A nationwide screening program searching for microbial control agents of mosquitos was initiated in Malaysia in 1986. A total of 725 samples were collected and 2,394 bacterial colonies were isolated and screened for larvicidal activity. From such screening, 20 Bacillus thuringiensis, 6 B. sphaericus, 1 Clostridium bifermentans and 2 Pseudomonas pseudomallei larvicidal isolates were obtained. Of these, a new B. thuringiensis named as subspecies malaysianensis was found, while the C. bifermentans was also a new anaerobe individualized as serovar malaysia. It was concluded that this screening program was highly successful.
Evaluation of the effectiveness of Bacillus thuringiensis ssp. israelensis (B.t.i.) against mosquito larvae dispersed by ultralow volume (ULV) spraying was conducted in simulated field trials. Effectiveness was measured using 3 different indicators: larval mortality, colony-forming unit enumeration, and droplet analysis. B.t.i. was dispersed with a ULV generator using 2 different flow rates: 0.3 and 0.5 liter/min on 2 different days. Based on the results of this study, it can be concluded that an output of 0.3 liter/min is effective for controlling Aedes aegypti. although a dosage of 0.5 liter/min can be used when high residual activity is desired. For Culex quinquefasciatus control, both dosages were effective but with low residual activity. For Anopheles maculatus control, only a discharge rate of 0.5 liter/min was effective with low residual activity. B.t.i. application at both dosages penetrated tires well, indicating that B.t.i. ULV application is an effective method for controlling container-inhabiting mosquitoes. Good coverage of target area and penetration were attributed to satisfactory droplet profiles.
Lipases are of great interest for different industrial applications due to their diversity and versatility. Among different lipases, microbial lipases are preferable due to their broad substrate specificity, and higher stability with lower production costs compared to the lipases from plants and animals. In the past, a vast number of bacterial species have been reported as potential lipases producers. In this study, the lipases-producing bacterial species were isolated from an oil spillage area in the conventional night market. Isolated species were identified as Bacillus species by biochemical tests which indicate their predominant establishment, and further screened on the agar solid surfaces using lipid and gelatin as the substrates. Out of the ten strains tested, four potential strains were subjected to comparison analysis of the lipolytic versus proteolytic activities. Strain 10 exhibited the highest lipolytic and proteolytic activity. In all the strains, the proteolytic activity is higher than the lipolytic activity except for strain 8, suggesting the possibility for substrate-based extracellular gene induction. The simultaneous secretion of both the lipase and protease is a mean of survival. The isolated bacterial species which harbour both lipase and protease enzymes could render potential industrial-based applications and solve environmental issues.
Matched MeSH terms: Bacillus/enzymology*; Bacillus/growth & development
The current experiment was conducted to evaluate and compare the efficacy of two different probiotics Bacillus subtilis WB60 and Lactobacillus plantarum KCTC3928 in diet of Japanese eel, Anguilla japonica. Seven experimental diets were formulated to contain no probiotics (CON), three graded levels of B. subtilis at 106 (BS1), 107 (BS2), 108 (BS3) and L. plantarum at 106 (LP1), 107 (LP2), 108 (LP3) CFU/g diet. Twenty fish averaging 8.29 ± 0.06 g were distributed in to 21 aquaria and were randomly assigned to one of the experimental diets in triplicate groups. Average weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) of fish fed B. subtilis at 107 (BS2) and 108 (BS3) CFU/g diet were significantly higher than those of fish fed other experimental diets (P
This study evaluated the synergistic effects of dietary Bacillus subtilis WB60 and mannanoligosaccharide (MOS) in juvenile Japanese eel, Anguilla japonica. Seven treatment diets were formulated to contain three different levels of B. subtilis (0.0, 0.5, and 1.0 × 107 CFU/g diet denoted as BS0, BS0.5, and BS1, respectively) with two MOS levels (0 and 5 g/kg diet denoted as M0 and M5, respectively), and one diet with oxytetracycline (OTC) at 5 g/kg diet. Each diet (BS0M0 (CON), BS0M5, BS0.5M0, BS0.5M5, BS1M0, BS1M5, and OTC) was fed to triplicate groups of 20 fish averaging 9.00 ± 0.11 g (mean ± SD) for eight weeks. Average weight gain, feed efficiency, specific growth rate and protein efficiency ratio of fish fed the BS0.5M5 and BS1M5 diets were significantly higher than those of fish fed CON, BS0.5M0 and OTC diets (P 0.05). Therefore, the results for growth performance, non-specific immune responses, intestinal morphology, and disease resistance demonstrated that supplementation of B. subtilis at 0.5 × 107 CFU/g diet and mannanoligosaccharide at 5 g/kg diet could have beneficial synergistic effects in Japanese eel. The isolated probiotic from eel and the selected prebiotic could lead to the development of a specific and potential synbiotic in Japanese eel aquaculture.
Susceptibility levels of a few laboratory-cultured and dengue-endemic area field-collected strains of Aedes aegypti and Aedes albopictus to Bacillus thuringiensis israelensis (Bti) at different storage ages were studied. The susceptibility of laboratory-cultured World Health Organization (WHO) Bora Bora reference, Vector Control Research Unit (VCRU), and Fumakilla Malaysia Berhad (FMB) strains of Ae. aegypti to Bti was examined. The sensitivity to Bti decreased with storage age. The median lethal concentration (LC50) for Bti increased by 2-3 times after 2 years compared to a fresh sample (3-6 months of storage). However, after the 2-year storage period, Bti still provided very good efficacy against all laboratory-cultured susceptible strains of Ae. aegypti and Ae. albopictus. The observed 95% lethal concentration values were about 20 times lower than the recommended concentration (6,000 international toxic units (ITU)/liter). Results obtained from the study against the dengue-endemic area field-collected strains of Ae. aegypti and Ae. albopictus confirmed the effectiveness of the Bti after storage for 2 years (18-24 months). For Ae. aegypti, the Ujung Batu strain was the most susceptible to Bti, whereas the Sungai Nibong strain showed the most tolerance. Susceptibility of laboratory-cultured strains varied; the Air Itam strain of Ae. albopictus was the most susceptible to Bti, whereas the Kampung Serani strain was the most tolerant among the field strains. However, the laboratory strain of Ae. albopictus was more susceptible than all the field strains.
Studies were carried out on the bioefficacy and residual activity of Bacillus thuringiensis israelensis H-14 (Bti) (water-dispersible granules of VectoBac ABG 6511 and liquid formulations of VectoBac 12AS) and pyriproxyfen (insect growth regulator, Sumilarv 0.5%) as direct applications for control of larvae of Aedes aegypti and Aedes albopictus. Two dosages of each Bti formulation (285 and 570 international toxic units [ITU]/liter) and the integration of both Bti formulations and pyriproxyfen were used for residual tests with 45-liter earthen jars for a period of 4 wk. In 1 test series, the treated water was replenished daily with 6 liters of seasoned untreated water. In the 2nd test series, the water in the jars was topped up to the 40-liter level during evaluation. Neither Bti formulation remained effective for a full week. Water-dispersible Bti granules provided effective initial control activity against Ae. aegypti and Ae. albopictus for both test designs (with replenishment and without replenishment of water). The higher dosage (570 ITU/liter) for both Bti formulations was only partially effective at the end of 1 wk after being diluted. After 1 wk, water-dispersible Bti granules provided greater larval mortality than did liquid Bti formulation against both mosquito species when integrated with pyriproxyfen. Pyriproxyfen (79.5 and 159 mg/liter) on its own showed low larvicidal activity but provided very effective control of adult emergence. In this study, integration of Bti (285 and 570 ITU/liter) with pyriproxyfen (79.5 mg/liter) extended the duration of partial larval control somewhat, but live larvae persisted throughout the 4-wk test. The integration effect was more obvious when water-dispersible Bti granules were integrated with pyriproxyfen than when liquid Bti was used. Integration of Bti with pyriproxyfen had a negative effect on adult emergence, which was completely inhibited by pyriproxyfen after day 1. Daily replenishment of water increased Bti activity and provided slightly better larval control. Aedes albopictus and Ae. aegypti were both completely susceptible to the higher concentration of Bti and pyriproxyfen in both test designs (with replenishment and without replenishment of water).
Studies were carried out on the residual efficacy of Bacillus thuringiensis H-14 (water dispersible granule, VectoBac ABG 6511) as direct application in the control of Aedes larvae in the field. Field Aedes sp populations in the earthen and glass jars were predetermined before initiation of the trial. On confirmation of the presence of Aedes species in the designated area, Sungai Nibong Kecil, Penang Island, Malaysia, Bti was introduced in the 55L earthen and 3L glass jars). Two test designs were carried out. The first design had treated water replenished daily with 6L of seasoned water and the second design is without the replenishment of water but evaporated water was replenished. Bti was effective in the field for at least 35 days with more than 80% reduction in the Aedes larvae in the treated containers. For earthen jars with daily replenishment of water, 100% reduction was recorded for the first 3 days, while more than 80% reduction was recorded up to day 40. At day 60, Bti still provided an efficacy of 54.32 +/- 4.61 (%) of reduction. Whilst for earthen jars without daily replenishment of water, 100% reduction was recorded for the first 5 days, while more than 80% of reduction was recorded up to day 40. For the glass jars studied, similar efficacy was observed. In jars with daily replenishment of water a better larval control was observed. Percentage of reduction from day 50 to 60 for replenishment of water was between 50 to 70% compared to without replenishment of water with less than 40%.
Laboratory efficacy and residual activity of a water dispersible granule formulation of Bacillus thuringiensis israelensis (Bti) at the dosages of 3000, 6000 and 15000 ITU/L were conducted in this study. The study was conducted in two different size containers, earthen jar (45 L) and glass jar (3 L) with or without daily replenishment of 6 L and 0.3 L of water in the earthen and glass jars, respectively. Results indicate that for both earthen jar and glass jar evaluations, Bti at the tested dosages, performed effectively against Aedes aegypti, giving a minimum of 42 days effective killing activity. When the dosage was increased from 3000 ITU/L to 6000 ITU/L or 15000 ITU/L, the effective periods of the Bti increased by an additional one to three weeks. The Bti water dispersible granule provided better larvicidal activity with replenishment of water compared with non-replenishment of water especially for the higher dosage (15000 ITU/L).
"Fried rice syndrome" originated from the first exposure to a fried rice dish contaminated with Bacillus cereus. This review compiles available data on the prevalence of B. cereus outbreak cases that occurred between 1984 and 2019. The outcome of B. cereus illness varies dramatically depending on the pathogenic strain encounter and the host's immune system. B. cereus causes a self-limiting, diarrheal illness caused by heat-resistant enterotoxin proteins, and an emetic illness caused by the deadly toxin named cereulide. The toxins together with their extrinsic factors are discussed. The possibility of more contamination of B. cereus in protein-rich food has also been shown. Therefore, the aim of this review is to summarize the available data, focusing mainly on B. cereus physiology as the causative agent for "fried rice syndrome." This review emphasizes the prevalence of B. cereus in starchy food contamination and outbreak cases reported, the virulence of both enterotoxins and emetic toxins produced, and the possibility of contaminated in protein-rich food. The impact of emetic or enterotoxin-producing B. cereus on public health cannot be neglected. Thus, it is essential to constantly monitor for B. cereus contamination during food handling and hygiene practices for food product preparation.
Bacillus cereus is a soil inhabitant gram positive bacterium, and is known to cause severe food poisoning. The objective of this study was to isolate and identify the presence of Bacillus cereus s.l. from selected ready to eat cereals purchased randomly from local supermarkets in Kuching and Kota Samarahan, Sarawak. The result showed that four of the 30 food samples were detected to be contaminated by B. cereus s.l. . Our findings suggested that it is important for the public to be aware of the safety of RTE cereals consumption, as it is possible that B. cereus s.l. may be present in high count number and pose hazardous health effects to the consumers.
The effects of methanolic extract of Javanese turmeric (Curcuma xanthorrhiza Roxb.) at different level of concentrations on the inactivation of Bacillus cereus, Escherichia coli, Pseudomonas spp. and Staphylococcus aureus in oyster mushroom (Pleurotus sajor-caju) were investigated. This study was conducted principally for the achievement on the best combination between the
susceptibility of C. xanthorrhiza extract on natural microflora and foodborne pathogenic bacteria with the sensory acceptability of the soaked oyster mushroom. Three different concentrations (g/ml), 0.05%, 0.50% and 5.00%, of C. xanthorrhiza extract prepared with dilution method were designed as sanitizing agent in treating the oyster mushroom at 5 minutes and 10 minutes.
There was significance reduction in the survival of microbial load between the untreated fresh oyster mushroom and those soaked with 0.05%, 0.50% and 5.00% rhizome extract (P
Quinoa (Chenopodium quinoa Willd.) is a highly nutritious food product with a comprehensive development prospect. Here, we discussed the effect of Bacillus amyloliquefaciens 11B91 on the growth, development and salt tolerance (salt concentrations: 0, 150, 300 mmol·L-1) of quinoa and highlighted a positive role for the application of plant growth-promoting rhizobacteria bacteria in quinoa. In this artical, the growth-promoting effect of Bacillus amyloliquefaciens 11B91 on quinoa (Longli No.1) and the changes in biomass, chlorophyll content, root activity and total phosphorus content under salt stress were measured. The results revealed that plants inoculated with 11B91 exhibited increased maximum shoot fresh weight (73.95%), root fresh weight (75.36%), root dry weight (136%), chlorophyll a (65.32%) contents and chlorophyll b (58.5%) contents, root activity (54.44%) and total phosphorus content (16.66%). Additionally, plants inoculated with 11B91 under salt stress plants showed significantly improved, fresh weight (107%), dry weight (133%), chlorophyll a (162%) contents and chlorophyll b (76.37%) contents, root activity (33.07%), and total phosphorus content (42.73%).
A Na(+)/H(+) antiporter gene was isolated from alkaliphilic Bacillus sp. G1. The full-length sequence of the Na(+)/H(+) antiporter gene was obtained using a genome walking method, and designated as g1-nhaC. An ORF preceded by a promoter-like sequence and a Shine-Dalgarno sequence, and followed by a terminator-like sequence was identified. The deduced amino acid sequence consists of 535 amino acids, and a calculated molecular mass of 57 776 Da. g1-nhaC was subsequently cloned into pET22b(+) and expressed in Escherichia coli BL21 (DE3). Recombinant E. coli harboring the g1-nhaC gene was able to grow in modified L medium at various concentrations of NaCl (0.2-2.0 M) at different pH values. The recombinant bacteria grew well in the medium with concentrations of NaCl as high as 1.75 M at pH 8.0-9.0. Minimal growth was observed at 2.0 M NaCl, pH 8.0-9.0. At pH 10, the recombinant bacteria grew well in a medium with a low concentration of NaCl (0.2 M). These results suggested that the g1-NhaC antiporter from Bacillus sp. G1 plays a role in Na(+) extrusion at lower pH values and in pH homeostasis at pH 10 under Na(+)-limiting conditions.
Acute Gastroenteritis (AGE) is common world wide and is a major health problem. The commonest cause is from contaminated water or food. Common infective agents are Rotavirus, Staph. aureus and Bacillus cereus. There was an AGE outbreak in Ipoh City from late August till early October 2006. Epidemiological and laboratory investigations were done. Fresh stool samples were taken from symptomatic patients. Water and food sampling were also done. Descriptive analysis of the outbreak was done. A total of 170 patients, mostly between 1 - 5 years of age, were affected. The highest incidents were seen in Bercham. Fever and diarrhea were the prominent features. Two stool samples (13.3%) were positive for E.coli and rotavirus respectively. Twelve of the twenty (60%) water samples taken were contaminated with coliform and fecal matter. Twenty-one of the eighty ((26.3%) food samples taken grew either E.coli, Staph. aureus or Bacillus cereus. It was concluded that a general source was responsible for this problem. The water supply to Ipoh City and the surrounding area is the most likely source. Novovirus was suspected as the organism involved because of the self-limiting and mild nature of the illness that occurred in this outbreak.
The AGE outbreak in Kinta District in September 2006 is due to contaminated
water supply from two water treatment
Chitin-encapsulated cadmium sulfide quantum dots (CdS@CTN QDs) were successfully synthesized from chitin and Cd(NO3)2 precursor using the colloidal chemistry method, toward the development of biocompatible and biodegradable QDs for biomedical applications. CdS@CTN QDs exhibited the nanocrystalline cubic CdS encapsulated by α-chitin. The average particle size of CdS@CTN QDs was estimated using empirical Henglein model to be 3.9 nm, while their crystallite size was predicted using Scherrer equation to be 4.3 nm, slightly larger compared to 3-mercaptopropionic acid-capped CdS QDs (3.2 and 3.6 nm, respectively). The mechanism of formation was interpreted based on the spectroscopic data and X-ray crystal structures of CdS@CTN QDs fabricated at different pH values and mass ratios of chitin to Cd(NO3)2 precursor. As an important step to explore potential biomolecular and biological applications of CdS@CTN QDs, their antibacterial activities were tested against four different bacterial strains; i.e. Escherichia coli, Bacillus subtillus, Staphylococcus aureus and Pseudomonas aeruginosa.
The development of nano-sized scaffolds with antibacterial properties that mimic the architecture of tissue is one of the challenges in tissue engineering. In this study, polycaprolactone (PCL) and PCL/gelatine (Ge) (70:30) nanofibrous scaffolds were fabricated using a less toxic and common solvent, formic acid and an electrospinning technique. Nanofibrous scaffolds were coated with silver (Ag) in different concentrations of silver nitrate (AgNO3) aqueous solution (1.25, 2.5, 5, and 10 %) by using dipping method, drying and followed by ultraviolet (UV) photoreduction. The PCL/Ge (70:30) nanofibrous scaffold had an average fibre diameter of 155.60 ± 41.13 nm. Characterization showed that Ag was physically entrapped in both the PCL and PCL/Ge (70:30) nanofibrous scaffolds. Ag(+) ions release study was performed and showed much lesser release amount than the maximum toxic concentration of Ag(+) ions in human cells. Both scaffolds were non-toxic to cells and demonstrated antibacterial effects towards Gram-positive Bacillus cereus (B. cereus) and Gram-negative Escherichia coli (E. coli). The Ag/PCL/Ge (70:30) nanofibrous scaffold has potential for tissue engineering as it can protect wounds from bacterial infection and promote tissue regeneration.
The outbreak of acute hepatopancreatic necrosis disease (AHPND) has caused great economic losses to the shrimp culture sector. However, the use of antibiotics to fight this disease has resulted in negative impacts on human health and the environment. Thus, the use of natural alternatives to antibiotics may be a better solution. In this study, four Bacillus species obtained from the guts of shrimps (Fenneropenaeus penicillatus and Penaeus monodon) showed antimicrobial activity against the AHPND-causing Vibrio parahaemolyticus strain 3HP using the cross-streaking and agar spot methods. Two of the Bacillus isolates, B2 and BT, also showed good probiotic properties, exhibiting tolerance to bile, good adhesion to shrimp mucus, non-hemolytic, susceptibility to antibiotics and being safe towards hosts. Moreover, a seaweed-probiotic blend (a combination of Bacillus B2 and 20 mg/ml of the red seaweed Gracilaria sp.) exhibited synergistic in vitro inhibition against V. parahaemolyticus strain 3HP, with an observed inhibition zone of 5.0 mm. The broth co-culture experiment results further indicated that the seaweed-probiotic blend inhibited V. parahaemolyticus through competitive exclusion. The in vivo challenge trials also confirmed that this seaweed-probiotic blend significantly reduced the mortality of shrimps post-challenge with the AHPND-causing V. parahaemolyticus strain 3HP (p < 0.05) compared to the negative control (mortality rate = 13.88% vs 72.19%). Thus, this seaweed-probiotic blend may serve as an alternative to antibiotics in controlling the outbreak of AHPND.
The sigma-E transcription factor (σETF) can be found in most of the bacteria cells including Bacillus thuringiensis. However, the cellular regulatory mechanisms of these transcription factors in the mass production of δ-endotoxins during sporulation stage are yet to be revealed. In addition, the recognition of DNA towards σETF DNA binding motifs that led to the transcription activities is also being poorly studied. Therefore, this work studied the possible DNA binding motifs of σETF by utilising in silico approaches. The structure of σETF was first built via three different computational methods. A cognate DNA sequence was then docked to the predicted σETF DNA-binding motifs. The binding free energy calculated using molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) for triplicate 50 ns simulation of σETF-DNA complex revealed favourable binding energy of DNA to σETF (average ∆Gbind = -34.57 kcal/mol) mainly driven by non-polar interactions. This study revealed that σETF LYS131, ARG133, PHE138, TRP146, ARG222, LYS225 and ARG226 are most likely the key residues upon the binding and recognition of DNA prior to transcription actives. Since determination of genome-regulating protein which recognises specific DNA sequence is important to discriminate between the proteins preferences for different genes, this study might provide some understanding on the possible σETF-DNA recognition prior to transcription initiated for the δ-endotoxins production.
Aqueous two-phase system (ATPS) extractive bioconversion provides a technique which integrates bioconversion and purification into a single step process. Extractive bioconversion of gamma-cyclodextrin (γ-CD) from soluble starch with cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) enzyme derived from Bacillus cereus was evaluated using polyethylene glycol (PEG)/potassium phosphate based on ATPS. The optimum condition was attained in the ATPS constituted of 30.0% (w/w) PEG 3000 g/mol and 7.0% (w/w) potassium phosphate. A γ-CD concentration of 1.60 mg/mL with a 19% concentration ratio was recovered after 1 h bioconversion process. The γ-CD was mainly partitioned to the top phase (YT=81.88%), with CGTase partitioning in the salt-rich bottom phase (KCGTase=0.51). Repetitive batch processes of extractive bioconversion were successfully recycled three times, indicating that this is an environmental friendly and a cost saving technique for γ-CD production and purification.