Development of a Low Cost Bioprocess for Endotoxin Production by Bacillus thuringiensis var israelensis Intended for Biological Control of Aedes aegypti

Aedes aegypti is the vector of Dengue disease, responsible for 20,000 deaths/year worldwide. Bacillus thuringiensis var israelensis - Bti releases selective and effective toxins (crystal proteins) against A. aegypti larvae. We present a low cost bioprocess for toxin production, accomplished by a selected Brazilian strain Bti (BR-LPB01) and employment of low cost substrates. Soybean meal and sugarcane molasses lead to high toxic effectiveness after 2L bioreactor fermentation (LD50=26ng/mL), near to the reference strain IPS82 (LD50=17.3 ng/mL). The pH ranged between 5.8 and 7.0 during the exponential growth period and between 7.0 and 8.4 during the stationary phase, with low activity. Thus, control of foam and pH 7.0 were started and proved to be crucial for high activity. It was verified that the fermentation could be discontinued after 20 hours, when the highest activity was present.

Download Full-text

Isolation of Bacillus thuringiensis strains that contain Dipteran-specific cry genes from Ilha Bela (São Paulo, Brazil) soil samples

Brazilian Journal of Biology ◽

10.1590/s1519-69842012000200003 ◽

2012 ◽

Vol 72 (2) ◽

pp. 243-247 ◽

Cited By ~ 6

Author(s):

EB. Campanini ◽

CC. Davolos ◽

ECC. Alves ◽

MVF. Lemos

Keyword(s):

Biological Control ◽

Bacillus Thuringiensis ◽

Aedes Aegypti ◽

Ribosomal Subunit ◽

Soil Samples ◽

Bacterial Isolates ◽

Cry Genes ◽

Cry Proteins ◽

Crystal Proteins ◽

Bacterium Bacillus

The entomophatogenic bacterium Bacillus thuringiensis produces crystal proteins, named Cry proteins which are encoded by the cry genes. This bacterium is used on biological control of important economical pests, as well as in the control of disease´s vectors, such as Aedes aegypti, a mosquito that transmits the dengue viruses. Isolates of this bacterium can be characterized by the content of cry genes and this prediction helps target different insect orders. In this research, we isolated 76 colonies of B. thuringiensis from 30 soil samples that were taken from Ilha Bela (SP, Brazil), a place where simulids are already biologically controlled by B. thuringiensis, to find bacterial isolates that were capable of controlling A. aegypti. The 16S ribosomal subunit genes of the selected isolates were sequenced, and the isolates were molecularly characterized based on their Dipteran-specific cry gene contents. Eight of the 76 isolates (10.52%) contained the cry4Aa, cry4Ba or cry10Aa genes, these isolates were carried out against A. aegypti larvae on bioassay. The presence or absence of specific cry genes was associated with the observed average larval mortalities. From the 76 isolates, seven (9.2%) were potentially able to control A. aegypti larvae. Therefore these are promising isolates for the biological control of A. aegypti larvae.

Download Full-text

GAMBARAN INDEKS LARVA AEDES AEGYPTI DI BUFFER WILAYAH KERJA BANDARA SEPINGGAN BALIKPAPAN

Medical and Health Science Journal ◽

10.33086/mhsj.v3i1.808 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Abdurrakhman abdurrakhman Abdurrakhman

Keyword(s):

Aedes Aegypti ◽

Buffer Zone ◽

Chi Square ◽

Cross Sectional ◽

Breeding Sites ◽

Dengue Disease ◽

Vector Borne Diseases ◽

Transportation Equipment ◽

Chi Square Test ◽

Larvae Density

ABSTRACT : The House index and Container Index in the buffer area of the working area of Balikpapan Sepinggan Airport is still above 1%, so the potential for the spread of dengue disease. Mobilization of people, goods and transportation equipment will increasingly affect the transmission of disease in ports and airports, especially for vector-borne diseases. This study aims to analyze the risk factors associated with larvae density of Aedes aegypti and describe the larvae index in the buffer zone of the Sepinggan Balikpapan Airport This study was a descriptive study with a cross sectional design. The sample in this study was 121 houses with a proportionate stratified random sampling, the research location was in the buffer zone of Sepinggan Balikpapan Airport in November 2018. The variables studied were houses with positive larvae containers, breeding sites and PSN behavior and larvasidation. The data was analyzed using the chi square test. There was a relationship between houses with larvae positive Aedes aegypti, behavior of Mosquito Nest Eradication (PSN) and larvasidation with larvae density of Aedes aegypti but not for breeding sites (p = 0.00 and 95% CI = 0.64), and (p = 0.00 and 95% CI = 0.34). The description of several Aedes aegypti larvae index, namely House Index (HI) = 57.02%, Container Index (CI) = 24.36%, Bruteau Index (BI) = 148.76, and Flick Free Numbers (ABJ) = 42.98 %. Houses with larvae of Aedes aegypti larvae and PSN and larvasidation behavior were associated with larvae density of Aedes aegypti. The index of HI, CI and BI larvae is of high value so there is a risk of DBD transmission

Download Full-text

Preparation of Organic Crystal Seed and Its Application in Improving the Functional Period of Biodegradable Agricultural Film

Crystals ◽

10.3390/cryst11070826 ◽

2021 ◽

Vol 11 (7) ◽

pp. 826

Author(s):

Runmeng Qiao ◽

Xin Wang ◽

Guangjiong Qin ◽

Qi Liu ◽

Jialei Liu ◽

...

Keyword(s):

Degradation Rate ◽

Low Cost ◽

Water Vapor Permeability ◽

Growth Period ◽

Nucleating Agent ◽

Degree Of Crystallinity ◽

Vapor Permeability ◽

Agricultural Films ◽

Degradation Degree ◽

Water Holding

White pollution caused by agricultural films has recently attracted great attention. In some areas, the content of micro plastic in the soil has reached 30 kg/ha. The most effective way to solve this problem is to replace traditional polyethylene agricultural films with degradable agricultural films. The consistency between the degradation rate and the crop growth period has become the biggest obstacle for the wide application of such novel agricultural films. In this paper, crystallinity regulation is used to adjust the functional period of degradable agricultural films. In addition, an organic nucleating agent of polyethylenimine (PEI) is selected by doping it to poly(butylene adipate-co-terephthalate) (PBAT) polymers using a double-screw extruder. The PBAT doped with 1 wt% PEI films revealed a significant increase in mechanical properties, water holding capacity, and crystallinity compared with the pure PBAT film. There was a 31.9% increase in tensile strength, a 30.5% increase in elongation at break, a 29.6% increase in tear resistance, a 30.9% decrease in water vapor permeability, and a 3.1% increase in crystallinity. Furthermore, the induction period of PBAT doped with 1 wt% PEI under photoaging (without soil) was about 160 h longer than PBAT film, and the experienced biodegradation in soil (without light) was 1 week longer than PBAT film. Experimental results exhibited that the change of degradation degree was linearly proportional to the degree of crystallinity. This study proposes a convenient, low-cost, and effective method to adjust the crystallinity and change the degradation rate.

Download Full-text

Temporal Variations in Patterns of Clostridioides difficile Strain Diversity and Antibiotic Resistance in Thailand

Antibiotics ◽

10.3390/antibiotics10060714 ◽

2021 ◽

Vol 10 (6) ◽

pp. 714

Author(s):

Supapit Wongkuna ◽

Tavan Janvilisri ◽

Matthew Phanchana ◽

Phurt Harnvoravongchai ◽

Amornrat Aroonnual ◽

...

Keyword(s):

Antibiotic Resistance ◽

Antimicrobial Susceptibility ◽

Reference Strain ◽

Toxin Production ◽

Temporal Variations ◽

Toxin Gene ◽

Data Sets ◽

Clostridioides Difficile ◽

Life Threatening ◽

Susceptibility Profiles

Clostridioides difficile has been recognized as a life-threatening pathogen that causes enteric diseases, including antibiotic-associated diarrhea and pseudomembranous colitis. The severity of C. difficile infection (CDI) correlates with toxin production and antibiotic resistance of C. difficile. In Thailand, the data addressing ribotypes, toxigenic, and antimicrobial susceptibility profiles of this pathogen are scarce and some of these data sets are limited. In this study, two groups of C. difficile isolates in Thailand, including 50 isolates collected from 2006 to 2009 (THA group) and 26 isolates collected from 2010 to 2012 (THB group), were compared for toxin genes and ribotyping profiles. The production of toxins A and B were determined on the basis of toxin gene profiles. In addition, minimum inhibitory concentration of eight antibiotics were examined for all 76 C. difficile isolates. The isolates of the THA group were categorized into 27 A−B+CDT− (54%) and 23 A-B-CDT- (46%), while the THB isolates were classified into five toxigenic profiles, including six A+B+CDT+ (23%), two A+B+CDT− (8%), five A−B+CDT+ (19%), seven A−B+CDT− (27%), and six A−B−CDT− (23%). By visually comparing them to the references, only five ribotypes were identified among THA isolates, while 15 ribotypes were identified within THB isolates. Ribotype 017 was the most common in both groups. Interestingly, 18 unknown ribotyping patterns were identified. Among eight tcdA-positive isolates, three isolates showed significantly greater levels of toxin A than the reference strain. The levels of toxin B in 3 of 47 tcdB-positive isolates were significantly higher than that of the reference strain. Based on the antimicrobial susceptibility test, metronidazole showed potent efficiency against most isolates in both groups. However, high MIC values of cefoxitin (MICs 256 μg/mL) and chloramphenicol (MICs ≥ 64 μg/mL) were observed with most of the isolates. The other five antibiotics exhibited diverse MIC values among two groups of isolates. This work provides evidence of temporal changes in both C. difficile strains and patterns of antimicrobial resistance in Thailand.

Download Full-text