Formation of spontaneous asporogenic variants of Bacillus thuringiensis subsp. galleriae in continuous cultures

Sachidanandham, Ramaiah; Jayaraman, Kunthala

doi:10.1007/bf00175739

Cited by 13 publications

(14 citation statements)

References 17 publications

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“…galleriae that the strain segregates to asporogenic variants in long term continuous cultures [6]. In addition, it also exhibits maintenance requirement under unbalanced growth conditions.…”

Section: Estimation Of Maintenance Coefficientmentioning

confidence: 99%

Maintenance requirements in Bacillus sphaericus 1593M under dual substrate limitations estimated at zero growth rate in a total cell retention culture

Sachidanandham¹,

Kalaiselvi²

1998

Bioprocess Engineering

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The maintenance requirement(s) exhibited by Bacillus sphaericus 1593M was clearly established from the data on the steady state continuous cultures wherein the growth yield was found to be increasing with increase in dilution rate (4). In the present study we have attempted to estimate the maintenance coef®cient of B. sphaericus 1593M by achieving zero growth rate in a total cell retention culture (TCRC). Zero growth rate was achieved at a cell density of 5.57 g l A1 which remained constant reecting a steady state in the TCRC. Based on the substratē ux calculations, maintenance coef®cient was found to be 0.087 h A1 . Further, using this data of maintenance coef®-cient, steady state cell density and substrate pro®les in continuous cultures of B. sphaericus 1593M were predicted by simulation, which showed a close relationship to that of the experimental data.

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Section: Estimation Of Maintenance Coefficientmentioning

confidence: 99%

Maintenance requirements in Bacillus sphaericus 1593M under dual substrate limitations estimated at zero growth rate in a total cell retention culture

Sachidanandham¹,

Kalaiselvi²

1998

Bioprocess Engineering

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“…In fact, it is well known that continuous culture of Btk or Bt. galleriae caused the appearance of asporogenous variants (Spo -) [7,25]. According to Sachidanandham and Jayaraman [25], the absence of critical nutritional factors in the culture medium, which could be essential for the maintenance of genetic elements governing sporulation, might have also led to the loss of sporulation.…”

Section: Fed-batch With Two Feeds At 10 and 20 H (Run # 3)mentioning

confidence: 99%

“…galleriae caused the appearance of asporogenous variants (Spo -) [7,25]. According to Sachidanandham and Jayaraman [25], the absence of critical nutritional factors in the culture medium, which could be essential for the maintenance of genetic elements governing sporulation, might have also led to the loss of sporulation. Moreover, in the continuous culture of Bacillus sphaericus 2362, the appearance of asporogenous variants was also observed and the entomotoxicity of fermented product against mosquito was also significantly decreased as compared to the wide-type variant (spo ? )…”

Section: Fed-batch With Two Feeds At 10 and 20 H (Run # 3)mentioning

confidence: 99%

Batch and fed-batch fermentation of Bacillus thuringiensis using starch industry wastewater as fermentation substrate

Tyagi

Valero

et al. 2009

Bioprocess Biosyst Eng

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Bacillus thuringiensis var. kurstaki biopesticide was produced in batch and fed-batch fermentation modes using starch industry wastewater as sole substrate. Fed-batch fermentation with two intermittent feeds (at 10 and 20 h) during the fermentation of 72 h gave the maximum delta-endotoxin concentration (1,672.6 mg/L) and entomotoxicity (Tx) (18.5 x 10(6) SBU/mL) in fermented broth which were significantly higher than maximum delta-endotoxin concentration (511.0 mg/L) and Tx (15.8 x 10(6) SBU/mL) obtained in batch process. However, fed-batch fermentation with three intermittent feeds (at 10, 20 and 34 h) of the fermentation resulted in the formation of asporogenous variant (Spo-) from 36 h to the end of fermentation (72 h) which resulted in a significant decrease in spore and delta-endotoxin concentration and finally the Tx value. Tx of suspended pellets (27.4 x 10(6) SBU/mL) obtained in fed-batch fermentation with two feeds was the highest value as compared to other cases.

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“…galleriae (Btg) was obtained from the laboratory strain collection of the Centre for Biotechnology, Anna University, Chennai, India and maintained on nutrient broth (NB) agar plates at 4°C. Medium composition, nutrient broth (NB), glucose yeast extract (GY) medium (Sachidanandham & Jayaraman 1993) and Glucose-YE-Aminoacids medium (GYA) (Sachidanandham et al 1996). Feed solutions for fed-batch cultivation were glucose: 80.0 g/l; yeast extract: 80.0 g/l and ammonium sulphate: 13.6 g/l.…”

Section: Microorganism and Mediamentioning

confidence: 99%

Impact of balanced substrate flux on the metabolic process employing fuzzy logic during the cultivation of Bacillus thuringiensis var. Galleriae

Anderson

Jayaraman

2005

World J Microbiol Biotechnol

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The insecticidal crystal protein (ICP) synthesized at the onset of sporulation by Bacillus thuringiensis var. galleriae (Btg) is lethal against specific pests. Attempts were made to enhance the synthesis of biomass and ICP by Btg employing process optimization strategies. The process optimization was carried out with residual glucose concentration control in a bench scale bioreactor. A fuzzy logic-based feedback control system for maintaining the residual glucose concentration at a constant level during cultivation was developed in LabVIEW. This control system indicated the possibilities in providing a balanced substrate flux during cultivation. The identified optimum level of 2.72 g/l in residual glucose concentration was maintained by fed-batch cultivation with glucose and yeast extract fed at equal concentration with the above control system. High cell density of 16.0 g/l with specific growth rate of 0.69 h )1 was obtained during the cultivation. The balanced flux of substrate during cultivation has resulted in the enhanced synthesis of biomass and ICP. This optimized process could be commercially exploited by comparing the fluxes of basal compounds in different media sources used in fermentation.

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Formation of spontaneous asporogenic variants of Bacillus thuringiensis subsp. galleriae in continuous cultures

Cited by 13 publications

References 17 publications

Maintenance requirements in Bacillus sphaericus 1593M under dual substrate limitations estimated at zero growth rate in a total cell retention culture

Maintenance requirements in Bacillus sphaericus 1593M under dual substrate limitations estimated at zero growth rate in a total cell retention culture

Batch and fed-batch fermentation of Bacillus thuringiensis using starch industry wastewater as fermentation substrate

Impact of balanced substrate flux on the metabolic process employing fuzzy logic during the cultivation of Bacillus thuringiensis var. Galleriae

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