Browsing by Author "Raval, R."

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A marine chitinase from Bacillus aryabhattai with antifungal activity and broad specificity toward crystalline chitin degradation
(Taylor and Francis Ltd., 2022) Subramani, A.K.; Raval, R.; Sundareshan, S.; Sivasengh, R.; Raval, K.
Chitinases convert chitin into chitin oligomers and are also known antifungal agents. Chitin oligomers have numerous industrial applications. However, chitin’s crystalline nature requires pretreatment before breakdown into oligomers. In the study, a novel marine bacterium Bacillus aryabhattai is isolated from the Arabian Sea. Bacterial growth in different crystalline chitin substrates like chitin powder, chitin flakes, and colloidal chitin confirmed the chitinase presence in bacterium could act upon insoluble crystalline chitin with the fractional release of oligomers. The domain architecture analysis of the chitinase confirmed the presence of two N-terminal LysM domains which help enzyme action on crystalline chitin. Statistical optimization of media and Process parameters revealed glycerol, yeast extract, magnesium chloride, and manganese sulfate as significant media components along with colloidal chitin. The optimum process parameters such as pH 7, temperature 40 °C, inoculum size 12.5% (v/v), and inoculum age 20 hours enhanced the specific enzyme activity to ±146.2 U/mL, ±114.9 U/mL and ±175.4 U/mL against chitin powder, chitin flakes and colloidal chitin respectively, which is five to six times higher than basal level activity. The antifungal activity of chitinase against plant pathogenic fungi like Candida albicans and Fusarium oxysporum revealed a zone of inhibition with 14 mm diameter. © 2022 Taylor & Francis Group, LLC.
A perspective of advanced biosensors for environmental monitoring
(Elsevier, 2019) Mohan Balakrishnan, R.M.; Uddandarao, U.; Raval, K.; Raval, R.
Biosensor technology has developed in leaps and bounds due to multidisciplinary approach between biotechnology and nanotechnology. This synergy provided much needed characteristic features, such as sensitivity and selectivity to the biosensor technology. Biosensors are venerated as superior entities for electrochemical, optical, and calorimetric-based sensing because of their exceptional size properties. They are the potential tools, which exhibited the feasibility and potential in detecting various biological, physical, chemical, radiological contaminants in water. This book chapter outlines the overview of various types of sensors, especially on chalcogen-based semiconductor nanoparticles. In this scenario, green route nanoparticles which employ PbSe quantum dots synthesis via marine Aspergillus terreus and ZnS/PbS nanoparticles via an endophytic fungus Aspergillus flavus are focused in this chapter. The book chapter also discusses about highly selective biogenic nanosensors which play a significant role in improving the capacity of biosensors due to their size tuneable quantum confinement effects. Potential applications of these biosensors for environmental monitoring are discussed. © 2019 Elsevier Inc. All rights reserved.
A sustainable bioprocess for lipase production using seawater and the byproduct obtained from coconut oil industries
(CRC Press/Balkema, 2019) Raval, R.; Verma, A.; Raval, K.
Globally lipases are the most attractive source of research, as it has numerous applications in various industries like food industry, paper and pulp industry, preparation of beverages etc. A lipase producing bacterium, Pseudomonas stutzeri, was isolated from sea water. The bacterial culture was introduced to the physical and chemical mutagens and then allowed to grow on the solid media. A number of mutated clones were produced which were further followed by examining their lipase activity. There was a significant increase in the extracellular lipase activity i.e. 13, 56 and 14 folds increase in the case of UV mutation, sodium azide, and NTG respectively. Further, the mutants were subcultured and stability was observed in NTG mutants. The lipase production from the NTG mutants was optimized using Response Surface Methodology (RSM). The maximum lipase activity of 1132.6 U/ml was obtained which was about 7 folds higher than the parent strain using the process which utilized the residual coconut cake, a byprtoduct of coconut oil industries and the sea water which makes the process sustainable. Â© 2020 Taylor & Francis Group, London, ISBN 978-0-367-33737-7
Bioethanol: A New Synergy between Marine Chitinases from Bacillus haynesii and Ethanol Production by Mucor circinelloides
(MDPI, 2023) Govindaraj, V.; Subramani, A.K.; Gopalakrishnan, R.; Kim, S.-K.; Raval, R.; Raval, K.
The fourth generation of bioethanol production is on a lookout for non-lignocellulosic biomass waste. One such candidate is chitin, the second most abundant biopolymer on earth. However, the crystalline nature of chitin hinders its application potential for bioethanol production. This limitation can be circumvented by hydrolysing this polymer into oligomers using chitinases. We used this hypothesis and isolated a Bacillus haynesii, a marine bacterium that utilizes colloidal chitin as a substrate and produces chitin oligosaccharides. Further, we utilized Mucor circinelloides to produce bioethanol using the chitin oligosaccharides in the shake flask. We investigated the effect of inoculum age, filling volume, different substrates, and substrate concentration on bioethanol production using Mucor circinelloides from Bacillus haynesii-produced chitin oligosaccharides. Bacillus haynesii demonstrated a maximum chitinase activity of 3.08 U/mL with specific activity of 96 U/mg at the 90th h. Chitin oligosaccharides produced by Bacillus haynesii were confirmed using mass spectrometry. Bioethanol concentration was determined using dichromate oxidation assay as well as gas chromatography. The research resulted in 7.4 g/L of ethanol from 30 g/L of chitin oligosaccharides, with a maximum ethanol yield of 0.25 g of ethanol/g substrate at the 55th h with 48 h inoculum in 80 mL of fermentation medium. Results suggest that chitin oligosaccharides from Bacillus haynesii are an effective and renewable substrate for bioethanol production. © 2023 by the authors.
Cloning, expression, purification and characterization of chitin deacetylase extremozyme from halophilic Bacillus aryabhattai B8W22
(Springer Science and Business Media Deutschland GmbH, 2021) Pawaskar, G.M.; Raval, K.; Rohit, P.; Shenoy, R.P.; Raval, R.
Chitin deacetylase (CDA) (EC 3.5.1.41) is a hydrolytic enzyme that belongs to carbohydrate esterase family 4 as per the CAZY database. The CDA enzyme deacetylates chitin into chitosan. As the marine ecosystem is a rich source of chitin, it would also hold the unexplored extremophiles. In this study, an organism was isolated from 40 m sea sediment under halophilic condition and identified as Bacillus aryabhattai B8W22 by 16S rRNA sequencing. The CDA gene from the isolate was cloned and overexpressed in E. coli Rosetta pLysS and purified using a Ni–NTA affinity chromatography. The enzyme was found active on both ethylene glycol chitin (EGC) and chitooligosaccharides (COS). The enzyme characterization study revealed, maximum enzyme velocity at one hour, optimum pH at 7 with 50 mM Tris–HCl buffer, optimum reaction temperature of 30 ºC in standard assay conditions. The co-factor screening affirmed enhancement in the enzyme activity by 142.43 ± 7.13% and 146.88 ± 4.09% with substrate EGC and COS, respectively, in the presence of 2 mM Mg2+. This activity was decreased with the inclusion of EDTA and acetate in the assay solutions. The enzyme was found to be halotolerant; the relative activity increased to 116.98 ± 3.87% and 118.70 ± 0.98% with EGC and COS as substrates in the presence of 1 M NaCl. The enzyme also demonstrated thermo-stability, retaining 87.27 ± 2.85% and 94.08 ± 0.92% activity with substrate EGC and COS, respectively, upon treatment at 50 ºC for 24 h. The kinetic parameters Km, Vmax, and Kcat were 3.06E?05 µg mL?1, 3.06E + 01 µM mg?1 min?1 and 3.27E + 04 s?1, respectively, with EGC as the substrate and 7.14E?07 µg mL?1, 7.14E + 01 µM mg?1 min?1 and 1.40E + 06 s?1, respectively, with COS as the substrate. The enzyme was found to be following Michaelis–Menten kinetics with both the polymeric and oligomeric substrates. In recent years, enzymatic conversion of chitosan is gaining importance due to its known pattern of deacetylation and reproducibility. Thus, this BaCDA extremozyme could be used for industrial production of chitosan polymer as well as chitosan oligosaccharides for biomedical application. © 2021, The Author(s).
Engineering a recombinant chitinase from the marine bacterium Bacillus aryabhattai with targeted activity on insoluble crystalline chitin for chitin oligomer production
(Elsevier B.V., 2024) Subramani, A.K.; Ramachandra, R.; Thote, S.; Govindaraj, V.; Vanzara, P.; Raval, R.; Raval, K.
Chitin, an abundant polysaccharide in India, is primary by-product of the seafood industry. Efficiently converting chitin into valuable products is crucial. Chitinase, transforms chitin into chitin oligomers, holds significant industrial potential. However, the crystalline and insoluble nature of chitin makes the conversion process challenging. In this study, a recombinant chitinase from marine bacteria Bacillus aryabhattai was developed. This enzyme exhibits activity against insoluble chitin substrates, chitin powder and flakes. The chitinase gene was cloned into the pET 23a plasmid and transformed into E. coli Rosetta pLysS. IPTG induction was employed to express chitinase, and purification using Ni-NTA affinity chromatography. Optimal chitinase activity against colloidal chitin was observed in Tris buffer at pH 8, temperature 55°C, with the presence of 400 mM sodium chloride. Enzyme kinetics studies revealed a Vmax of 2000 μmole min−1 and a Km of 4.6 mg mL−1. The highest chitinase activity against insoluble chitin powder and flakes reached 875 U mg−1 and 625 U mg−1, respectively. The chitinase demonstrated inhibition of Candida albicans, Fusarium solani, and Penicillium chrysogenum growth. Thin Layer Chromatography (TLC) and LC-MS analysis confirmed the production of chitin oligomers, chitin trimer, tetramer, pentamer, and hexamer, from chitin powder and flakes using recombinant chitinase. © 2024 Elsevier B.V.
Enhanced degradation of azo dye using mixed cultures of white-rot fungi in a modified rotating packed disc bioreactor and reuse of treated water
(Elsevier Ltd, 2023) Kalnake, R.P.; Raval, R.; Murthy, D.V.R.; Vanzara, P.B.; Raval, K.
Reactive azo dyes are toxic and carcinogenic. In this study, mixed cultures of white-rot fungi (WRF) are used to treat synthetic reactive black 5 (RB-5) wastewater in a modified rotating packed disc bioreactor (RPDB). The continuous degradation studies were carried out for 25 days under the influence of the recycle stream in which 3665 L of synthetic effluent was treated. The dye wastewater was completely decolorized with more than 93 % chemical oxygen demand (COD) reduction using the mixed fungal culture. During the continuous operation, the COD of influent reduced more than 85 % for successive 25 days of continuous operation at hydraulic retention time of 10.8 h. The dry biomass loading was about 0.14 g/g GAC at the end of the continuous process. The rate of COD removal followed first order kinetics with a rate constant of 0.026 per hour. The treated water was reused to produce melanin from microbial culture. © 2023 Elsevier Ltd
Evaluation of Chitosan and Its Derivatives in Immunomodulating Blood Sentinel Cells
(Apple Academic Press, 2024) Subramani, A.K.; Raval, K.; Raval, R.
Opportunistic pathogens can invade and thus cause infections in the body. However, in most instances, the body mounts an immune response to counter the infection. Sentinel cells are the body’s second line of defense, which act against invading microbes. An important part of the innate system, these sentinel cells include macrophages, neutrophils, and dendritic cells. The plethora of pattern recognition receptors helps them to combat the invading pathogen from colonizing the body. They do so by inducing inflammation and oxidative stress or by the adaptive immune cells releasing chemokines. However, a paradigm shift of unrestrained inflammation or oxidative stress can also lead to a hypersensitivity reaction, sepsis, or autoimmune disorder. On the other extreme, an under-responsive sentinel cell might lead to frequent infections. Immunomodulators like chitosan can assist the sentinel cells in the titrated priming of the pathogen, thereby reducing chronic inflammation conditions. Chitosan, the amorphous derivative of chitin is the second largest abundant polymer after cellulose. The physicochemical properties of chitosan and COS depend on molecular weight, degree of polymerization 52(DP), and degree of deacetylation (DD). Thus, the modulation of these properties can impart chitosan and its oligosaccharides (COS) for various biomedical applications. In the present chapter, an overview of the innate responses of the sentinel cells and the synergistic roles played by chitosan and its derivatives to regularize various responses. © 2024 Apple Academic Press, Inc.
Expression of Bacillus licheniformis chitin deacetylase in E. coli pLysS: Sustainable production, purification and characterisation
(2019) Bhat, P.; Pawaskar, G.-M.; Raval, R.; Cord-Landwehr, S.; Moerschbacher, B.; Raval, K.
Chitosan obtained by enzymatic deacetylation of chitin using chitin deacetylase (CDA) holds promise primarily due to the possibility to yield chitosan with non-random patterns of acetylation and more environmentally friendly process compared to chemical deacetylation. In the present study, a sustainable bioprocess is reported for over-expression of a bacterial CDA in E. coli pLysS cells. A Bacillus licheniformis CDA gene is identified in the genome of the bacterium, cloned, and expressed, yielding enzymatically active recombinant protein. For enzyme production, a growth medium is formulated using carbon and nitrogen sources, which do not compete with the human food chain. The maximum enzyme activity of 320 20 U/mL is achieved under optimized conditions. The CDA productivity is improved by about 23 times in shake flask culture by optimizing operating conditions and medium components. The CDA is purified and the enzyme kinetic values i.e. K m , V max and K cat are reported. Also the effect of cofactors, temperature, and pH on the enzyme activity is reported. Further, economic yield is proposed for production of CDA through this bioprocess. 2019 Elsevier B.V.
Expression of Bacillus licheniformis chitin deacetylase in E. coli pLysS: Sustainable production, purification and characterisation
(Elsevier B.V., 2019) Bhat, P.; Pawaskar, G.-M.; Raval, R.; Cord-Landwehr, S.; Moerschbacher, B.; Raval, K.
Chitosan obtained by enzymatic deacetylation of chitin using chitin deacetylase (CDA) holds promise primarily due to the possibility to yield chitosan with non-random patterns of acetylation and more environmentally friendly process compared to chemical deacetylation. In the present study, a sustainable bioprocess is reported for over-expression of a bacterial CDA in E. coli pLysS cells. A Bacillus licheniformis CDA gene is identified in the genome of the bacterium, cloned, and expressed, yielding enzymatically active recombinant protein. For enzyme production, a growth medium is formulated using carbon and nitrogen sources, which do not compete with the human food chain. The maximum enzyme activity of 320 ± 20 U/mL is achieved under optimized conditions. The CDA productivity is improved by about 23 times in shake flask culture by optimizing operating conditions and medium components. The CDA is purified and the enzyme kinetic values i.e. Km, Vmax and Kcat are reported. Also the effect of cofactors, temperature, and pH on the enzyme activity is reported. Further, economic yield is proposed for production of CDA through this bioprocess. © 2019 Elsevier B.V.
Expression studies of Bacillus licheniformis chitin deacetylase in E. coli Rosetta cells
(2017) Raval, R.; Simsa, R.; Raval, K.
Chitin, the biopolymer of the N-acetylglucosamine, is the most abundant biopolymer on the planet after cellulose. However owing to its crystalline nature, its deacetylated derivative; chitosan is industrially more potent. This conversion on an enzymatic scale can be made using chitin deacetylase. The metagenomics library constructed from the soil exposed to chitin and chitosan yielded chitin modifying enzymes, one of them being chitin deacetylase (CDA) utilized for the present study. The gene was amplified and expressed using the pET 22b vector in E. coli Rosetta cells. The effect of two additives; chitin and glycerol on the CDA activity were studied. The inclusion of glycerol in the medium improved the biomass by 50% from the initial value of 1.25 g/l to 2.5 g/l. The activity of CDA increased from 90 ?mol/min/ml to 343 ?mol/min/ml. The CDA activity reported in the present paper is the highest observed for any strain. The addition of glycerol to the media not only helped improve the yield of the chitin deacetylase but also imparted value addition to the waste of the biofuel industry. 2017 Elsevier B.V.
Expression studies of Bacillus licheniformis chitin deacetylase in E. coli Rosetta cells
(Elsevier B.V., 2017) Raval, R.; Simsa, R.; Raval, K.
Chitin, the biopolymer of the N-acetylglucosamine, is the most abundant biopolymer on the planet after cellulose. However owing to its crystalline nature, its deacetylated derivative; chitosan is industrially more potent. This conversion on an enzymatic scale can be made using chitin deacetylase. The metagenomics library constructed from the soil exposed to chitin and chitosan yielded chitin modifying enzymes, one of them being chitin deacetylase (CDA) utilized for the present study. The gene was amplified and expressed using the pET 22b vector in E. coli Rosetta cells. The effect of two additives; chitin and glycerol on the CDA activity were studied. The inclusion of glycerol in the medium improved the biomass by 50% from the initial value of 1.25 g/l to 2.5 g/l. The activity of CDA increased from 90 ?mol/min/ml to 343 ?mol/min/ml. The CDA activity reported in the present paper is the highest observed for any strain. The addition of glycerol to the media not only helped improve the yield of the chitin deacetylase but also imparted value addition to the waste of the biofuel industry. © 2017 Elsevier B.V.
Identification and characterization of chitinase producing marine microorganism: Unleashing the potential of chitooligosaccharides for bioethanol synthesis
(Elsevier B.V., 2024) Atheena, P.V.; Rajesh, K.M.; Raval, K.; Subbalaxmi, S.; Raval, R.
The dwindling supply of the petroleum product and its carbon footprint has initiated search for a sustainable fuel and alternate feed-stocks. One such underexplored feedstock is chitin, a waste derived from sea food processing. The limitation of insolubility and crystallinity inherent in chitin is addressed with the chitin hydrolysates. In the present study, a chitinases producing marine isolate was isolated from the sediments of Arabian Sea from a depth of 20 m. In order to increase the expression of the chitinases, sequential optimisation using one factor at a time and Taguchi experimental designs were employed which resulted in a yield of 13.46 U/mL which was 2.62 fold higher than the initial bioprocess condition values. In a two-step refinery protocol, Candida albicans was evolved towards chitooligosaccharides using chemically synthesized hydrolysates. In a fed –batch fermentation design the Candida yielded a 12.8 % conversion of these commercial chitin oligosaccharides into bioethanol in a run time of 48 h. This is the first report demonstrating the potential of Candida to utilise chitin oligosaccharides for the production of bioethanol. © 2024 The Author(s)
Identification, purification and functional characterization of a thermostable marine chitinase for potential fungal control via chitin degradation mechanism
(Elsevier Ltd, 2025) Atheena, P.V.; Raval, K.; Raval, R.
The growing prevalence of treatment-resistant Candida species highlights an urgent need for innovative antifungal therapies. The current range of antifungals, limited to polyenes, azoles, and echinocandins, are becoming insufficient due to the rise of resistance, including cross-resistance among fungal strains. Marine environment is an underexplored reservoir of unique enzymes which can be extremophilic. This study presents the cloning and expression of a chitinase gene from the bacterium Bacillus thuringiensis (BtChi), expressed in an E. coli system, yielding a protein with a molecular weight of approximately 71 kDa. Disc diffusion and MIC experiments indicated that 5 ?g/mL chitinase efficiently suppressed the growth of Candida albicans. Initial characterization identified the optimal activity at 40 °C and pH 7.0. The enzyme retained over 75 % activity across a pH range of 4–8 and a temperature range of 30–70 °C after 120 min. Activity was further enhanced by 24 % with 100 mM Na+. Kinetic parameters with colloidal chitin revealed Km and Vmax values to be 0.05 mg/mL and 1.37 U/mL respectively. This study holds the potential of developing a potent natural anti-fungal against the present day chemical counterparts. © 2025 The Authors
Immunomodulatory effects of chitooligosaccharides
(Springer International Publishing, 2022) Govindaraj, V.; Raval, K.; Raval, R.
Chitooligosaccharide, a low molecular weight, biodegradable and biocompatible polysaccharide possess various biological properties such as antimicrobial, antioxidant, wound healing effects. Immunomodulation is one of the attractive features of chitooligosaccharide and it is being explored in recent years. Chitooligosaccharide acts on various signaling molecules involved in immune response to elicit the required immune stimulation or immune suppression. In-vitro and in-vivo studies provide us great insight on biological activities of chitooligosaccharides underpinning the immunomodulatory effects. Overview of innate and adaptive immunity and immunomodulation effects of chitooligosaccharide is explored in this chapter while highlighting synthesis and biological activities of chitooligosaccharides. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022. All rights reserved.
Marine Bacillus haynesii chitinase: Purification, characterization and antifungal potential for sustainable chitin bioconversion
(Elsevier Ltd, 2024) Govindaraj, V.; Kim, S.-K.; Raval, R.; Raval, K.
The development of chitinase tailored for the bioconversion of chitin to chitin oligosaccharides has attracted significant attention due to its potential to alleviate environmental pollution associated with chemical conversion processes. In this present investigation, we purified extracellular chitinase derived from marine Bacillus haynesii to homogeneity and subsequently characterized it. The molecular weight of BhChi was approximately 35 kDa. BhChi displayed its peak catalytic activity at pH 6.0, with an optimal temperature of 37 °C. It exhibited stability across a pH range of 6.0–9.0. In addition, BhChi showed activation in the presence of Mn2+ with the improved activity of 105 U mL−1. Ca2+ and Fe2+ metal ions did not have any significant impact on enzyme activity. Under the optimized enzymatic conditions, there was a notable enhancement in catalytic activity on colloidal chitin with Km of 0.01 mg mL−1 and Vmax of 5.75 mmol min−1. Kcat and catalytic efficiency were measured at 1.91 s−1 and 191 mL mg−1 s−1, respectively. The product profiling of BhChi using thin layer chromatography and Mass spectrometric techniques hinted an exochitinase mode of action with chitobiose and N-Acetyl glucosamine as the products. This study represents the first report on an exochitinase from Bacillus haynesii. Furthermore, the chitinase showcased promising antifungal properties against key pathogens, Fusarium oxysporum and Penicillium chrysogenum, reinforcing its potential as a potent biocontrol agent. © 2024
Marine chitinase AfChi: green defense management against Colletotrichum gloeosporioides and anthracnose
(Springer Science and Business Media Deutschland GmbH, 2024) Rajesh, R.; Raval, K.; Raval, R.
Anthracnose disease, caused by the Colletotrichum gloeosporioides species, affects vegetables, fruits, pulses, and cereals, leading to significant economic losses worldwide. Although many synthetic fungicides are used to control this pathogen, eco-friendly biological alternatives are gaining popularity. This study focuses on isolating and purifying chitinase (Af Chi)from a marine bacterium and testing its antifungal efficacy against C. gloeosporioides spore germination by targeting the chitin in the fungal cell wall. The chitinase was purified from a marine bacterium A. faecalis from the Arabian Sea and had a molecular mass of 45 kDa and a specific activity of 84.6 U/mg. Af Chi worked best at 50 °C and pH 7.0 in Tris HCl buffer. Na+ ion was the highest cofactor, highlighting the halophilic nature of this chitinase. K+, Ca2+, Cu2+, Mg2+, Mn2+, and EDTA also increased activity, while Fe3+, Zn2+, Co2+, and Pb2+ decreased it. The Km and Vmax values were 1.87 µg/mL and 17.45 U/mL, respectively. Purified Af Chi at 10 mg/mL completely inhibited spore germination within 8 h and reduced the size of the spores. © The Author(s) 2024.
Microbes and their products as sensors in industrially important fermentations
(wiley, 2018) Raval, R.; Raval, K.
This chapter details on the different microbial sensors used in fermentations. It takes through the path in history dealing with the developments made in devicing various sensors and their applications in as industrially important products. The chapter is designed to re-analyze the previous studies that covered the usage of whole cell and products of microbes as important parameters to improve the fermentation processes. © 2019 John Wiley & Sons Ltd. All rights reserved.
Photobioreactors for wastewater treatment: Recent advances
(Nova Science Publishers, Inc., 2017) Lavanya, A.; Raval, K.; Raval, R.
Sustainability of any waste treatment process depends on how a waste, particularly wastewater, is handled. Wastewater treatment is greatly important for the welfare of the environment and of the Earth in general. An integrative approach involving CO2 sequestration, effluent treatment and biomass generation presents a tremendous potential as the overall process in wastewater treatment and is more sustainable compared with conventional treatment. Research on the use of photobioreactors (PBRs) in wastewater treatment has gained momentum in the past decade. The use of photosynthetic microorganisms, such as microalgae and cyanobacteria, in wastewater treatment offers advantages, such as low energy requirement, biomass production and CO2sequestration. A large amount of inorganic species present in wastewater promotes the growth of various photosynthetic microorganisms. Removal of high concentrations of inorganic compounds is the major requisite in any wastewater treatment process. Some photosynthetic organisms, especially microalgae, play an important role in a treatment process that involves reduction of nitrates, phosphates and sulfates. Literature suggests that the use of PBRs in wastewater treatment considerably reduces the cost of microalgal cultivation and consequently controls water pollution, conserves freshwater resources and produces useful chemicals and biomass. This chapter focuses on research advances in wastewater treatment using PBRs. Different types of wastewater handled, mixed culture systems (e.g., algal.bacterial system employed in wastewater treatment), types of PBRs used, and bottlenecks that must be addressed to scale-up the wastewater treatment process are discussed. © 2017 by Nova Science Publishers, Inc. All rights reserved.
Process optimisation for improved chitinase production from marine isolate Bacillus haynesii and bioethanol production with Saccharomyces cerevisiae
(Springer Nature, 2025) Govindaraj, V.; Anandan, D.K.; Kim, S.-K.; Raval, R.; Raval, K.
In the quest for sustainable fuel sources, chitin-based biorefineries are gaining recognition as chitin is the second most abundant bioresource after cellulose. This approach not only provides an effective method for converting shell waste from seafood processing into valuable bioethanol but also helps in waste management. In this study, Bacillus haynesii, a marine isolate, was investigated and this is the first report on optimisation of process parameters for chitinase production from Bacillus haynesii. The One Factor at a Time (OFAT) method was used to optimize process parameters including inoculum age, inoculum size, temperature, pH, and filling volume, with colloidal chitin identified as the best carbon source for the growth of Bacillus haynesii. The Plackett-Burman Design (PBD) was employed to screen media components, followed by optimization using the Taguchi Orthogonal Array method. The media components investigated included glycerol, yeast extract, MnCl2·4H2O, MgSO4·7H2O, NH4Cl, and colloidal chitin. As a result, the optimized media—comprising 7.5 g/L yeast extract, 7.5% (w/v) glycerol, 0.6% (w/v) colloidal chitin, 1.44 g/L MnCl2·4H2O, and 1.2 g/L MgSO4·7H2O—yielded an enzyme activity of 6.85 U/mL with a specific activity of 28.87 U/mg. Furthermore, ethanol production from chitin oligosaccharides by Saccharomyces cerevisiae was quantified using the potassium dichromate oxidation method, achieving a bioethanol concentration of 2.48% v/v from 33.18 g/L of chitin oligosaccharides. These results demonstrate the potential of Bacillus haynesii-derived chitin oligosaccharides as a promising substrate for bioethanol production. © The Author(s) 2025.