Biopesticide production using Bacillus thuringiensis kurstaki by valorization of starch industry wastewater and effluent from aerobic,anaerobic digestion

Introduction Unconventional alternatives such as aerobic and anaerobic effluent from starch industry contain essential nutrients for Btk active ingredient synthesis.Effluent from starch industry is rich in carbon and nitrogen and can replace expensive feedstock used during the fermentation process.Objectives The main objective of this study was to achieve a biopesticide formulation from starch industry wastewater(SIW)with high entomotoxicity(UI/ml)of larvae comparable to Foray 76B,which is a commercial biopesticide.Methods Bacillus thuringiensis var kurstaki HD1(Btk)strain was cultivated and sub-cultured to aerobic,anaerobic digested effluent and SIW.Pre-treatment was carried on these different substrates to enhance the residual carbon required for Btk growth and delta endotoxin synthesis.After 48 hours of fermentation,cells count and delta-endotoxin were determined.A biopesticide formulation containing fermented broth and adjuvants was fed to larvae to determine larvae mortality.Results Btk cell growth and sporulation profile in SIW media displayed a high total cell count and viable spores compared to btk growth in anaerobic or aerobic media after 48h fermentation.The maximum endotoxin concentration in the SIW medium was 435μg/mL,whereas,in anaerobic and aerobic effluent,the maximum concentrations were at 161μg/mL and 136μg/mL,respectively.When acidic treatment was performed at pH 2 for these substrates,entomotoxicity obtained from aerobic and anaerobic biopesticide formulations displayed significantly higher entomoxicity than the untreated ones.The entomotoxicity of SIW treated at pH 2 was equivalent to the standard Foray 76B which is 20,000 IU/μL.Conclusion Anaerobic and aerobic effluent did not contain enough total organic carbon to augment Btk growth and entomo-toxicity.Substrates pre-treated at pH 2 provided significant organic matter for Btk growth and resulted in larval mortality equivalent to the com ercial biopesticide Foray 76B.

Comparative study on production and characterisation of extracellular polymeric substances(EPS)using activated sludge fortified with crude glycerol from different biodiesel companies

Extracellular polymeric substances(EPS)are eco-friendly and economical biopolymers with a significant role in pollutant removal,bio-flocculation,settling and dewatering of activated sludge.In this study,growth profile and EPS production by an EPS-producing microbial strain(isolated from wastewater sludge or WWS)was studied using activated sludge fortified with glycerol.The study compared three crude glycerol samples as carbon sources from different biodiesel companies(BIO-LIQ,BIOCARDEL,ROTHSAY)and their effect on EPS production and characterisation was observed.The maximum slime EPS(S-EPS)concentration(12.34 g/L)was produced when sludge fortified with BIO-LIQ crude glycerol was used,higher than pure glycerol(10 g/L)at 72 h.The S-EPS was enhanced(16 g/L)when purified BIO-LIQ glycerol(by acid treatment)was used.It was also observed that S-EPS concentration increased 1.6-2.6 times by using sludge fortified with glycerol as compared to only glycerol(no sludge)as EPS production medium.In addition,the S-EPS produced from different glycerol samples yielded different characteristics in terms of protein-carbohydrate content,flocculation activity and dewaterability.The S-EPS from purified BIO-LIQ glycerol(with sludge)gave maximum flocculation activity and dewaterability i.e.93.71%and 60.2%respectively.The comparison between Ca(OH)2 and NaOH used as alkaline sludge pre-treatment methods revealed that the EPS produced from Ca(OH)_(2)-treated sludge fortified with glycerol solutions to be better in terms of protein content,flocculation activity and dewaterability.Structural composition analysis using Fourier Transform Infrared Spectroscopy(FT-IR)revealed the presence of distinct functional groups(carboxyl,hydroxyl,amine groups)in the produced S-EPS.

Biodiesel production from microbial lipid obtained by intermittent feeding of municipal sludge and treated crude glycerol

In the present study,municipal secondary sludge and purified glycerol(obtained after acid treatment of crude glycerol)were used together for lipid production using intermittent feeding strategy.Intermittent sludge feeding strategy(sludge SS 30 g/L)resulted in a higher biomass(54.99 g/L)and lipid concentration(25.35 g/L)at 96 h when compared to 35 g/L SS single sludge feeding or control strategy(45.67 g/L biomass&19.16 g/L lipid).Moreover,the intermittent sludge feeding strategy significantly reduced foaming and requirement of anti-foam during fermentation when compared to control strategy.The energy balance of biodiesel production from lipid obtained by intermittent sludge feeding strategy(30 g/L SS)was energeti-cally favorable.It was also revealed from yield coefficients and energy balance that sludge had an important contribution in microbial lipid and biodiesel production.