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A new bacterial strain, isolated from groundwater contaminated with explosives, was characterized as a pink-pigmented facultative methylotroph, affiliated to the genus Methylobacterium. The bacterial isolate designated as strain GW2 was found capable of producing the homopolymer poly-3-hydroxybutyrate (PHB) from various carbon sources such as methanol, ethanol, and succinate. Methanol acted as the best substrate for the production of PHB reaching 40 % w/w dry biomass. PHB accumulation was observed to be a growth-associated process, so that there was no need for two-step fermentation. Optimal growth occurred at 0.5 % (v/v) methanol concentration, and growth was strongly inhibited at alpha concentration above 2 % (v/v). Methylobacterium sp. strain GW2 was also able to accumulate the copolyester poly-3-hydroxybutyrate-poly-3-hydroxyvalerate (PHB/HV) when valeric acid was supplied as an auxiliary carbon source to methanol. After 66 h, a copolymer content of 30 % (w/w) was achieved with a PHB to PHV ratio of 1:2. Biopolymers produced by strain GW2 had an average molecular weight ranging from 229,350 to 233,050 Da for homopolymer PHB and from 362,430 to 411,300 Da for the copolymer PHB/HV.

Bacillus thuringiensis subsp kurstaki was grown in batch and fed batch cultures using wastewater sludge as a raw material. A simple fed batch strategy based on dissolved oxygen measurement during the fermentation cycle was developed in this work. It was established that while shifting the process strategy from batch to fed batch, the maximum spore concentration was increased from 5.62 × 10 8 to 8.6 × 10 8 colony forming units per cm 3 and resulted in an increase of entomocidal activity from 13 × 10 9 to 18 × 10 9 spruce budworm potency units per dm 3 . Higher entomotoxicity was recorded at low spore concentration using wastewater sludge as a raw material whereas low entomotoxicity was reported at high spore concentration in synthetic medium.

/npsi/ctrl?action=rtdoc&an=3539342&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=3539342&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur.Applied Microbiology and Biotechnology, 77, 2, Production of Poly-β-Hydroxybutyrate ( Abstract Maple sap, an abundant natural product especially in Canada, is rich in sucrose and thus may represent an ideal renewable feedstock for the production of a wide variety of value-added products. In the present study, maple sap or sucrose was employed as a carbon source to Alcaligenes latus for the production of poly-β-hydroxybutyrate (PHB). In shake flasks, the biomass obtained from both the sap and sucrose were 4.4±0.5 and 2.9±0.3 g/L, and the PHB contents were 77.6±1.5 and 74.1±2.0%, respectively. Subsequent batch fermentation (10 L sap) resulted in the formation of 4.2±0.3 g/L biomass and a PHB content of 77.0±2.6%. The number average molecular weights of the PHB produced by A. latus from maple sap and pure sucrose media were 300±66×10 3 and 313±104×10 3 g/mol, respectively. Near-infrared, 1 H magnetic resonance imaging (MRI), and 13 C-MRI spectra of the microbially produced PHB completely matched those obtained with a reference material of poly[(R)-3-hydroxybutyric acid]. The polymer was found to be optically active with [α] 25 D equaled to −7.87 in chloroform. The melting point (177.0°C) and enthalpy of fusion (77.2 J/g) of the polymer were also in line with those reported, i.e., 177°C and 81 J/g, respectively.

In this investigation, ammonium hydroxide and acetic acid were used as pH control agents during Bacillus thuringiensis (Bt) fermentation in a pilot scale fermentor (150-l) employing two secondary wastewater sludges from two different wastewater treatment plants (CUQS and JQS) and semi-synthetic soybean meal medium as raw materials. Regardless of the cultivation medium, a substantial increase in total cell count, spore count, protease activity and entomotoxicity was achieved when the pH of the culture was controlled using NH 4 OH/ CH 3 COOH. At harvest, total cell count increased by almost 17%, 33% and 25%; protease activity was enhanced by 12%, 33% and 53% and maximal spore count augmented by almost 28%, 48% and 33% in CUQS, JQS and soybean medium, respectively. Entomotoxicity potency was improved by 22%, 21% and 14% in CUQS, JQS and soybean medium, respectively compared to results obtained with NaOH/H 2 SO 4 as pH control agents. A higher entomotoxicity was also observed using sludge compared to the soybean medium. This improvement of the Bt process performance was a consequence of the addition of rapidly utilizable carbon and nitrogen source through pH control, which stimulated endotoxin production in the crystal and enhanced sporulation.

Studies were conducted on the production of Bacillus thuringiensis (Bt)-based biopesticides to ascertain the performance of the process in shake flasks, and in two geometrically similar fermentors (15 and 150 l) utilizing wastewater sludge as a raw material. The results showed that it was possible to achieve better oxygen transfer in the larger capacity fermentor. Viable cell counts increased by 38-55% in the bioreactor compared to shake flasks. As for spore counts, an increase of 25% was observed when changing from shake flask to fermentor experiments. Spore counts were unchanged in bench (15 l) and pilot scale (5.3-5.5 e(+08) cfu/ml; 150 l). An improvement of 30% in the entomotoxicity potential was obtained at pilot scale. Protease activity increased by two to four times at bench and pilot scale, respectively, compared to the maximum activity obtained in shake flasks. The maximum protease activity (4.1 IU/ml) was obtained in pilot scale due to better oxygen transfer. The Bt fermentation process using sludge as raw material was successfully scaled up and resulted in high productivity for toxin protein yield and a high protease activity.

Wastewater sludge is a complex raw material for fermentation and requires pre-treatment in order to transform less biodegradable compounds into more easily degradable ones. In this study, sludge was treated by thermo-alkaline and oxidative pre-treatment methods and subjected to Bacillus thuringiensis fermentation in bench scale fermentors under controlled conditions. Thermo-alkaline treatment was found to be an effective process in order to enhance the entomotoxicity tested against spruce budworm. The total cell and spore counts were improved by 40 and 46%, respectively as compared to that using the untreated sludge. The final entomotoxicity potency increased from 12.3 · 10 9 SBU/l of the raw sludge to 16.6 · 10 9 SBU/l of the thermo-alkaline pre-treated sludge. The improvement of the process performance was attributed to a better oxygen transfer due to decrease in media viscosity and an improvement of nutrient availability due to the sludge solubilization and biodegradability.