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    A study of some wool-disintegrating bacteria, by "Animal" : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey Agricultural College
    (Massey University, 1932) Hursthouse, Katrine Fearon; Animal
    The purpose of this thesis is the isolation and study of the bacteria that ret the wool of living sheep in New Zealand, the study of the distribution of wool-retting bacteria and of some of the conditions in which they bring about decay. It is also desired to show what effect; the wool retting bacteria have upon the hoof of sheep - a substance which like wool, consists largely of keratin - and what effect the hoof rotting bacteria have upon wool. [From Purpose and scope of thesis]
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    Methodology of culture maintenance and inoculum development for production of solvents by Clostridium acetobutylicum : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Biotechnology at Massey University
    (Massey University, 1985) Gutierrez, Noemi A
    Various methods of culture maintenance and inoculum develop­ment were evaluated for their effectiveness in conserving and improving the property of 2 strains of Clostridium acetobutyicum, namely NCIB 2951 and NRRL B-594, to produce solvents by fermentation of whey permeate. The majority of the methods were effective in maintaining the viability and solventogenic property of the organism. However, since in some cases the viability was maintained but the solventogenic property was not, it is clear that the latter should be used as the index in determining the storage life and time of reprocessing of the stock culture. The methods of culture maintenance investigated included refrigeration at 4°c in distilled water, in phosphate buffer and in Cooked Meat Medium containing glucose ( CMMG) ; by freezing at -20°c in distilled water and in phosphate buffer; by drying in soil and by lyophilization ( freeze drying); and by periodic transfer in CMMG and in whey permeate containing yeast extract. Maintenance of the stock cultures at -20° C in distilled water was found to be the most efficient for the storage stability of both strains of organism. The viability and the potential to produce high solvent concentrations, primarily butanol were maintained without any significant loss after 9 months and 12 months, for strain NCIB 2951 and strain NRRL B-594, respectively. The criteria important for a commercial fermentation, i.e., sugar utilization, yield and butanol production rate, remained stable during storage by this method. It was observed that periodic transfer was a poor method as the culture lost their solventogenic property despite remaining viable. The other preservation methods were not as satisfactory as freezing in distilled water at -20°c since the fermentation ability degenerated to some extent after 9 months of storage. Therefore, after such a period reprocessing of the stock cultures kept by these methods is necessary to revive the cultures and minimize degeneration. The repeated use of the stock cultures was found to be deleterious and should be avoided. The inoculum development procedure investigated to maximize fermentation efficiency included the conventional heat shocking of the stock culture; variation in the number of culture stages; use of gassing as an index of transfer time; and the use of different levels of inoculum size. The strain differences which exist between NRRL B-594 and NCIB 2951 influenced how the inocula from these strains should be propagated prior to fermentation. Strain NRRL B-594 responded to heat shocking while strain NCIB 2951 did not. Neither ethanol nor butanol treatment of the stock cultures of the latter were advantageous. Using a 3-stage inoculum development procedure, the ferment­ation efficiency of strain NRRL B-594 was improved by employing heat shocking at 80C for 15 min in the revival stage of the stock culture. The germination factors for the spores of NCIB 2951 await identification. However, by using the presence of highly motile cells as an index in transferring from the revival stage, the inoculum develop­ment procedure resulted in a significantly higher butanol concentration value and production rate. Thus, the revival stage was the most critical.
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    A statistical approach to medium optimization for growth and toxin production by the bacterium Bacillus thuringiensis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Biotechnology at Massey University, Palmerston North, New Zealand
    (Massey University, 1976) Tran, Quan Dat
    Bacillus thuringiensis is a Gram positive spore-forming bacterium. Knowledge of its pathogenicity against the larval stages of certain lepidopterous insects has been known for over 70 years. Ishiwata (1902) was the first to isolate it from dying silkworm larvae. Later Berliner (1915) isolated it from sick larvae of Anagasta kuhniella. He noted the existence of a parasporal body or "Rostkorper" in sporulated cells. These observations were confirmed by Mattes (1927), but it was not until 1953 that Hannay (1953) characterized the parasporal body as a crystal. The crystal has since been known to play a key role in the pathogenicity towards the most susceptible lepidopterous larvae. In recent years a considerable degree of interest has been aroused on the use of biological methods for insect control as against the use of chemical insecticides. Among many biological products considered as insect control agents, the crystal produced in the bacterium B. thuringiensis is one of the most hopeful. Industrial organisations in several countries are presently engaged in fundamental research and commercial scale production of insecticidal preparations based on this bacterium (Falcon, 1971; Pendleton, 1969). Apart from the crystal, which might be considered as an enterotoxin, a number of exotoxins are also known or postulated to be produced by B. thuringiensis. Heimpel (1967a) suggested the following nomenclature: δ -endotoxin, or the proteinaceous crystal; α-exotoxin, a lecithinase C or phospholipase C; β -exotoxin, a thermostable exotoxin or "fly factor"; γ -exotoxin (an enzyme that clears egg yolk agar, not yet identified). The toxicity for insects of the β -exotoxin and the δ -endotoxin has been substantiated, but the efficiency of the so-called γ -exotoxin has not been proved. Quite recently Krieg (1971) suggested that the α -exotoxin is not identical with lecithinase C. He concluded that the α -exotoxin is a thermosensitive exotoxin of proteinaceous character which is produced during growth phase by strains of B. thuringiensis and of B. cereus. Krieg (1970) also isolated a relative heat stable bacteriocin produced by B. thuringiensis which he called Thuricin. He suggested that this is a polypeptide and can cause inhibition of growth of Gram positive bacteria and antagonism between several strains of B. thuringiensis.[FROM INTRO]
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    The mycoflora of fleece wool : a thesis presented in partial fulfilment of the requirement for the degree of Master of Science in Microbiology at Massey University
    (Massey University, 1976) Lim, Soo Chun
    A study has been made of the variation in the total population of fungi within sheep fleece in vivo with time, and also of the types of moulds and yeasts present within this environment. Fungi were isolated by dilution plating and by the brush technique at the two temperatures of 25C and 37C. Considerably larger numbers of fungi were isolated at the lower temperature. There was no apparent correlation between fungal numbers within fleece wools and the environmental rainfall, either at the time of sampling or on a monthly average basis. The total population of moulds able to grow at 25C did, however, vary with the average monthly environmental temperature. No such correlation existed for moulds growing at 37C nor yeasts at either temperature. Fungal numbers were unaffected by pretreatment of the sheep with commonly used insecticides variously applied, and seemed more related to general environmental conditions than to mode of pretreatment. Possible factors contributing to variations in the total fungal populations of fleece wools are discussed. The types of fungi isolated from wools could be grouped into very frequently isolated species, e.g. Alternaria alternata, Phoma spp., Torulopsis candida, frequent species, e.g. Mucor racemosus, Aspergillus fumigatus, occasional species, e.g. Cladosporium herbarum, Epicoccum purpurascens, Fusarium oxysporum and very occasional species, e.g. Aspergillus niger, Geotrichum candidum, Peyronellaea glomerata. A study of the spatial distribution of the fungi within the fleece was made by an impression technique involving both microscopic and cultural examinations. Most fungi were present in the median parts of the staple and numbers decreased towards the tips and basal parts of the fleece. Again, the most frequent types included Alternaria alternata, Fusarium culmorum and Phoma spp. Of the 68 isolated species, 19 were tested for their ability to degrade autoclaved and propylene oxide sterilised wool in vitro. While Aspergillus niger and Penicillium canescens were consistently unable to degrade either of the wools, most of the tested species degraded both autoclaved and propylene oxide sterilised wool. The degradation of wool by these fungi resulted in the release into the culture medium of cortical cells from the wool fibres. It is postulated that degradation occurred as a result of the breaking down of cementing materials holding the cortical cells together and did not involve true keratin digestion. Wool degraded by fungi was densely stained by lactophenol cotton blue. It is suggested that this activity could be useful in estimating the ability of fungi to degrade wool, even though undegraded wool was lightly and irregularly stained. As several fungi were shown to be capable of breaking down wool in vitro, further tests were made to determine which of these species are potentially able to grow within fleece in vivo. Of those able to grow at skin temperature and which were unaffected by the fatty materials present in wool, Sordaria fimicola . and Aureobasidium pullulans were the two species most likely to grow in the natural fleece environment. The significance of the work reported here is discussed. Many of the fungi commonly isolated from fleece wools have been reported to cause opportunistic fungal infections in man and animals and are also capable of spoiling refrigerated meats. Thus knowledge of the presence of these fungi in wools is necessary to help avoid problems in public health.