摘要:

AbstractAn acetohydroxyacid synthase (EC 4.1.3.18) which synthesizes α‐acetolactate from pyruvate has been isolated from two differentClaviceps purpureastrains. A purification of about 142‐fold was achieved by ammonium sulfate fractionation and the use of Sepharose 6B and DEAE‐Sepharose CL‐6B columns. The purified enzyme requires thiamine pyrophosphate and a divalent metal ion (Mn2+ or Mg2+) for maximum activity but no FAD. The optimum pH is about 6.0 and the optimum temperature is 40 °C. The enzyme is not inhibited by branched‐chain amino acids neither singly nor in combination. AHAS is strongly inhibited byp‐chloromercuribenzoate and N‐ethylmaleimide. The apparentKmvalues for pyruvate and TPP are 1.7 × 10−2Mand 1.2 ×

ISSN:0233-111X    

DOI:10.1002/jobm.3620290802

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractOne hundred and ten samples representing five types of poultry feed ingredients were mycologically examined. These samples included soybean meal, ground maize, cotton‐seed cake, wheat bran and fish meal (22 samples each). Among the 73 mesophilic fungal species,Aspergillus flavus, A. nigerandA. fumigatuswere the most dominant.A. terreus, A. flavipes, Mucor circinelloides, Scopulariopsis brevicaulis, Penicillium chrysogenum, Fusarium moniliformeandRhizopus stoloniferwere found to be common on a particular ingredient and less common on the remainders. Of the twelve thermophilic and thermotolerant species,A. fumigatus, Thermomyces lanuginosus, Rhizomucor pusillusandThermoascus thermophilusprevailed on one or more type of the different ingredients. Marked variations were observed in the rancid fatty compounds of the different samples and the values ranged between 0.663 and 3.900 mg malonaldehyde per kg sampl

ISSN:0233-111X    

DOI:10.1002/jobm.3620290803

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290805

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractSix organic materials were added to the soil in a field recently showing a high incidence of brown spot disease in maize caused byPhysoderma maydis.All the amendments lowered significantly the occurrence of the disease in comparison to the unamended control. However, the ability to suppress the disease differed substantially among the amendments. Rice bran and rice straw were most effective in this respect. The suppression of the disease appeared to be related to an increased microbial activity in the soil.

ISSN:0233-111X    

DOI:10.1002/jobm.3620290806

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290807

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractSesbania rostrataand fifteen species ofAeschynomeneare tropical legumes which can grow in flooded soils because they have both root and stem nodulation. They are of particular agronomic interest because of their potential for maintaining soil fertility. Three genera of rhizobia are associated symbiotically with these stem nodulating legumes:RhizobiuminfectsS. rostrataand someAeschynomenespecies;Azorhizobiumis specific toS. rostrataand can live outside the plant;Bradyrhizobiuminfects onlyAeschynomenespecies.InS. rostrataroot infection occurs by root hair curling, whereas stem nodulation is achieved by entry of bacteria at the site of emerging adventitious rootlets. Many studies have reported that infection by thread formation is observed on both roots and stems ofS. rostrata.InS. rostrata, the process of root infection has been shown to follow several stages: recognition and attachment of rhizobia to the root surfaces induction of root hair curling; formation of infection threads that guide bacteria to the adjacent cortical root cells; release of bacteria into the cytoplasm of host cells where they are enveloped by host plasmalemm.Stem infection ofS. rostratahas been shown to have four stages: rhizobial penetration in degenerated cortical cells through cracks at the site of emerging rootlets;Rhizobiumproliferates in the intercellular cavities and initiates meristematic nodules; infection threads form in the intercellular cavities and in the host cells; rhizobia are intercellularly released by an endocytotic process.Most of the stem nodulatedAeschynomenespp. have displayed the same process of root infection asS. rostrata. A.indicais an exception in that it appears that the path of infection is constituted by the rupture of tissue restricted to the place of rootlet emergence. No infection thread formation is observed inA. indica.The unique characteristic of all stem‐nodulating legumes is the presence of pre‐determined nodulation sites on their stems. InAeschynomene, the process of stem infection does not involve formation of infection threads but is effected by penetration ofRhizobinumthrough cracks which surround the root primordia. This penetration is followed by hydrolysis of host epidermic cell walls causing the release of the bacteria into cell cytoplasm.Stem‐nodulating legumes infection depends on both ecological and intrinsic legumes factors.It is important to note that the nitrogen fixation ofS. rostrata. A. afraspera, andA. scabrawas not inhibited by mineral nitrogen.The role of leaghemoglobin in the regulation and protection of nitrogenase activity is well established. Recently, it was suggested that superoxide dismutase. which is present at high levels in bacteroides isolated from root and stem nodules of a few stem‐nodulating legumes, would be another regulator and protector of the process of nitrogen f

ISSN:0233-111X    

DOI:10.1002/jobm.3620290808

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290810

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractIn the present study, the production of β‐glucosidase and endoglucanase and the pattern of their corresponding polymorphic forms occurring in the extracellular and cytosolic filtrates ofChaetomium fusisporale(ATCC 64772) has been studied. WhenC. fusisporalewas grown on carboxymethyl cellulose (CMC) as the sole carbon source, the extracellular fractions contained most of these enzymes. The distribution of the enzymes varied with the age of the culture. By the use of electrophoretic techniques the presence of two forms of β‐glucosidase, i.e. β‐GLU II and β‐GLU III was detected in extracellular and cytosolic filtrates at early stages of growth, while at later stages two more isozymes of β‐glucosidase, i.e. β‐GLU I and β‐GLU IV, only appeared in the cytosolic filtrates. Similary, endoglucases isozymes EG I and EG II were present in both fractions at early stages of growth but at later stages, with the production of perithecia, EG III appeared. Thus, EG III, β‐GLU I and β‐GLU IV may indicate that they are correlated with the development of the fungus. In order to differentiate further between the multiple molecular forms of these enzymes two of them have been characterized with respect to temperature, pH, ethylenediamine tetra‐aceti

ISSN:0233-111X    

DOI:10.1002/jobm.3620290811

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290813

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractNutritionally balanced heterokaryons of the naturally diploid, asexual yeast,Candida albicansare produced by fusing protoplasts of complementing auxotrophic strains. Spontaneous unidirectional internuclear transfers of an intact gene linkage group in established heterokaryons is demonstrated. Evidence is presented that a transfer event (i) typically involves a single chromosome which is added to the resident homologues of a recipient nucleus, (ii) can occur equally well in either direction between complementing nuclei and (iii) may encourage gene conversion at transferred loci in the recipient nucleus. The bearing of these findings on application of protoplast fusion to parasexual genetic analysis ofC. albicansis discussed.

ISSN:0233-111X    

DOI:10.1002/jobm.3620290814

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY