Kinetics of the utilization of different C sources and the cellulose formation by Acetobacter xylinum

Different methylated glucose derivatives and cellobiose were examined as the carbon sources for growth and cellulose formation by Acetobacter xylinum. HPLC studies were carried out to gain information about the kinetics of the utilization of the C sources used. The type and yields of the synthesized cellulose were described. Besides glucose, cellobiose was a substrate for the synthesis of this polysaccharide by the bacteria. Other methylated derivatives of glucose were not accepted for a comparable synthesis of this polymer. An estimation of citrate in an unmodified culture liquid (SH medium) showed utilization in a late phase of cultivation. The influence of this organic acid on the pH value, cellulose synthesis and growth is described. By the application of citric acid as a sole carbon source “gel-like” forms of cellulose were formed generally.     

Production of bacterial cellulose from <Emphasis Type="Italic">Enterobacter amnigenus</Emphasis> GH-1 isolated from rotten apple

Bacterial cellulose finds novel applications in biomedical, biosensor, food, textile and other industries. The optimum fermentation conditions for the production of cellulose by newly isolated Enterobacter amnigenus GH-1 were investigated. The strain was able to produce cellulose at temperature 25–35°C with a maximum at 28°C. Cellulose production occurred at pH 4.0–7.0 with a maximum at 6.5. After 14 days of incubation, the strain produced 2.5 g cellulose/l in standard medium whereas cellulose yield in the improved medium was found to be 4.1 g/l. The improved medium consisted of 4% (w/v) fructose, 0.6% (w/v) casein hydrolysate, 0.5% (w/v) yeast extract, 0.4% (w/v) disodium phosphate, and 0.115% (w/v) citrate. Addition of metal ions like zinc, magnesium, and calcium and solvents like methanol and ethanol were found to be stimulatory for cellulose production by the strain. The strain used natural carbon sources like molasses, starch hydrolysate, sugar cane juice, coconut water, coconut milk, pineapple juice, orange juice, and pomegranate juice for growth and cellulose production. Fruit juices can play important role in commercial exploitation of bacterial cellulose by lowering the cost of the production medium.     

Comparisons of physical properties of bacterial celluloses produced in different culture conditions using saccharified food wastes

The saccharogenic liquid (SFW) obtained by the enzymatic saccharification of food wastes was used as a medium for production of bacterial cellulose (BC). The enzymatic saccharification of food wastes was carried out by the cultivation supernatant ofTrichoderma harziaum FJ1 culture.Acetobacter xylinum KJ1 was employed for the BC production culture. The physical properties, such as polymerization, crystallinity, Young's modulus, and tensile strength, of BCs produced by three culture methods: the static cultures using HS (Hestrin-Schramm) as a reference medium (A) or the SFW medium (B), the shaking culture (C) or the air circulation culture (D) using the SFW medium, were investigated. The degrees of polymerization of BCs produced under the different culture conditions (A∼D) showed 11000, 9500, 8500, and 9200, respectively. Young's modulus was 4.15, 5.0, 4.0, and 4.6 GPa, respectively. Tensile strength was 124, 200, 80, and 184 MPa, respectively. All of the BC had a form of cellulose I representing pure cellulose. In the case of the shaking culture, the degree of crystallinity was 51.2%, the lowest degree. Under the other culturing conditions, the trend should remain in the range of 89.7–84%. Overall, the physical properties of BC produced from SFW were similar to those of BC from HS medium, a commercial complex medium, and BC production by the air circulation culture mode brought more favorable results in terms of the physical properties and its ease of scale-up. Therefore, it is expected that a new BC production method, like air circulation culture using SFW, would contribute greatly to BC-related manufacturing.     

Production of bacterial cellulose from Komagataeibacter saccharivorans strain BC1 isolated from rotten green grapes

Abstract

Bacterial cellulose (BC) is one of the prominent biopolymers that has been acquiring attention currently due to its distinctive properties and applications in various fields. The current work presents the isolation of Komagataeibacter saccharivorans strain BC1 isolated from rotten green grapes, followed by biochemical and genotypic characterization, which confirmed that the strain is capable of synthesizing cellulose. Further, production media was designed and certain variables such as carbon, nitrogen sources, pH, and temperature were optimized in order to obtain the maximum concentration of cellulose production. We found mannitol to be the ideal carbon source and yeast extract as the ideal nitrogen source with a highest BC dry yield of 1.81?±?0.25?g/100?mL at pH 5.76 for a week at 30?°C.The charcterization of pellicles by FTIR spectrum depicted similar functional groups present in synthesized BC as that of the commercial cellulose. X-ray diffraction revealed that BC showed 82% crystallinity. Surface morphology of the dried pellicle was studied by SEM image which showed that the BC surface was tightly packed with thin fibers with less porosity. Hence the study demonstrates that the isolates of K.saccharivorans could be used to produce a biopolymer in a short period of time using a modified production medium.     

Production and Characterization of an Exopolysaccharide by Yeast

Antarctic yeast strains were investigated for exopolysaccharide biosynthesis and the Sporobolomyces salmonicolor AL₁ strain was selected. It was studied for exopolysaccharide biosynthesis on different carbon and nitrogen sources. The investigations showed that sucrose and ammonium sulphate were suitable culture medium components for polymer biosynthesis. Exopolysaccharide formation by the yeast strain was accompanied by a decrease in the culture medium pH value from the initial pH 5.3 to pH 1.7–2.0. During the biosynthetic process, the dynamic viscosity of the culture broth increased to the maximum value of 15.37 mPas and the polysaccharide yield reached 5.63 g/l on a culture medium containing 5.00% sucrose and 0.25% ammonium sulphate at a temperature of 22 °C for 120 h. The crude polysaccharide obtained from Sp. salmonicolor AL₁ featured high purity (90.16% of carbon content) and consisted of glucose (54.1%), mannose (42.6%) and fucose (3.3%). Pure mannan containing 98.6% of mannose was isolated from it.     

Utilization of -xylose as carbon source for production of bacterial cellulose

Utilization of -xylose as carbon source for production of bacterial cellulose was studied. Seventeen strains of acetic acid bacteria were screened for their cellulose productivity in -glucose, -xylose, and -xylose/ -xylulose mixed media, respectively. -Xylose was not well metabolized by any bacterial strains that exhibited high cellulose production in -glucose medium. Consequently, bacterial cellulose production in -xylose medium was unsuccessful. -Xylose, however, became utilizable substrate for bacterial strains if xylose-isomerase was added to the medium. Acetobacter xylinus IFO 15606 was the best cellulose producer in -xylose/ -xylulose mixed medium, so cultural conditions were studied for enhanced cellulose production. With pH controlled, the strain could produce cellulose at a yield exceeding 0.3 g per 100 ml of -xylose/ -xylulose mixed medium, which was comparable to the yields in -glucose medium by excellent producers in the literature.     

Comparison of productivity and quality of bacterial nanocellulose synthesized using culture media based on seven sugars from biomass

Komagataeibacter xylinus ATCC 23770 was statically cultivated in eight culture media based on different carbon sources, viz. seven biomass-derived sugars and one sugar mixture. The productivity and quality of the bacterial nanocellulose (BNC) produced in the different media were compared. Highest volumetric productivity, yield on consumed sugar, viscometric degree of polymerization (DP_v, 4350–4400) and thermal stability were achieved using media based on glucose or maltose. Growth in media based on xylose, mannose or galactose resulted in lower volumetric productivity and DP_v, but in larger fibril diameter and higher crystallinity (76–78%). Growth in medium based on a synthetic sugar mixture resembling the composition of a lignocellulosic hydrolysate promoted BNC productivity and yield, but decreased fibril diameter, DP_v, crystallinity and thermal stability. This work shows that volumetric productivity, yield and properties of BNC are highly affected by the carbon source, and indicates how industrially relevant sugar mixtures would affect these characteristics.     

Cellulose synthesized by Acetobacter xylinum in the presence of multi-walled carbon nanotubes

The structure of bacterial cellulose is affected by the bacterial strain used, culture media and cultivation conditions. In this study, acid-treated multi-walled carbon nanotubes (MWNTs) were added into a static culture medium and their effect on bacterial cellulose structure was studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), CP/MAS (13)C NMR and X-ray diffractometry. The bacterial cellulose ribbons and the MWNTs interwound and formed a three-dimensional network architecture. Band-like assemblies with sharp bends and rigidity were also produced in the presence of MWNTs. The intermolecular hydrogen bonds in bacterial cellulose produced in the presence of MWNTs were weakened. The crystal structure, cellulose I(alpha) content, crystallinity index (CrI) and crystallite size all changed. The results may suggest that the acid-treated MWNTs containing hydroxyl groups interact with the sub-elementary bacterial cellulose fibrils, subsequently interfering with the aggregation and crystallization.     

Cellulolytic Actitivity of Penicillium digitatum and P. italicum Related to Fungal Growth and to Pathogenesis in Citrus Fruits

Cultural conditions under which Penicillium digitatum and P. italicum develop were an important factor in determining the extent of their cellulolytic activity. At pH 5.5–7.5 of the culture medium, Cx-cellulase activity was correlated with mycelial dry weight. However, at pH 4.5 and more so at pH 3.5, activity was markedly reduced while fungal growth was not affected. Cx-cellulases of both species were not induced by the presence of carboxymethyl cellulose as a carbon source and were defined as constituent enzymes. Cellulase activity of the two Penicillia on different carbon sources was detected prior to the initiation of sporulation. A sporeless mutant of P. digitatum exhibited cellulolytic activity similar to that of the normal strain, suggesting no role for sporulation in the Cx-cellulase synthesis. Cx-cellulase activity in Valencia oranges started during the early stages of pathogenesis, before the appearance of disease symptoms. Correlation between the cellulase activity and the severity of the disease symptoms was apparent during the first three days after inoculation. At the end of the incubation period both fungi almost reached their maximum enzymatic activity, whereas the disease index continued to rise gradually until total fruit rot was achieved. A possible role of Cx-cellulases of the two Penicillia in the early stages of pathogenesis was suggested.     

Production of Cellulase(s) byMyricoccum albomyces

The ability ofMyricoccum albomyces to produce extracellular cellulase(s) has been studied in a stationary liquid medium. Different cellulosic carbon sources were used. The organism was able to produce cellulose 1,4-β-cellobiosidase (C₁) and cellulase (C_x) activities. The optimum temperature for C₁ and C_x activity was 45 °C. The optimum pH for C₁ activity was pH 6 while that for C_x was pH 5.     

Influence of the mycelium growth conditions on the production of amylolytic,proteolytic and pectinolytic enzymes by Aspergillus niger C

Various nitrogen and carbon sources, as well as natural products, were examined as inducers of the production of amylases, proteases and pectinases by A. niger C. A. niger C grown on wheat bran extract medium provided culture supernatants with the highest enzymatic activities. Some culture conditions, e.g. pH, medium temperature and time period of cultivation, were optimalized to improve the growth and enzymes biosynthesis by A. niger C.     

Production of cellulose from glucose by Acetobacter xylinum

Acetobacter xylinum 1FO 13693 was selected as the best cellulose-producing bacterium among 41 strains belonging to the genus Acetobacter and Agrobacterium. Cellulose was found to be produced at the liquid surface in static liquid cultivation. The rate of cellulose production depended proportionally on the surface-area of the culture medium and was unaffected by the depth and volume of the medium. The optimum pH for cellulose production was 4.0 to 6.0. Glucose, fructose and glycerol were preferred carbon sources for cellulose production. The yield of cellulose, relative to the glucose consumed, decreased with an increase in initial glucose concentration, and gluconic acid accumulated at a high initial glucose concentration. The decrease in cellulose yield could be due to some glucose being metabolized to gluconic acid. However, the accumulated gluconic acid did not affect cellulose production. The culture conditions of the bacterium for cellulose production were optimized. The maximum production rate of cellulose was 36 g/d·m², with a yield of 100% for added glucose under the optimal conditions.     

Enhanced production of cellulases byCellulomonas strains grown on different cellulosic residues

Cellulomonas strains consumed commercial cellulose, cellulosic residues, xylan, cellobiose and carboxymethyl cellulose (CMC) as carbon sources in liquid culture, the growth being the most on cellobiose medium. All three components of the cellulase complex ofCellulomonas were produced when the organisms utilized all substrates as sole carbon and energy sources. The filter-paper cellulase (FPase) and endo-glucanase (CMCase) activities were higher in media containing α-cellulose and cellulosic residues than in media containing CMC, cellobiose, and xylan. Cell-free supernatants of all organisms exhibited greater CMC hydrolyzing activity than filter paper and β-glucoside hydrolyzing activities. All strains synthesized β-glucosidase maximally on cellobiose followed by commercial cellulose and cellulosic residues.C. biazotea produced the highest FPase and CMCase activity during growth on α-cellulose. It was followed byC. flavigena, C. cellasea, andC. fimi. Endo-glucanase and FPase from all organisms were secreted into the medium; 10–13 % became adsorbed on the surface of the insoluble substrates and could be successfully eluted using Tween 80. β-Glucosidase was located in cell extracts from all organisms.C. biazotea produced FPase and β-glucosidase activities several-fold greater than those produced by many other strains ofCellulomonas and some other cellulolytic bacteria and fungi. These studies were supported byPakistan Atomic Energy Commission. Some chemicals were purchased from funds allocated byUnited States Agency for International Development, Washington (DC, USA), under PSTC proposal 6.163.     

Microbial degradation of cyanide and thiocyanate

The role played by a bacterial community composed ofPseudomonas putida, strain 21;Pseudomonas stutzeri, strain 18; andPseudomonas sp., strain 5, and by physical and chemical factors in the degradation of CN⁻ and SCN⁻ was studied. It was shown that the degradation of CN⁻ is determined both by the action of bacteria and by abiotic physical and chemical factors (pH, O₂, temperature, the medium agitation rate, etc.). The contribution of chemical degradation was found to increase drastically at pH below 9.0; when air was blown through the medium (irrespective of the pH value); under active agitation of the medium; and when the medium surface interfacing air was increased. Even at elevated pH values (9.0-9.2), suboptimal for bacterial growth, the microbial degradation could account for at most 20–25 mg/1 of CN⁻, regardless of its initial concentration. When CN⁻ and SCN⁻ were concurrently present in the medium, the former compound was the first to be degraded by microorganisms. The rate of bacterial degradation of SCN⁻ under continuous cultivation in a chain of reactors was found to depend on its concentration, the medium flow rate, agitation rate, and the pattern of carbon source supply and could exceed 1 g/(l day). CN⁻ and SCN⁻ are utilized by bacteria solely as nitrogen sources. The mechanism of CN⁻ and SCN⁻ degradation by the microbial community is discussed. Deceased.     

Growth of Paramecium tetraurelia in Bacterized,Monoxenic Cultures1

Wild type and mutant Paramecium tetraurelia were grown in monoxenic cultures by first growing Enterobacter aerogenes on a defined medium and then adding the Paramecium to the stationary phase bacterial culture. The bacterial growth was proportional to the concentration of the carbon source (citrate), and the Paramecium growth was dependent upon both the bacterial density and the starting density of Paramecium. The behavior, electrophysiological properties, ciliary lipid composition, and growth characteristics were similar to the commonly used bacterized medium (Cerophyl) except that 5–10 times greater Paramecium yields were reliably obtained.     

Cellulose production from<Emphasis Type="Italic">Gluconobacter oxydans</Emphasis> TQ-B2

Gluconobacter oxydans that produces the cellulose was isolated. In order to confirm the chemical features of cellulose, various spectrophtometeric analysis were carried out using electron microscopy, X-ray diffractogram, and CP/MAS¹³C NMR. The purified cellulose was found to be identical to that ofAcetobacter xylinum. For effective production of cellulose, the various carbon and nitrogen sources, mixture of calcium and magnesium ions, and biotin concentration were investigated in flask cultures. Among the various carbon sources, glucose and sucrose were found to be best for the production of cellulose, with maximum concentration of 2.41 g/L obtained when a mixture of 10 g/L of each glucose and sucrose were used. With regard to the nitrogen sources, when 20 g/L of yeast extract was used, the maximum concentration of bacterial cellulose was reached. The concentration of cellulose was increased with mixture of 2 mM of each Ca²⁺ and Mg²⁺. The optimum biotin concentration for the production of cellulose was in the range of 15 to 20 mg/L. At higher biotin concentration (25–35 mg/L), the bacterial cellulose production was lower.     

Impact of carbon sources on growth and oxalate synthesis by the phytopathogenic fungus <Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis>

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic potential, were dissimilar when the organism was grown in the presence of different carbon sources. The highest oxalate-to-biomass ratios were observed with pyruvate, formate, malate, acetate, and succinate. Time-course studies with acetate-supplemented cultures revealed that acetate and glucose consumption by S. sclerotiorum D-E7 coincided with oxalogenesis and culture acidification. By day 5 of incubation, oxalogenesis was halted when cultures reached a pH of 3 and were devoid of acetate. In succinate-supplemented cultures, oxalogenesis essentially paralleled glucose and succinate utilization over the 9-day incubation period; during this time period, culture pH declined but never fell below 4. Overall, these results indicate that carbon sources can regulate the accumulation of oxalate, a key pathogenicity determinant for S. sclerotiorum.     

Cellulase production on glucose-based media by the UV-irradiated mutants of Trichoderma reesei

From 22,791 mutants of a cellulase hyper-producing strain of Trichoderma reesei (Hypocrea jecorina), ATCC66589, as the parent, we selected two mutants, M2-1 and M3-1, that produce cellulases in media containing both cellulose and glucose. The mutation enabled the mutants to produce cellulases, which were measured as p-nitrophenyl β-d-lactopyranoside-hydrolyzing activities, in media with glucose as a sole carbon source, although M2-1 exhibited different sensitivities to glucose from M3-1. When the mutants were grown for 8 days on a medium with cellulose as a sole carbon source, the filter-paper-degrading activities (FPAs) per gram of cellulose were 257 and 281 U for M2-1 and M3-1, respectively, values that were 1.1–1.2 times higher than that of the parental strain. Cellulase production by M2-1 and M3-1 on a medium with a continuously fed mixture of glucose and cellobiose resulted in 214 and 210 U of FPA/gram carbon sources, respectively, whereas less efficient production (140 U of FPA/gram carbon source) was achieved by the parental strain. The improved cellulase productivity of the mutants allows us to use glucose as a carbon source for efficient on-site production of cellulases with quality/quantity-controlled feeding of soluble carbon sources and inducers.     

基于梯度稀释法分析细菌多样性对土壤碳代谢的影响

为探究土壤微生物多样性对土壤碳代谢过程的影响,利用梯度稀释法(处理D1、D3和D5分别为稀释10-1、10-3和10-5倍)改变土壤样品中原始土壤微生物群落的多样性,以探究土壤微生物群落多样性减少对土壤碳代谢的影响。进行为期6周的预培养实验,以消除梯度稀释法对土壤样品中微生物群落丰度的影响,并通过Q-PCR和高通量测序测定预培养结束后3种土壤样品中细菌丰度及其基因多样性指数(ACE、Chao1、Shannon),以验证预培养实验结果。后加入等量葡萄糖(0.5g/100g干土)继续培养,并于培养期间测定3种处理土壤的碳矿化速率,进行biolog ECO板实验,分析计算各土壤样品中细菌的功能多样性指数(Shannon指数(H)、Simpson指数(D)、McIntosh指数(U))及碳源代谢强度。结果表明:(1)3种处理土壤样品碳矿化速率及累积碳矿化量大小排序为:D1> D3> D5,且D1与D3、D5处理均有显著差异(P<0.05)。(2)D1处理下土壤样品中微生物群落的孔平均颜色变化率(AWCD)、功能多样性指数(Shannon指数(H)、McIntosh指数(U))均显著高于D3、D5处理(P<0.05)。(3)对31种碳源吸光度做主成分分析(PCA)分析,发现3种稀释处理下土壤样品的碳源利用模式存在差异,且D1处理下的土壤微生物群落对碳源的代谢功能大于D3、D5处理。因此,该研究表明土壤微生物多样性的减少会降低土壤的碳矿化速率及其碳源代谢强度,对土壤碳代谢过程产生一定程度的不利影响。     

Statistical optimization of bacterial cellulose production by Leifsonia soli and its physico-chemical characterization

Bacterial cellulose has multiple applications in various industries such as food, biomedical, textile due to its uniqueness of being a better bio-compatible coating agent, binding material, etc. In this study, optimization of the culture medium for producing BC from Leifsonia soli was carried out by selecting different parameters. Five significant factors such as maltose, pH, incubation days, soy whey and calcium chloride were estimated through ANOVA based response surface methodology. Maximum cellulose production (5.97 g/L) was obtained where maltose 1 % (w/v) supplemented with 0.8 % (v/v) soy whey and calcium chloride 0.8 % (w/v) at pH 6.5 for 7 days of incubation. In addition, assurance of cellulose production from bacteria was done by using High-performance liquid chromatography analysis. Further, the structure and purity of obtained cellulose were examined by SEM and elemental analysis where it was observed that the sample holds the value of carbon 44.1 ± 0.20 % and hydrogen 6.2 ± 0.3 %, respectively. This study concludes that the addition of maltose and soy whey could be used as carbon, nitrogen sources and calcium chloride was used as an additive for the bacterial cellulose production compared to the Hestrin Schramm medium. In addition, the calculated water holding capacity of the sample was found to be 73 %.