a higher content of agronomically beneficial microflora, a minimum of microorganisms of the genus Enterobacter and a high content of key nutrients (nitrogen, phosphorus, potassium) for plant growth.

Устойчивость микробиологической активности дерново-подзолистой почвы в условиях применения диатомита и цеолита

Устойчивость микробиологической активности дерново-подзолистой почвы в условиях применения диатомита и цеолита

Assessment of the toxicity of silicon nanooxide in relation to various components of the agroecosystem under the conditions of the model experiment.

Investigation of SiO2 nanoparticles (NPs) effect on Eisenia fetida showed no toxic effect of the metal at a concentration of 250, 500 and 1000mg per kg of soil, but conversely, a biomass increase from 23.5 to 29.5% (at the protein level decrease from 60 to 80%). The reaction of the earthworm organism fermentative system was expressed in the decrease in the level of superoxide dismutase (SOD) on the 14th day and in the increase in its activity to 27% on the 28th day. The catalase level (CAT) showed low activity at average element concentrations and increase by 39.4% at a dose of 1000mg/kg. Depression of malonic dialdehyde (MDA) was established at average concentrations of 11.2% and level increase up to 9.1% at a dose of 1000mg/kg with the prolongation of the effect up to 87.5% after 28-day exposure. The change in the microbiocenosis of the earthworm intestine was manifested by a decrease in the number of ammonifiers (by 42.01-78.9%), as well as in the number of amylolytic microorganisms (by 31.7-65.8%). When the dose of SiO2 NPs increased from 100 to 1000mg/kg, the number of Azotobacter increased (by 8.2-22.2%), while the number of cellulose-destroying microorganisms decreased to 71.4% at a maximum dose of 1000mg/kg. The effect of SiO2 NPs on Triticum aestivum L. was noted in the form of a slight suppression of seed germination (no more than 25%), an increase in the length of roots and aerial organs which generally resulted in an increase in plant biomass. Assessing the soil microorganisms' complex during introduction of metal into the germination medium of Triticum aestivum L., there was noted a decrease in the ammonifiers number (by 4.7-67.6%) with a maximum value at a dose of 1000mg/kg. The number of microorganisms using mineral nitrogen decreased by 29.5-69.5% with a simultaneous increase in the number at a dose of 50mg/kg (+ 20%). Depending on NP dose, there was an inhibition of the microscopic fungi development by 18.1-72.7% and an increase in the number of cellulose-destroying microorganisms. For all variants of the experiment, the activity of soil enzymes of the hydrolase and oxidoreductase classes was decreased.

Enhanced Bioethanol Production from Potato Peel Waste Via Consolidated Bioprocessing with Statistically Optimized Medium.

In this study, an extensive screening was undertaken to isolate some amylolytic microorganisms capable of producing bioethanol from starchy biomass through Consolidated Bioprocessing (CBP). A total of 28 amylolytic microorganisms were isolated, from which 5 isolates were selected based on high α-amylase and glucoamylase activities and identified as Candida wangnamkhiaoensis, Hyphopichia pseudoburtonii (2 isolates), Wickerhamia sp., and Streptomyces drozdowiczii based on 26S rDNA and 16S rDNA sequencing. Wickerhamia sp. showed the highest ethanol production (30.4g/L) with fermentation yield of 0.3g ethanol/g starch. Then, a low cost starchy waste, potato peel waste (PPW) was used as a carbon source to produce ethanol by Wickerhamia sp. Finally, in order to obtain maximum ethanol production from PPW, a fermentation medium was statistically designed. The effect of various medium ingredients was evaluated initially by Plackett-Burman design (PBD), where malt extracts, tryptone, and KH2PO4 showed significantly positive effect (p value <0.05). Using Response Surface Modeling (RSM), 40g/L (dry basis) PPW and 25g/L malt extract were found optimum and yielded 21.7g/L ethanol. This study strongly suggests Wickerhamia sp. as a promising candidate for bioethanol production from starchy biomass, in particular, PPW through CBP.

Influence of environmental pollution with creosote oil or its vapors on biomass and selected physiological groups of microorganisms

Survival of microorganisms in soils from treatment facility and landfill of wooden railway sleepers contaminated with creosote oil as well as in two types of soils with different content of organic carbon, treated with creosote oil vapors, was assessed. Microbiological assays including determination of: the biomass of living microorganisms method and the number of proteolytic, lipolytic and amylolytic microorganisms were carried out under laboratory conditions. Chromatography analysis of the soil extract from railway sleepers treatment facility was performed using GC/MS. The highest biomass and the number of tested microorganisms were determined in soils from wooden railway sleepers landfill, while the lowest in soil from the railway sleepers treatment facility. Vapors of creosote oil, regardless of the soil type, significantly increased only the number of lipolytic bacteria.

Spring Wheat Cultivation Using a New Bioproduct

&lt;p&gt;Spring wheat is a strategically significant agricultural crop all over the world. Increasing yields of the crop need increasing use of the mineral fertilizers and chemical fungicides – using which becomes less and less popular. They are being substituted with various bioproducts being developed all over the world, including Russia. All-Russian Research Institute of Reclaimed Lands (VNIIMZ) has created a novel bioproduct – LBP – featuring physiologically significant amounts of growth factors and nutritive elements favorable for the plants. This work evaluates an LBP effect on spring wheat, Irgina sort, when using LPB as a supplementary fertilizer with a mineral fertilizer as a basic one. The research was carried out in microplot experiments at a VNIIMZ’s test site, Tver Region, Russian Federation, in 2009-2010. Among all options studied, a 0.1 l/sq.m LBP dose (added by spraying on bushing-out and earing plants) proved to be the most effective. That option yielded 16.31 metric centners/hectare, which is 27.3% higher than the same without LBP is. A grain quality analysis showed the following nutritive value rise compared to references: cellulose, oil and calcium (CaO) increased by 10…12%, 9…10%, and 10…12%, respectively. Soils of the plants treated with LBP generally contained more nitrogen compounds, less amylolytic microorganisms (competing for nitrogen) and Fusarium wilt ones - which totally provided better conditions for the spring wheat growth.&lt;/p&gt;

Variation in biological and physicochemical parameters of the soil affected by uncontrolled landfill sites

Defining the biological and physicochemical parameters in soil under illegally dumping sites provides information on the real threat and the direction of changes in the soil environment. The aim of the study was to investigate the effect of uncontrolled dump sites which differed in the composition of the waste deposited on the development of selected groups of soil microorganisms and the activity of redox enzymes and selected physicochemical soil parameters. Additionally, it was verified whether the biological and physicochemical parameters differ in soil depending on the depth (0–20 and 20–40 cm). The research covered three waste landfill sites (W1, W2, W3), the arable field (A) found in the zone of the effect of the dumping site as well as the control point (C). The microbiological analyses show that most amylolytic microorganisms (87.0 × 105 cfu), celullolytic (46.4 × 105 cfu), proteolytic (148.6 × 105 cfu) and bacteria in total (123.2 × 105 cfu) were isolated from the surface later of control soil (C), and definitely least—from the area of dumping sites W1 and W2. The waste accumulated in W1 and W2 led to the soil depletion in organic matter, inhibited the development of microorganisms and their enzymatic activity. The soil under landfill site W3 showed the highest values recorded for physicochemical properties, the count of Actinobacteria, as well as the activity of dehydrogenases and catalase. The concentration of heavy metals in soil under landfill site W3 was even tenfold higher than the values recorded at the other measurement points, which must have been due to the effect of the type of the waste dumped in landfill site W3, where biodegradable waste of organic origin dominated. Disturbing the biological control and unfavourable changes in the microbiocenotic composition were mostly revealed in soil at landfill site W1.

Direct fermentation of potato starch and potato residues to lactic acid by Geobacillus stearothermophilus under non-sterile conditions.

BACKGROUNDLactic acid is an important biorefinery platform chemical. The use of thermophilic amylolytic microorganisms to produce lactic acid by fermentation constitutes an efficient strategy to reduce operating costs, including raw materials and sterilization costs.RESULTSA process for the thermophilic production of lactic acid by Geobacillus stearothermophilus directly from potato starch was characterized and optimized. Geobacillus stearothermophilus DSM 494 was selected out of 12 strains screened for amylolytic activity and the ability to form lactic acid as the major product of the anaerobic metabolism. In total more than 30 batches at 3–l scale were run at 60 °C under non-sterile conditions. The process developed produced 37 g L−1 optically pure (98%) L-lactic acid in 20 h from 50 g L−1 raw potato starch. As co-metabolites smaller amounts (<7% w/v) of acetate, formate and ethanol were formed. Yields of lactic acid increased from 66% to 81% when potato residues from food processing were used as a starchy substrate in place of raw potato starch.CONCLUSIONSPotato starch and residues were successfully converted to lactic acid by G. stearothermophilus. The process described in this study provides major benefits in industrial applications and for the valorization of starch-rich waste streams. © 2015 The Authors.Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pasting Properties of White Corn Flours of &amp;lt;i&amp;gt;Anoman&amp;lt;/i&amp;gt; 1 and &amp;lt;i&amp;gt;Pulut Harapan&amp;lt;/i&amp;gt; Varieties as Affected by Fementation Process

This research was aimed to evaluate the pasting properties of white corn flour made from Anoman 1 and Pulut Harapan varieties as affected by the fermentation process of the corn grits. The fermentation process studied were 1) spontaneous fermentation (SF); 2) fermentation with the addition of a complete starter culture at 0 hour (CC fermentation) and 3) fermentation of (CC) with additional inoculation of starter culture containing amylolytic microorganisms at 16 hours (AC fermentation). The evaluation of pasting properties was done on the flour made from corn grits fermented for 0, 36, 48, and 72 hours. Our results showed that pasting properties of corn flour of Anoman 1 and Pulut Harapan varieties were affected by fermentation process. Addition of starter culture in the fermentation showed more complex effect on the pasting properties and was a function of the fermentation time. Fermentation process of corn grits affected the pasting properties of the resulted flour, both for Anoman I and Pulut Harapan corn varieties. The differences in the effect of fermentation process on the pasting properties were due to the different amylose/amylopectin content. AC fermentation of corn grits could increase the stability of paste for flour containing higher amylose content but decrease the stability of paste for flour containing high amylopectin. Specifically, CC fermentation caused significant increase in the peak viscosity value especially for corn flour of Pulut Harapan. Fermentation for up to 48 h had resulted in corn flour of Pulut Harapan variety having a higher PV value, but it did not affect the tendency to retrograde.

Engineering Saccharomyces cerevisiae for next generation ethanol production

AbstractConversion of cellulose, hemicellulose or starch to ethanol via a biological route requires enzymatic conversion of these substrates to monosaccharides that can be assimilated by a fermenting organism. Consolidation of these events in a single processing step via a cellulolytic or amylolytic microorganism(s) is a promising approach to low‐cost production of fuels and chemicals. One strategy for developing a microorganism capable of such consolidated bioprocessing (CBP) involves engineering Saccharomyces cerevisiae to expresses a heterologous enzyme system enabling (hemi)cellulose or starch utilization. The fundamental principle behind consolidated bioprocessing as a microbial phenomenon has been established through the successful expression of the major (hemi)cellulolytic and amylolytic activities in S. cerevisiae. Various strains of S. cerevisiae were subsequently enabled to grow on cellobiose, amorphous and crystalline cellulose, xylan and various forms of starch through the combined expression of these activities. Furthermore, host cell engineering and adaptive evolution have yielded strains with higher levels of secreted enzymes and greater resistance to fermentation inhibitors. These breakthroughs bring the application of CBP at commercial scale ever closer. This mini‐review discusses the current status of different aspects related to the engineering of S. cerevisiae for next generation ethanol production. © 2013 Society of Chemical Industry

Amylolytic Microorganism from São Paulo Zoo Composting: Isolation, Identification, and Amylase Production

Composting is a way of transforming the organic waste into fertilizer, minimizing the use of inorganic compounds that may contaminate the environment. This transformation is the result of the microorganism action, converting complex carbon sources into energy. Enzymes that are exported by the microorganisms to the surrounding environment mediate this process. The aiming of the present work is to prospect the compost produced by the organic composting unit (OCU) of the Fundação Parque Zoológico de São Paulo (FPZSP) to find novel starch hydrolyzing organisms (SHO) that secrete large amounts of amylases under harsh conditions, such as high temperature. We found five bacterial isolates that have amylolytic activity induced by soluble starch and 39°C temperature of growth. These bacterial strains were identified by MALDI-TOF (Matrix-assisted laser desorption/ionization-Time of Flight) analysis, a rapid and efficient methodology for microbe identification in large scale. Our results present amylolytic strains that belong to diverse taxonomic groups (Solibacillus silvestris, Arthrobacter arilaitensis, Isoptericola variabilis, and Acinetobacter calcoaceticus); some of them have never been associated with this kind of hydrolytic activity before. The information regarding enzyme induction will be important to optimize the production by the bacterial isolates, which may be a great value for biotechnological applications.

Structural and functional properties of actinomycetal communities in chernozems and saline soils of Ukraine

In the profiles of ordinary and southern chernozems, the total numbers of amylolytic microorganisms and actinomycetes decreased with the depth by 2.4–4.2 and 3.4 times, respectively; in the profiles of solonetz and solonchak soils, by 4.2–5.3 and 4.8 times, respectively. In the genetic horizons of the ordinary and southern chernozems, the share of actinomycetes amounted to 29–30% of the total population of microorganisms; in the saline soils, it increases with the depth from 23 to 43%. In the chernozems, Streptomyces violaceomaculatus (Roseus section), St. sporoherbeus (Azureus), St. aerionidulus (Cinereus), St. enduracidicus (Cinereus), and St. grisinus (Cinereus) predominated; in the saline soils, St. violaceomaculatus and St. aerionidulus prevailed. In the ordinary chernozem, the Berger-Parker index was 1.5 times higher than in the southern chernozem. High similarity was found between the streptomycete communities in the chernozems (the Sorensen coefficient was 0.78). In the solonetzes, the species richness of the streptomycetes was higher by 1.7 times than in the solonchaks. In the chernozems, the similarity of the streptomycete communities was higher than in the solonchaks (0.78 and 0.60, respectively).

Selection of potential microorganism for sago starch fermentation

Fermentation process of sago starch for the production of bioproduct requires potential microorganism that have ability to hydrolyze sago starch. The purpose of this research was to get the potential of amylolytic microorganisms for their capability of amyloglucosidase activity and to know the sugar strains of the fermentation result. Eleven amylolytic microorganisms (9 strains of mold and 2 strains of yeast) were obtained from the collection Research Centre for Biotechnology – Indonesian Institute of Sciences (LIPI), Cibinong-Bogor were used. The selection step was carried out based on their capability of starch hydrolysis to reducing sugar. The best result indicates that the production of reducing sugar reached the highest 18.485 ppm and amyloglucosidase activities was 3.583 units by KTU-1 strain. The highest total acid obtained was 5.85 mg/mL by Rhizopus IFO.R5442. The cell biomass was obtained between 0.5 to 1.74 g dry weight/100 mL and pH of the final fermentation (72 h) were 3.57 to 8.38.© 2006 Jurusan Biologi FMIPA UNS SurakartaKey words: sago starch, fermentation, potential microorganism, bioproduct.

Occurrence of amylolytic microorganisms in soil depending on the type of cultivation

The count and growth dynamics of amylolytic microorganisms in soil beyond rhizosphere and within rhizosphere as well as in potato rhizoplane was compared in ecological (organic) and conventional farming systems. Potatoes in the ecological system were fertilized only with organic fertilizers and in the conventional system NPK fertilizers + manure were used. The results showed that the count of bacteria showing amylolytic activity was generally higher in ecological farming than in conventional one. Vegetation stage had a significant effect on the growth dynamics of microorganisms tested. The highest level of their count was achieved at the end of the vegetation during tuber harvest maturity. A remarkable smaller count of microorganisms secreting amylases was recorded in the soil beyond rhizosphere in comparison with the rhizosphere area and rhizoplane. Selected physico-chemical properties of soils (humidity and pH) were more favourable in the soil cultivated under organic farming system in comparison to the conventional one.