https://www.massey.ac.nz/~ychisti/Biodiesel.pdf

Biodiesel from microalgae.

Use of algae as biofuel sources.

Biotechnology-a sustainable alternative for chemical industry.

Oxygen uptake rate in microbial processes: An overview

Three strains of a spore-forming, Gram-positive, motile, rod-shaped and boron-tolerant bacterium were isolated from soil. The strains, designated 10a(T), 11c and 12B, can tolerate 5 % (w/v) NaCl and up to 150 mM boron, but optimal growth was observed without addition of boron or NaCl in Luria-Bertani agar medium. The optimum temperature for growth was 37 degrees C (range 16-45 degrees C) and the optimum pH was 7.0-8.0 (range pH 5.5-9.5). A comparative analysis of the 16S rRNA gene sequence demonstrated that the isolated strains were closely related to Bacillus fusiformis DSM 2898(T) (97.2 % similarity) and Bacillus sphaericus DSM 28(T) (96.9 %). DNA-DNA relatedness was greater than 97 % among the isolated strains and 61.1 % with B. fusiformis DSM 2898(T) and 43.2 % with B. sphaericus IAM 13420(T). The phylogenetic and phenotypic analyses and DNA-DNA relatedness indicated that the three strains belong to the same species, that was characterized by a DNA G+C content of 36.5-37.9 mol%, MK-7 as the predominant menaquinone system and iso-C(15 : 0) (32 % of the total) as a major cellular fatty acid. In contrast to the type species of the genus Bacillus, the strains contained peptidoglycan with lysine, aspartic acid, alanine and glutamic acid. Based on the distinctive peptidoglycan composition, phylogenetic analyses and physiology, the strains are assigned to a novel species within a new genus, for which the name Lysinibacillus boronitolerans gen. nov., sp. nov. is proposed. The type strain of Lysinibacillus boronitolerans is strain 10a(T) (=DSM 17140(T)=IAM 15262(T)=ATCC BAA-1146(T)). It is also proposed that Bacillus fusiformis and Bacillus sphaericus be transferred to this genus as Lysinibacillus fusiformis comb. nov. and Lysinibacillus sphaericus comb. nov., respectively.

Proposal of Lysinibacillus boronitolerans gen. nov. sp. nov., and transfer of Bacillus fusiformis to Lysinibacillus fusiformis comb. nov. and Bacillus sphaericus to Lysinibacillus sphaericus comb. nov.

https://www.massey.ac.nz/~ychisti/ShearRate.pdf

Shear rate in stirred tank and bubble column bioreactors

https://www.massey.ac.nz/%7Eychisti/Morphology.pdf

Pellet morphology, culture rheology and lovastatin production in cultures of Aspergillus terreus.

https://www.massey.ac.nz/~ychisti/Pellets.pdf

Effects of pellet morphology on broth rheology in fermentations of Aspergillus terreus

A new approach is proposed for the simultaneous determination of the volumetric oxygen transfer coefficient (KLa) and the oxygen uptake rate (OUR) in bioreactors. The methodology is based on modifications of the classical dynamic gassing-in method and the steady-state mass balance method for obtaining the values KLa and OUR, respectively. A polarographic dissolved oxygen electrode is used to monitor the oxygen concentration during a switch of aeration gas composition. The flow rate of the gas phase is not altered so that the hydrodynamics of the bioreactor are not affected during the measurement. Data obtained with this method are compared with the classical methods to show that the proposed technique is robust and reproducible. At a 95% confidence level, the proposed method produced results that were statistically identical to data obtained with the traditional methods. The proposed technique was reproducible to within 4% of the mean value at a 95% confidence level. The proposed method was further proved...

/pdf/simultaneous-determination-of-oxygen-consumption-rate-and-4azaihcrrn.pdf

Simultaneous Determination of Oxygen Consumption Rate and Volumetric Oxygen Transfer Coefficient in Pneumatically Agitated Bioreactors

Atwo-stage feedingstrategyisshowntoimprovetherateofproductionoflovastatinbyAspergillusterreus when compared with conventional batch fermentation. The feeding strategy consisted of an initial batch/fed-batch phase and a semi-continuous culture dilution phase with retention of pelleted biomass in a slurry bubble column reactor. The batch phase served only to build up the biomass for producing lovastatin, a secondary metabolite that inhibits its own synthesis in the producing microfungus. The semi-continuous dilution phase provided nutrients to sustain the fungus, but prevented biomass growth by limiting the supply of essential nitrogen. (Synthesis of lovastatin does not require nitrogen.) The preferred pelleted growth morphology that favors lovastatin synthesis was readily obtained and maintained in the 20 L bubble column used. In contrast, a stirred tank fermentation had a substantially lower production of lovastatin because mechanical agitation damaged the fungal pellets. The two- stage feeding method increased lovastatin production rate by more than 50% in comparison with the conventional batch operation. Rheological data for the fungal broth are presented.  2007 Society of Chemical Industry

/pdf/enhanced-production-of-lovastatin-in-a-bubble-column-by-357eazftwj.pdf

E.M. Rodríguez Porcel

Papers

Shear rate in stirred tank and bubble column bioreactors

Pellet morphology, culture rheology and lovastatin production in cultures of Aspergillus terreus.

Effects of pellet morphology on broth rheology in fermentations of Aspergillus terreus

Simultaneous Determination of Oxygen Consumption Rate and Volumetric Oxygen Transfer Coefficient in Pneumatically Agitated Bioreactors

Enhanced production of lovastatin in a bubble column by Aspergillus terreus using a two-stage feeding strategy