亚麻脱胶菌种的选育及脱胶过程的初步研究

从沤麻主生物期的水中分离产果胶酶的菌株经初筛、复筛获得了三株专性厌氧细菌,初步鉴定为费氏芽孢杆菌,对其亚麻脱胶性能进行了初步研究,确定人工加菌沤麻的最适工艺条件为：加菌量2％,加菌时间：沤麻进入主生物期零时,菌株A优于其它菌株．结果表明：采用上述工艺进行沤麻实验,可缩短沤麻时间30％,并可提高麻纤维质量。     

亚麻微生物脱胶优势菌的选育及其应用

从亚麻种植土壤与沤麻水中分离出96株能分解果胶的菌株。通过初筛和复筛获得4株果胶酶高产菌株。其中,在果胶平板培养基上生长速度快、产果胶酶活力高的12号菌株被确定为优势菌,经鉴定其为枯草芽孢杆菌。最适脱胶条件为：麻水比1：15,pH7．5,温度32～33℃,预培养的优势菌接种量3％。结果表明,采用优势菌的脱胶周期比对照缩短50％左右,而且麻的纤维质量明显得以改善。     

葡萄糖醛酸木聚糖酶在枯草芽孢杆菌中的表达及发酵条件优化

为了研究葡萄糖醛酸木聚糖酶在枯草芽孢杆菌中异源表达,笔者从枯草芽孢杆菌中克隆得到带有自身信号肽的葡萄糖醛酸木聚糖酶基因,将其构建到大肠杆菌-枯草芽孢杆菌穿梭质粒中,转化入枯草芽孢杆菌WB800,得到重组菌。通过发酵条件以及培养基成分优化,重组菌中葡萄糖醛酸木聚糖酶酶活达到76.0 U/mL,约为优化前产酶量的5.4倍。葡萄糖醛酸木聚糖酶在枯草芽孢杆菌中实现高效异源表达,为其进一步的实际应用奠定了基础。     

适于罗布麻生物脱胶的果胶酶产生菌分离筛选与表征

在青海柴达木盆地沤制的罗布麻表皮中分离得到两株适于罗布麻脱胶的高产果胶酶菌株,经形态、生理生化指标鉴证和16SrDNA菌种鉴定,确定一株为新的果胶酶产生菌琼氏不动杆菌（Acinetobacter junii）,一株为枯草芽孢杆菌（Bacillus subtilis）。水解圈实验得出前者H／C值（H／C为水解圈直径H与菌落直径C之比）为5,后者为3;经酶活力测定,在37℃下,琼氏不动杆菌（Acinetobacter junii）在11h达到产酶高峰（酶活力为103．2IU／mL）,枯草芽孢杆菌（Bacillus subtilis）培养至9h达到产酶高峰（酶活力为91．6IU／mL）,但前者最高酶活力比后者高12．5％;经脱胶实验得出两菌残胶率分别为18．47％和17．31％,对罗布麻生物脱胶有较好的适用性。     

极端耐热木聚糖酶基因在枯草芽孢杆菌中的整合表达

目的:为了在枯草芽孢杆菌中整合表达极端耐热木聚糖酶。方法:将嗜热网球菌(Dictyoglomus thermophilum)Rt46B.1的极端耐热木聚糖酶基因xynB通过穿梭载体pDL整合到B.subtilis168染色体上,使其实现表达。结果:极端耐热木聚糖基因在枯草芽孢杆菌中成功整合并表达。结论:基因工程菌B.subtilis168-xynB能外泌表达极端耐热木聚糖酶,且表达水平为0.732IU/mL,比在大肠杆菌中的高。酶学性质表明,此酶分子量约为24kD,其最适反应温度为85℃,最适反应pH值为6.5,且在弱碱性条件下稳定。     

分解玉米赤霉烯酮菌株的分离、鉴定及其产酶特征

【目的】从发酵食品材料中筛选出对玉米赤霉烯酮(ZEN)有分解作用的微生物,研究其分解效率及产酶特征并进行菌种鉴定。【方法】利用添加ZEN毒素类似物(PL)的固体培养基对25种发酵食品材料进行初筛,获得毒素类似物耐受菌株,经过用ZEN复筛,得到高效分解ZEN的细菌。用高效液相色谱法(HPLC)分析培养物残留ZEN,评价菌株对ZEN的分解效率。初步分析该菌株产纤维素酶、木聚糖酶及β-葡萄糖苷酶的特性。通过微生物形态学、分子生物学方法进行菌种鉴定,确定该菌的系统分类学地位。【结果】从发酵食品材料中筛选出一株分解ZEN的菌株BF-B-3,经初步鉴定该菌株为枯草芽孢杆菌(Bacillus subtilis)。其ZEN分解率达62.48%,测定该菌产纤维素酶、木聚糖酶及β-葡萄糖苷酶活力分别为160.38、84.51和4.14 U/mL。【结论】枯草芽孢杆菌属于饲用微生物,生物安全性高,所分离到的枯草芽孢杆菌疑似株(Bacillus subtilis)BF-B-3菌株,可作为具有分解ZEN功能的益生菌使用,具有较好的应用前景。     

亚麻纤维脱胶菌的筛选及脱胶效果研究

为筛选亚麻纤维脱胶菌株,从麻脱胶废水、废麻堆积物等7个含麻胶质样品中分离得到39株能分解果胶的菌株.采用水解圈法复筛选出8株果胶酶活性较高的菌株,经果胶酶、纤维素酶活性测定和菌体脱胶试验,最终确定8-1是优良的亚麻脱胶菌株,该菌株果胶酶活可达663.17 u/mL,而纤维素酶活仅为9.13 u/mL.菌株8-1经形态观察、Biolog菌种鉴定系统鉴定以及基于16S rDNA序列构建的系统进化树分析为一株芽孢杆菌.     

“黑老虎”晾晒烟叶表面产酶细菌的鉴定及其在烟草加工上的应用

从江西"黑老虎"晾晒烟叶表面分离筛选出具备产木聚糖酶、果胶酶、纤维素酶、蛋白酶和淀粉酶能力的细菌,并将这些菌株添加到烟丝上进行陈化。结果表明:菌株促进了烟丝的陈化过程,主要体现在香气更加充实、杂气减少、刺激性减弱、余味更净,同时产生香味物质,减少有害物质的含量。其中两株菌经过生理生化实验和16S rDNA鉴定,判定为短小芽孢杆菌和解淀粉芽孢杆菌,此外对这两株菌的培养条件进行了初步优化。从烟叶表面分离筛选的产酶微生物在烟叶陈化过程起重要作用,可制备成微生物菌剂加速烟叶陈化并实现提质增香的效果。本研究以江西"黑老虎"烟叶作为研究对象,根据鉴定平板的水解圈分离筛选具有产木聚糖酶、果胶酶、纤维素酶、蛋白酶、淀粉酶能力的细菌,对陈化结果进行感官评价后发现所筛选的3株产酶细菌(82#,83#和85#)均能有效提升烟丝的品质,主要体现在香气更加充实、杂气减少、刺激性减弱、余味更净。结合形态学观察、理化试验及16S rDNA序列分析,确定3株潜在的提质增香菌均为芽孢杆菌。其中83#为短小芽孢杆菌Bacillus pumilus,而85#为解淀粉芽孢杆菌Bacillus amyloliquefaciens。研究结果表明筛选得到的菌株83#和85#具有作为提质增香菌剂的应用潜力,并为芽孢杆菌应用于烟叶陈化提供理论依据。     

Enhanced co-production of pectinase,cellulase and xylanase enzymes from Bacillus subtilis ABDR01 upon ultrasonic irradiation

The effect of low-intensity ultrasound irradiation was studied to improve the co-production for pectinase, cellulase, and xylanase enzymes using Bacillus subtilis ABDR01. Different parameters such as ultrasonic irradiation at the different growth phases of the bacterial strain, ultrasound power, irradiation duration, and irradiation duty cycle were assessed. Sonication with 90 W ultrasound power, 25 kHz frequency with 70 % duty cycle for 5 min at 6 h of bacterial growth phase gave the maximum productions of 87.82 U/ mL pectinase 22.17 U/ mL cellulase and 137.95 U/ mL xylanase respectively. The enzyme activity of pectinase, cellulase, and xylanase was enhanced by about 38.15 %, 53.77 %, and 24.59 %, respectively, compared to non-sonicated control cultivation. This optimized low-frequency ultrasound irradiation to bacterial cells enhanced the nutrient uptake rate and increased the cell wall permeability, which results in higher enzyme productivity. Our results signify the effectiveness of low-frequency ultrasound irradiation for improved enzyme yields and hyperactivation during microbial fermentation.     

Assessment of Keratinase and Other Hydrolytic Enzymes in Thermophilic Bacteria Isolated from Geothermal Areas in Patagonia Argentina

Thermophilic aerobic bacteria were isolated from two geothermal areas in Neuquén province using two different enrichment methods and a total of 30 isolates were obtained. From chicken feather enrichment cultures, strains affiliated to Bacillus cytotoxicus and Bacillus licheniformis were isolated and all of them demonstrated the capability to degrade completely chicken feather. A preliminary research on biotechnological enzymes' potential demonstrated that all the isolates displayed at least one of the extracellular hydrolytic enzymes tested. Most of the isolates showed protease, inulinase and/or pectinase activities, while cellulase and xylanase activities were less common. In light of these findings, geothermal areas of Argentina may be considered as a potential source of thermophilic bacteria able to produce many industrially relevant enzymes.     

Characterization of endophytic bacteria associated with rose plant (Rosa damascena trigintipeta) during flowering stage and their plant growth promoting traits

Little is known about the bacterial communities associated with the rose plants inhabiting dry desert ecosystems. The aim of this study was to isolate and characterize endophytic bacteria from different organs of rose plant. Endophytic bacteria were observed in healthy roots, stems, leaves, and flowers of rose plant, with a significantly higher density in roots, followed by stems, leaves, and petals. A total of 38 bacterial endophytes were isolated and are closely related phylogenetically to Acetobacter, Acinetobacter, Methylococcus, Bacillus, Micrococcus, Planococcus by 16S rRNA sequence analysis. Six endophytic bacteria were found to produce IAA, solubilize Ca₃(PO₄)₂ and produce siderophore. The six endophytic bacteria all had the capacity to produce hydrolytic enzyme such as cellulase, xylanase, pectinase, amylase, protease, lipase, and chitinase, but difference existed among these isolates.     

Production of thermostable pectinase and xylanase for their potential application in bleaching of kraft pulp

A very high level of alkalophilic and thermostable pectinase and xylanase has been produced from newly isolated strains of Bacillus subtilis and Bacillus pumilus respectively. Enzyme production for pectinase was carried out under SSF using combinations of cheap agricultural residues while xylanase was produced under submerged fermentation using wheat bran as substrate to minimize the cost of production of these enzymes Among the various substrates tested, the highest yield of pectinase production was observed by using combination of WB + CW (6592 U/g of dry substrate) supplemented with 4% yeast extract when incubated at 37 °C for 72 h using deionized water of pH 7.0 as moistening agent. The biobleaching effect of these cellulase free enzymes on kraft pulp was determined. Both xylanase and pectinase showed stability over a broad range of pH from 6 to 10 and temperature from 55 to 70 °C. The bleaching efficiency of the pectinase and xylanase on kraft pulp was maximum after 150 min at 60 °C using enzyme dosage of 5 IU/ml of each enzyme at 10% pulp consistency with about 16% reduction in kappa number and 84% reduction in permanganate number. Enzyme treated pulp when subjected to CDED₁D₂ steps, 25% reduction in chlorine consumption and upto 19% reduction in consumption of chlorine dioxide was observed for obtaining the same %ISO brightness. Also an increase of 22 and 84% in whiteness and fluorescence respectively and a decrease of approximately 19% in the yellowness of the biotreated pulp were observed by pretreatment of the pulp with our enzymatic mixture.     

Isolation and identification of moderately halophilic bacteria producing hydrolytic enzymes from the largest hypersaline playa in Iran

Iran has many hypersaline environments, both the permanent and seasonal ones. One of the seasonal hypersaline lakes in the central desert zone is Aran-Bidgol Lake in which microbial diversity has not been characterized, thus the potential usage of this microbial community in biotechnology remained unknown. In this study, screening the halophilic hydrolytic enzyme-producing bacteria from different areas of this lake led to isolation of 61 gram-positive and 22 gram-negative moderately halophilic bacteria. These bacterial isolates were shown to produce a wide variety of hydrolytic enzymes including DNase, inulinase, amylase, lipase, pectinase, protease, chitinase, pullulanase, cellulase, and xylanase. The most common enzymes were DNase and inulinase in gram-positive bacteria, lipase in gram-negative bacteria, and pullulanase and cellulase in gram-positive cocci. Interestingly, combined hydrolytic activates were observed in some isolates. According to their phenotypic characteristics and comparative partial 16S rRNA sequence analysis, the moderately halophilic strains belonged to the genera Halobacillus, Thalassobacillus, Bacillus, Salinicoccus, Idiomarina, Salicola, and Halomonas.     

Studies on the microbiology of cassava retting for foo-foo production

O kafor N. I jioma B. O yolu , C. 1984. Studies on the microbiology of cassava retting for foo-foo production. Journal of Applied Bacteriology 56 , 1–13.
Five bacteria ( Bacillus, Lactobacillus, Klebsiella, Leuconostoc, and Corynebacterium ) and a yeast ( Candida spp.) were isolated from cassava being fermented for foo-foo production. Retting of cassava was assessed by determining the weight required to crush cylindrical cassava pieces. A weight in excess of 2.5 kg was required to crush an unfermented peeled cassava cylinder 4 mm diameter and 4 cm long whereas a weight as small as 20 g could crush the same piece after retting. The organisms were studied for their ability to cause retting of sterile cassava pieces, alone or in various combinations. Retting did not occur unless either the Bacillus sp. or the Corynebacterium sp. was present. Only these two organisms hydrolysed starch. The lactic acid bacteria lowered the pH of the fermenting medium although they did not bring about retting. The typical aroma of foo-foo was produced, however, only when the lactic acid bacteria were present in the mixture. Only the Corynebacterium sp., was, however, shown to produce pectinolytic enzymes and it is possible that the Bacillus sp. caused retting by disintegrating other cell components. The typical aroma of foo-foo is disliked by some individuals and it seems possible that foo-foo with a bland aroma, which will presumably be more acceptable to this group, can be produced by using organisms causing retting while excluding those forming lactic acid.     

Phenolic constituents in flax bast tissue and inhibition of cellulase and pectinase

Flax bast tissue was sequentially extracted using hexane, propanol, methanol and water as solvents and extracts were analyzed using reverse phase HPLC and ¹³C NMR. Results indicated a large variety of aromatic constituents including flavonoids and hydroxy-methoxy cinnamic acids linked to oligosaccharides and hydroxy acids through glycosidic linkages. The extracts inhibited cellulase and pectinase activities and can thus influence retting.     

A new role for veratryl alcohol: regulation of synthesis of lignocellulose-degrading enzymes in the ligninolytic ascomyceteous fungus, Botryosphaeria sp.; influence of carbon source

A new physiological role for veratryl alcohol in fungi important in the biodegradation of the lignified plant cell wall is presented. Botryosphaeria sp., grown on starch, pectin, cellulose or xylan produced amylase, pectinase, cellulase, xylanase and laccase, whereas glucose and xylose repressed the synthesis of cellulase and xylanase, but not laccase. When cultured on each of these substrates in the presence of veratryl alcohol, laccase activity increased but the activities of amylase, pectinase, cellulase and xylanase significantly decreased. Basal medium containing softwood kraft lignin in the presence of veratryl alcohol induced laccases above constitutive levels. Ethyl alcohol also stimulated laccase production.