A preliminary study on cultivation of Mucor plumbeus: For microbial oil production using molasses

Sugarcane molasses, sugarcane trash and bagasse are the major by-products generated in cane sugar production process. Conversion of these by -products into valuable products has the potential to improve the profitability of the sugarcane industry. Biofuels are one of the value- added products. However, the profits from the production of low value biofuels such as bioethanol and biodiesel are marginal under current market conditions . In recent years, production of high value advanced drop- in biofuels from renewable carbohydrate feedstocks has gained increasing interests worldwide. The research team at QUT is working together with industrial partners on advanced biofuels production from sugarcane processing by-products through a two-stage process. In the first stage, microbial oils are prod uced by oleaginous microorganisms . In the second stage, advanced biofuels are produced through hydro deoxygenation of either microbial oils extracted from microbial biomass or microbial oils obtained from hydrothermal liquefaction of microbial biomass. In this study, microbial oil production by an oleaginous filamentous fungus , Mucorplumbeus , was carried out using molasses as a carbon source. Morphology control strategy and nutrient optimisation were firstly developed to improve biomass and microbial oil production. Furthermore, microbial oil production by M. plumbeus was scaled up from shake flasks to laboratory scale stirred tank reactors . Inoculation of crushed fungal pellet biomass led to the formation of dispersed short hyphae in reactors and improved biomass and oil production. Finally, the inoculation strategy was demonstrated in a 1 000 L reactor at Mackay Renewable Biocommodity Pilot Plant

Draft genome sequence of Caloramator mitchellensis, a thermoanaerobe isolated from the waters of the Great Artesian Basin

The genome sequence of Caloramator mitchellensis strain VF08, a rod-shaped, heterotrophic, strictly anaerobic bacterium isolated from the free-flowing waters of a Great Artesian Basin (GAB) bore well located in Mitchell, an outback Queensland town in Australia, is reported here. The analysis of the 2.42-Mb genome sequence indicates that the attributes of the genome are consistent with its physiological and phenotypic traits

Prospecting for novel enzyme activities and their genes in filamentous fungi from extreme environments

23 page(s

Solubilization and degradation of polychlorinated biphenyls (PCBs) by naturally occurring facultative anaerobic bacteria

A combination of solubilization and degradation is essential for the bioremediation of environments contaminated with complex polychlorinated biphenyls (PCB) mixtures. However, the application of facultative anaerobic microorganisms that can both solubilize and breakdown hydrophobic PCBs in aqueous media under both anaerobic and aerobic conditions, has not been reported widely. In this comprehensive study, four bacteria discovered from soil and sediments and identified as Achromobacter sp. NP03, Ochrobactrum sp. NP04, Lysinibacillus sp. NP05 and Pseudomonas sp. NP06, were investigated for their PCB degradation efficiencies. Aroclor 1260 (50 mg/L), a commercial and highly chlorinated PCB mixture was exposed to the different bacterial strains under aerobic, anaerobic and two stage anaerobic–aerobic conditions. The results confirmed that all four facultative anaerobic microorganisms were capable of degrading PCBs under both anaerobic and aerobic conditions. The highest chlorine removal (9.16 ± 0.8 mg/L), PCB solubility (14.7 ± 0.93 mg/L) and growth rates as OD600 (2.63 ± 0.22) were obtained for Lysinibacillus sp. NP05 under two stage anaerobic-aerobic conditions. The presence of biosurfactants in the culture medium suggested their role in solubility of PCBs. Overall, the positive results obtained suggest that high PCB hydrolysis can be achieved using suitable facultative anaerobic microorganisms under two stage anaerobic-aerobic conditions. Such facultative microbial strains capable of solubilization as well as degradation of PCBs under both anaerobic and aerobic conditions provide an efficient and effective alternative to commonly used bioaugmentation methods utilizing specific obligate aerobic and anaerobic microorganisms, separately

Application of Genetic Engineering for Strain Improvement in Filamentous Fungi

16 page(s

Making a Bacterial Thermophilic Enzyme in a Fungal Expression System

This unit describes production of a bacterial thermophilic xylanase enzyme in an industrially exploited filamentous fungus, Trichoderma reesei. Successful expression of a gene of interest in a heterologous host involves front-end design of the expression constructs using bioinformatics tools, making the constructs in the laboratory, and introducing them into the expression host. This is followed by synthesis and characterization of the gene product on a laboratory scale and optimization of the cultivation parameters in a controlled, scaled-up fermentation. The thermophilic xylanase B (XynB) enzyme from the bacterium Dictyoglomus thermophilum discussed here can be easily purified by heat-precipitation from the culture supernatant of the mesophilic host. A functional XynB can also be produced in Escherichia coli, but at a lower yield compared to that obtained in T. reesei. The protocol provided here can be adapted to various other proteins and filamentous fungal hosts.</p

Effective degradation of polychlorinated biphenyls by a facultative anaerobic bacterial consortium using alternating anaerobic aerobic treatments

Polychlorinated biphenyls (PCBs) are synthetic mixtures of chlorinated hydrocarbon compounds that were widely used in the past and still found in the environment due to their highly recalcitrant nature. A combination of anaerobic dechlorination and aerobic oxidation is essential to degrade these PCB mixtures into less toxic products. It was hypothesized that due to the complexity of PCB mixtures, a consortium of carefully selected suitable microbial species will perform better than the application of individual microbes. In the present study, biodegradation of the commercial PCB mixture, Aroclor 1260, was studied under two different combined anaerobic-aerobic conditions, namely, alternating (AN) and two stage (TS). The facultative anaerobic bacterial consortium consisted of naturally occurring Achromobacter sp. NP03, Ochrobactrum sp. NP04 and Lysinibacillus sp. NP05. These bacteria were found capable as individuals of solubilizing and degrading PCBs under both anaerobic and aerobic conditions. 49.2 ± 2.5% total reduction of the original 50 mg/L Aroclor 1260 mixture was achieved after 2 weeks in AN treatment whereas the reduction was only 24.44 ± 2.46% in TS treatment. At the end of week 6, a yield of 17.63 ± 0.91 mg/L chloride released was measured under AN condition compared to 11.79 ± 1.28 mg/L measured under TS condition. The overall results suggested that the microbial consortia capable of degrading and utilizing PCBs under both, anaerobic and aerobic conditions achieved better PCB degradation by repeated exposure to short periods of anaerobic and aerobic conditions alternatingly rather than the conventional two stage anaerobic-aerobic conditions.</p

Draft genome sequence of caloramator mitchellensis, a thermoanaerobe isolated from the waters of the Great Artesian Basin

The genome sequence of Caloramator mitchellensis strain VF08, a rod-shaped, heterotrophic, strictly anaerobic bacterium isolated from the free-flowing waters of a Great Artesian Basin (GAB) bore well located in Mitchell, an outback Queensland town in Australia, is reported here. The analysis of the 2.42-Mb genome sequence indicates that the attributes of the genome are consistent with its physiological and phenotypic traits

Expression of the mammalian peptide hormone obestatin in Trichoderma reesei

The filamentous fungus Trichoderma reesei is an expression host widely exploited for the production of recombinant proteins. However, its capacity for expressing small peptides (<20 kDa) has remained largely uncharted to date. In this work, we have produced the hormone peptide obestatin fused to the hydrophobin I tag (Obe-HFBI), using the T. reesei cellobiohydrolase I core (CBHI) or xylanase 2 (XYN2) pro-region as a carrier and the cbh1 promoter for gene expression, in high protein-low protease producing mutant strains T. reesei Rut-C30 and HEPI. The yield of obestatin was improved from about 300 ng/ml to up to 5.5 μg/ml through adaptive laboratory evolution and modifications to the cultivation strategy, which included adjustments of the type and ratio of carbon and nitrogen sources used in the medium. The successful expression of Obe-HFBI demonstrated the potential of T. reesei as an expression host for small peptides and further enhancement of the recombinant yield through modification of culture conditions.8 page(s

Heterologous gene expression in filamentous fungi : a holistoc view

As scavengers of recalcitrant polymers in the nature, filamentous fungi are excellent secretors of proteins outside the growing mycelium. This characteristic has been targeted and systematically improved in industrially-exploited production strains. Over the last five years there has been a significant shift from one-gene-at-a-time approaches to wider understanding of the organism, made possible, for example by gene array and proteome technologies that can now also be applied to filamentous fungi. This has presented novel opportunities for studies into gene regulation under specific conditions such as a particular carbon source or developmental stage with a view of advancing the basic knowledge and gaining information that can be applied for strain and process improvement. Filamentous fungi offer enormous potential for efficient and large scale production of heterologous gene products. Importantly, protein secretion provides a platform for the eukaryotic style posttranslational modification of gene products. Fungi are cheap to cultivate and down-stream processing is made easy with no need to break cells open for product recovery. In order to capitalize on fungi as heterologous production hosts, research is now directed to revealing the cellular mechanisms for internal protein quality control, secretion stress, functional genomics of protein expression and secretion, protein modification and linking the physiology to productivity.27 page(s