Enhancement of protease production by the optimization of Bacillus subtilis culture medium.

Aims: Traditionally, crustacean wastes have been managed by using acid and alkali which leads to major environmental issue. However, over the recent years microbial fermentation has gained its way whereby producing similar effects as chemical treatment and a higher quality product can be obtained. Extracellular protease from Bacillus subtilis was used further by optimizing its culture medium to enhance protease production. Methodology and Results: The culture media was optimized with 4 various sources; Shrimp Crab Shell Powder (SCSP), nitrogen sources, inorganic salts, and carbon sources. It was found that culture media supplemented with 9% SCSP, 3% yeast extract, 1% sodium chloride and 9% glucose augmented protease activity up to 565.80 ± 19.41 U/mL compared to the un-optimized media (170.57 ± 6.75 U/mL). By using this optimized media, the ability and efficiency of B. subtilis in a period of 6 days was investigated whereby acid treated shrimp shells (ATSS) and raw shrimp shell powder (RSSP) were used in substitution of SCSP. In a period of 6 days, the protein content in both ATSS and RSSP was found to have been removed up to 60% and 42% respectively. However deproteinization was found to be more efficient in RSSP with the ratio of tyrosine to protein remained constantly high throughout the 6 days period. Conclusion, significance and impact of study: A better, more efficient and environmental friendly method is continuously being improvised to manage shrimp wastes with the use of microbes

Enhance desilication and delignification in paddy straw via chemical and physical pretreatment

Paddy straw is one of the most common agricultural wastes and renewable resources available in Malaysia containing lignocellulosic values. Large parts of these plant materials are made up of complex carbohydrates such as cellulose and hemicelluloses which can be converted to fermentable sugars. In fermentation process of sugars, ethanol can be produce as by-product with the help of aerobic microorganism. However, the presence of high ash and silica content in paddy straw makes it an inferior feedstock for ethanol production. The objective of this study is set to determine the best physical and chemical pretreatment for desilication of paddy straw and encouraged delignification process. The pretreatment comprises the combination of physical and chemical treatments to maximize the process of desilication and delignification in the paddy straw. Physical treatment begins with paddy straws cut and grind to three different sizes which were 2 mm, 5 mm and 8 mm. All different sizes of paddy straw was (i) autoclave, (ii) boiled and (iii) soaked in four different concentrations (0.5%, 1%, 2% and 5%) of nitric acid and sodium hydroxide, respectively for chemical treatment. With the comparison on dry matter basis to untreated paddy straw, 5mm paddy straw pretreated with 0.5% nitric acid showed the highest cellulose content (96.6%). Through this combination, the cellulose fragment was improved by 54% but the lignin and hemicellulose were reduce to 38% and 54%, compared to untreated paddy straw, respectively. The percentage of ash content in acid treatment have total increment of 56% compared to untreated samples content while the percentage of ash content for alkali treatment have total loss of 55% and reduced compared to untreated samples. Therefore, 0.5% nitric acid was found to be the most suitable condition to break the cellulose-lignin complex

Toxicity of Bacillus thuringiensis biopesticide produced in shrimp pond sludge as alternative culture medium against Bactrocera dorsalis (Hendel)

Among entomopathogenic bacteria, Bacillus thuringiensis (Bt) has been widely used to replace the conventional chemical pesticides to control insect pets. However, their application is limited due to high production cost through fermentation. In this study, shrimp pond sludge was used as an alternate culture medium for Bt ATCC10792. The sludge was used under three different preparations; (i) without pre-treatment, (ii) with acid treatment (hydrolysed sludge) and (iii) the supernatant obtained after the centrifugation of the hydrolysed sludge. Bacterial growth rate and sporulation were evaluated throughout the fermentation. The highest growth rate and sporulation were observed in hydrolysed sludge with 7.44x106±5.16 CFU/ml and 5.90x106±7.88 CFU/ml, respectively. Bioassay of entomotoxicity test was also carried out on the fruit fly larva, Bactrocera dorsalis (Hendel) and 81.2% mortality was observed. A significant deterioration was observed in larval weight and size. Larval pupation was also reduced in size where treated pupa was 30% smaller than the control and therefore lowering the adult fly emergence rate. Emerged adult fruit fly showed physical deterioration on the morphology (undeveloped, crumpled wings and cranked abdomen) and significantly affecting the survival rate of the flies. This study has proven the potential of shrimp pond sludge to be used as an alternate culture medium for Bt-based biopesticides production

Identification of bioactive compounds produced by bacteria-based biopesticides, Bacillus thuringiensis ATCC 10792 produced in shrimp pond sludge

Biological controls of destructive pest in forest and agriculture sector using bacteria were proven to minimize the problems caused by the usage of chemical insecticides. However, their application is limited due to high production cost through fermentation. In this study, shrimp pond sludge and wastewater were used as an alternate culture medium for bacteria-based biopesticides production. It has been determined by previous part of this study that Bacillus thuringiensis ATCC 10792 in hydrolysed shrimp pond has showed the highest potential to be used as bacteria-based biopestecides based on their high growth rate (7.44x106 ± 5.16 CFU/ml) and sporulation (5.90x106 ± 7.88 CFU/ml). Bioassay of entomotoxicity also showed high mortality rate, disruption on the target insect physically and affect the life cycle of the target insect. Hence, proteomic analysis using SDS-Page and MALDITOF-MS were conducted to identify the bioactive compound that contribute to the toxicity of the bacteria-based biopesticides produced. Separation and identification of the bioactive components produced by the bacteria during the fermentation were done and two types of protein were produced by the bacteria. Superoxide dismustase and spore coat protein were identified to be produced during the fermentation and respectively play an important roles to the toxicity of the bacteria. This study showed the potential of Bt ATCC10792 to be used as biopesticides

Evaluation of pH and temperature effects on mycoremediation of phenanthrene by Trichoderma sp.

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous persistent organic contaminants found in the environment most of which are toxic, mutagenic, teratogenic and carcinogenic. For an effective bioremediation of PAHs using micro-organisms, optimum environmental conditions needs to be in place for degradation to occur. The aim of this study was to investigate the effect of physical factors such as pH and temperature on phenanthrene degradation by a sediment fungal isolate Trichoderma sp. SY1 using liquid Mineral Salt Broth (MSB). Both parameters; temperature and pH was observed to significantly affect the strains ability to degrade phenanthrene. Maximum phenanthrene degradations was achieved at a temperature of 35°C and a neutral pH of 7 where degradation efficiencies of 69.5% and 76.8% were achieved respectively with a corresponding high biomass accumulation of 62mg and 48mg dry weight at same temperature and pH points. Lower phenanthrene degradations and fungal growth were observed at lower and higher temperatures. It can be concluded that an optimum pH of 35°C and pH of 7 best supports the strains ability to degrade phenanthrene and should most likely be applied in the microbial PAHs degradation, using this strain

The availability of astaxanthin from shrimp shell wastes through microbial fermentations, Aeromonas hydrophila and cell disruptions

The removal of chitin and protein is crucial for the extraction of astaxanthin from shrimp shells. While the traditional method uses chemical extraction, the current study emphasises on the use of microbial enzyme, which is safer for the environment throughout the extraction process. Aeromonas hydrophila was isolated from shrimp shells and four types of sources were chosen; shrimp crab shell powder (SCSP), nitrogen sources, inorganic salts and carbon sources for the optimization of A. hydrophila culture media. Four types of cell disruption were introduced; autoclaving with distilled water, autolysis, heating and grinding with liquid nitrogen to further expose astaxanthin. The optimized culture media was found to be 7% SCSP, 9% bacto-peptone, 1% sodium chloride and 1% lactose at pH 7.0. This optimized media gave a high increment to both chitinase and protease activity from 0.092 and 60.816 U/mL to 1.164 and 272.565 U/mL, respectively. Mechanical cell disruptions using liquid nitrogen on pre-treated shrimp shells gave an astaxanthin recovery of 66% compared to the control. The availability of astaxanthin was made possible by the effects of optimization of the culture media in addition of mechanical cell disruptions