Microbiological evaluation of infant foods quality and molecular detection of Bacillus cereus toxins relating genes

The Utilisation of Mushroom Leftovers, Oats, and Lactose-Free Milk Powder for the Development of Geriatric Formulation

This study aims to focus on developing a food supplement for the geriatric population using disposal mushrooms, oats, and lactose-free milk powder. Lactose intolerance is most common in older adults, raising the demand for lactose-free foods. One of the major global challenges currently faced by humankind is food waste (FW). Most of the food that is produced for human consumption has not been utilized completely (1/3rd-1/2 unutilized), resulting in agricultural food waste. Mushrooms are highly valuable in terms of their nutritional value and medicinal properties; however, a significant percentage of mushroom leftovers are produced during mushroom production that do not meet retailers' standards (deformation of caps/stalks) and are left unattended. Oats are rich in dietary fibre beta-glucan (55% water soluble; 45% water insoluble). Lactose-free milk powder, oats, and dried mushroom leftover powder were blended in different ratios. It was observed that increasing the amount of mushroom leftover powder increases the protein content while diluting calories. The product with 15% mushroom powder and 30% oat powder showed the highest sensory scores and the lowest microbial count. The GCMS and FTIR analyses confirmed the presence of ergosterol and other functional groups. The results of the XRD analysis showed that the product with 15% mushroom powder and 30% oat powder had a less crystalline structure than the product with 5% mushroom powder and 40% oat powder and the product with 10% mushroom powder and 35% oat powder, resulting in more solubility. The ICP-OES analysis showed significant concentrations of calcium, potassium, magnesium, sodium, and zinc. The coliform count was nil for the products, and the bacterial count was below the limited range (3 × 102 cfu/g). The product with 15% mushroom powder and 30% oat powder showed the best results, so this developed product is recommended for older adults.

Microbiological evaluation of the indigenous fermented condiment okpeye available at various retail markets in the south-eastern region of Nigeria

In Africa, indigenous fermented condiments contribute to food security as a low-cost source of protein. Okpeye is an indigenous fermented condiment produced from Prosopis africana seeds. The reliance on spontaneous fermentation processes and unhygienic practices during production often results in the contamination of the final product with microbial hazards. A microbiological evaluation of 18 commercial samples of okpeye purchased from six markets in two cities in southeastern Nigeria was conducted. Fifty-nine (59) bacteria were isolated and identified at the species level by phenotyping and sequencing the 16S rRNA, gyrB and rpoB genes. Bacillus (47.4 %) and Staphylococcus (42.3 %) were the predominant bacterial genera in okpeye. Overall, B. amyloliquefaciens and S. simulans were the most frequently occurring bacteria and were present in all samples. In addition, B. cereus was isolated in samples obtained from all markets. Other bacterial species included B. velezensis, Oceanobacillus caeni, S. cohnii, Escherichia fergusonni and Vagacoccus lutrae. The B. cereus isolates (10) were screened for the presence of 8 enterotoxin genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK, entFM) and one emetic gene (cesB). The non-haemolytic enterotoxin (nheABC) and haemolytic enterotoxin (hblABD) complexes were present in 70 % and 50 % of B. cereus respectively. The positive rate of cytK and entFM genes was 70 %, while the cesB gene was 30 %. Antibiotic susceptibility assessment showed that most of the isolates were susceptible to gentamicin, tetracycline, streptomycin, and erythromycin but resistant to ciprofloxacin and vancomycin. These findings highlight the need for further controls to reduce contamination with potential pathogenic bacteria in indigenous fermented condiments such as okpeye. There is also a need to educate producers regarding hygienic practices to safeguard public health and food security.

Enterococcus contamination of infant foods and implications for exposure to foodborne pathogens in peri-urban neighbourhoods of Kisumu, Kenya

We collected infant food samples from 714 households in Kisumu, Kenya, and estimated the prevalence and concentration of Enterococcus, an indicator of food hygiene conditions. In a subset of 212 households, we quantified the change in concentration in stored food between a morning and afternoon feeding time. In addition, household socioeconomic characteristics and hygiene practices of the caregivers were documented. The prevalence of Enterococcus in infant foods was 50% (95% confidence interval: 46.1 - 53.4), and the mean log10 colony-forming units (CFUs) was 1.1 (SD + 1.4). No risk factors were significantly associated with the prevalence and concentration of Enterococcus in infant foods. The mean log10 CFU of Enterococcus concentration was 0.47 in the morning and 0.73 in the afternoon foods with a 0.64 log10 mean increase in matched samples during storage. Although no factors were statistically associated with the prevalence and the concentration of Enterococcus in infant foods, household flooring type was significantly associated with an increase in concentration during storage, with finished floors leading to 1.5 times higher odds of concentration increase compared to unfinished floors. Our study revealed high prevalence but low concentration of Enterococcus in infant food in low-income Kisumu households, although concentrations increased during storage implying potential increases in risk of exposure to foodborne pathogens over a day. Further studies aiming at investigating contamination of infant foods with pathogenic organisms and identifying effective mitigation measures are required to ensure infant food safety.

Enterotoxigenic profiles and submerged and interface biofilms in Bacillus cereus group isolates from foods

Biofilm formation by Bacillus cereus strains is now recognized as a systematic contamination mechanism in foods; the aim of this study was to evaluate the production of submerged and interface biofilms in strains of B. cereus group in different materials, the effect of dextrose, motility, the presence of genes related to biofilms and the enterotoxigenic profile of the strains. We determine biofilm production by safranin assay, motility on semi-solid medium, toxin gene profiling and genes related to biofilm production by PCR in B. cereus group isolated from food. In this study, we observe strains used a higher production of biofilms in PVC; in the BHI broth, no submerged biofilms were found compared to phenol red broth and phenol red broth supplemented with dextrose; no strains with the ces gene were found, the enterotoxin profile was the most common the profile that includes genes for the three enterotoxins. We observed a different distribution of tasA and sipW with the origin of isolation of the strain, being more frequent in the strains isolated from eggshell. The production and type of biofilms are differential according to the type of material and culture medium used.

Bacteriological quality and safety of bottle food and associated factors among bottle-fed babies attending pediatric outpatient clinics of Government Health Institutions in Arba Minch, southern Ethiopia

BACKGROUND

Microbial contamination of baby bottle food has been identified as a significant public health concern, especially in developing countries, but it remains overlooked. Therefore, this study aimed to determine microbiological hazards, compliance with hygiene practices, and critical control points of contamination in baby bottle food in Arba Minch, southern Ethiopia.

OBJECTIVE

To evaluate the bacteriological quality and prevalence of foodborne pathogens in baby bottle food and to identify associated factors among bottle-fed babies attending three government health institutions in Arba Minch, southern Ethiopia.

METHODS

A cross-sectional study was conducted between February 24 and March 30, 2022. A total of 220 food samples, comprising four types prepared with different sources of materials, were collected from systematically selected bottle-fed babies attending health facilities. The data on sociodemographic characteristics, food hygiene, and handling practices were solicited by face-to-face interview using a semi-structured questionnaire. Food samples (10 mL) were quantitatively analyzed for total viable counts (TVC) and total coliform count (TCC) and qualitatively for the presence of common foodborne bacterial pathogens. Data were analyzed using SPSS; ANOVA and multiple linear regression analyses were done to identify factors influencing microbial counts.

RESULTS

Results revealed that the means and standard deviations of TVC and TCC were 5.3 ± 2.3 log₁₀ colony forming units (CFU)/mL and 4.1 ± 2.6 log₁₀ CFU/mL, respectively. Of the various food samples analyzed, 57.3 and 60.5% had a TVC and TCC above the maximum acceptable limits, respectively. The result of the ANOVA showed that there was a significant difference in the mean score of TCV and TCC among the four types of food samples (p < 0.001). Enterobacteriaceae were found in the majority of positive food samples (79.13%), followed by Gram-positive cocci (20.8%). Salmonella spp., diarrheagenic Escherichia coli, and Staphylococcus aureus were the common foodborne pathogens detected in 8.6% of tested foods. The regression result revealed that the type of baby food, hand washing practices of mothers or caregivers, and sterilizing and disinfecting procedures of feeding bottles are independent determinants of bacterial contamination (p < 0.001).

CONCLUSION

The high microbial load and the presence of potential foodborne bacterial pathogens in the bottle food samples analyzed indicate unsanitary practices and the potential risk of exposure to foodborne pathogens in bottle-fed babies. Thus, interventions such as educating parents about proper hygiene practices, sterilizing feeding bottles and limiting bottle feeding practices are critical to reducing the risk of foodborne to bottle-fed infants.

Preventive and curative effect of difenoconazole + azoxytrobin and thiophanate-methyl against lucky bamboo anthracnose disease caused by Colletotrichum dracaenophilum

In Egypt, Dracaena sanderiana (lucky bamboo) is an ornamental plant imported from several countries. Two weeks after they arrived at the nurseries, anthracnose indications were detected on the shoots of imported D. sanderiana samples. Four Colletotrichum spp. isolates were obtained from the symptomatic lucky bamboo plants. The obtained isolates belonged to the species of C. gloeosporioides or C. dracaenophilum based on their morphological characteristics and molecular biology analyses. Pathogenicity tests reveal that C. dracaenophilum isolate 4 was found to be more pathogenic than the other isolates. The in vitro investigation was conducted with the objectives of evaluating six systemic fungicides for their inhibitory effect against C. dracaenophilum. Data reveal that, thiophanate-methyl and difenoconazole + azoxytrobin at ≥15 ppm completely inhibited the pathogen growth. Tebuconazole and flusllazole inhibited growth completely at ≥20 ppm, whereas iprodione and cyprodinil + fludioxonil had a lower effect (56.6 and 54.4% reduction, respectively) at this dose. The in vivo investigation was conducted with the objectives of evaluating the preventive and curative effects of the most effective fungicides against anthracnose disease. Lucky bamboo plants were treated with fungicide and either inoculated or not with C. dracaenophilum before being left for 25 or 60 days. On both insidiously infected and vaccinated lucky bamboo plants, the combination of difenoconazole, azoxytrobin, and thiophanate-methyl at 20 ppm greatly reduced the development of anthracnose. Tebuconazole and flusllazole were found to be phytotoxic.

Nano-bioremediation of textile industry wastewater using immobilized CuO-NPs myco-synthesized by a novel Cu-resistant Fusarium oxysporum OSF18

Currently, bionanotechnologies are attracting great interest due to their promising results and potential benefits on many aspects of life. In this study, the objectives was to biosynthesis CuO-NPs using cell-free extract(s) of copper-resistant fungi and use them in bioremediation of textile industry wastewater. Out of 18 copper-resistant fungal isolates, the novel fungus strain Fusarium oxysporum OSF18 was selected for this purpose. This strain showed a high efficiency in extracellular reducing copper ions to their nano-form. The myco-synthesized CuO-NPs were characterized using UV-Vis spectroscopy, HRTEM, FTIR, and XRD and were found to be spherical nanocrystals with the size range of 21-47 nm. The bio-synthesized CuO-NPs showed promising antimicrobial activity as well as high efficiency in removing heavy metals and textile dye from industrial wastewater. The myco-synthesized CuO-NPs immobilized in alginate beads exhibited superior microbial disinfection (99.995%), heavy metals removal (93, 55, and 30 % for Pb, Cr, and Ni, respectively), and dye decolorization (90%). Such results represent a promising step to produce an eco-friendly, cost-effective, and easy-to handle tool for the bioremediation of textile industry wastewater.

Isolation of Haematococcus lacustris as source of novel anti-multi-antibiotic resistant microbes agents; fractionation and identification of bioactive compounds

In this work, freshwater microalga, Haematococcus lacustris was isolated from the River Nile, identified and deposited in genebank under name of H. lacustris isolate REH10 with accession number OK336515. N-hexane extract was produced high inhibition effects against multi-antibiotic resistant pathogens. The n-Hexane extract was fractionated and 2 fractions (F3 & F4) exhibited high antibacterial activity (15 - 20 mm) compared with other fractions. Thus, they sub-fractionated and 2 sub-fractions produced from the F3 had high inhibition activity against all tested pathogens (18-20 mm). To identify the main compounds responsible for inhibition growth of multi-drug resistance bacteria, GC-MS chromatogram analyses was applied on the F3 and its sub-fractions 2 and 3. Five compounds detected in the 2 sub-fractions. Palmitic acid was identified as the first report antibacterial agent. The antioxidant activity of SF3-3 was reached to 86 and 80.5% for DPPH and ABTS.⁺ tests, respectively.

Prevalence of Bacillus cereus in dairy powders focusing on its toxigenic genes and antimicrobial resistance

Bacillus cereus is a common environmental foodborne microorganism that is mainly found to harbor toxigenic genes with multiple antibiotic resistances and is linked to threatening the safety of dried milk in concern to powdered infant milk formula. In the current investigation, the mean value of B. cereus in 140 samples of powdered milk was 0.57 × 10² ± 0.182 × 10², 0.15 × 10² ± 0.027 × 10², 0.21 × 10² ± 0.035 × 10², and 0.32 × 10² ± 0.072 × 10² CFU/g in a percentage of 64.0 samples of whole milk powder, 43.3 of skim milk powder, 26.7 of powdered infant milk formula and 36.7 milk–cereal-based infant formula, respectively. The results revealed that B. cereus isolates were found to harbor toxigenic genes in the following percentages: 77.8, 2.0, 72.7, 16.2, and 67.7 for nhe, hbl, cytK, ces, and bceT, respectively. Despite all evaluated B. cereus strains were originated from dairy powders, they showed a significant difference (P < 0.05) in their harbored toxigenic cytK gene between whole and skim milk powders with powdered infant formula and milk–cereal-based infant formula, as well as between powdered infant formula and milk–cereal-based infant formula. All isolated B. cereus strains were resistant to cefoxitin, colistin sulfate, neomycin, trimethoprim–sulfamethoxazole, oxacillin, and penicillin. Based on the antimicrobial resistance of B. cereus strains to cephalothin, chloramphenicol, nalidixic acid, and tetracycline, there was a significant difference (P < 0.05) between powdered infant milk formula and whole milk powder strains. This survey is one of few studies proceeded in Egypt to determine the prevalence of toxigenic B. cereus strains in milk–cereal-based infant formula and powdered infant formula as well as skim milk powder.

Effect of infant meal home preparation temperature on surviving of Bacillus cereus sensu lato: A case of Bechar city, Algeria

This work aimed to enumerate the Bacillus cereus sensu lato from infant’s flour sampled at Béchar city and evaluate its resistance to different heating conditions during meal preparation patterns at home. Our findings revealed a prevalence of 74% with 2.4 to 3.9 CFU/g in the analyzed samples. Regarding the heat resistance at 90 °C to 98 °C, our results showed heat resistance variability which depends on the isolate, for example, D90 °C and zT °C values varied from 3.24 to 5.52 min and 11.56 to 89.74 °C respectively. Then, the decimal reduction (n) was calculated at all preparation temperatures (50, 60, 70, 80, 90 and 100 °C). Low “n” was observed with the preparation at T≤50 °C as recommended by the fabricant. However, at the other temperatures, high “n” was observed at 100°C with median and 95th values of 2.22 and 12.36 respectively. Therefore, bacterial concentrations (99th) were estimated at 0.124 log CFU/g for 100 °C. These concentrations could be increased with bacterial growth during meal storage and then achieve critical concentrations. Thus, the results of this work highlight the interest to establish a risk assessment for babies and to improve the production, preparation, and storage conditions of the infant’s flour.

The Investigation of Mycotoxins and Enterobacteriaceae of Cereal-Based Baby Foods Marketed in Turkey

In this study, a total of 85 cereal-based baby foods with or without milk (four different brands; A, B, C, and D) collected from Ankara local markets, Turkey were analyzed for mycotoxins, total aerobic mesophilic bacteria (TAMB), and Enterobacteriaceae contamination. Baby foods were analyzed for 12 toxicological important mycotoxins such as aflatoxin B1, B2, G1, and G2; fumonisin B1 and B2; ochratoxin A; sterigmatocystin (STE); deoxynivalenol (DON); zearalenone (ZON); and T-2 toxin and HT-2 toxin by LC-MS/MS multi-mycotoxin method. In addition to these mycotoxins, the presence of aflatoxin M1 (AFM1) was investigated in baby foods containing milk. The classical culture method was used for microbiological analysis. Consequently, at least one mycotoxin was detected in 69.41% of the total samples. The most frequently detected mycotoxins were STE (34.12%) and HT-2 (34.12%). However, AFM1 was not detected in any of the baby foods containing milk. Also, TAMB and Enterobacteriaceae were isolated from 30.59% and 10.59% of samples, respectively. As a result, it was determined that the mycotoxin levels in the analyzed samples were in accordance with the mycotoxin levels specified in the Turkish Food Codex.

Paper-based sensor from pyrrolidinyl peptide nucleic acid for the efficient detection of Bacillus cereus

Bacillus cereus is one of the most common foodborne pathogens found in various kinds of staple foods such as rice and wheat. A rapid and accurate detection method for this pathogen is highly desirable for the sustainable production of relevant food products. While several classical and molecular-based detection methods are available for the identification of B. cereus, they suffered one or more limitations such as the requirement for a tedious and time-consuming process, less than ideal specificity, and the lack of portability. Herein, we developed the first paper-based sensing device that exhibits high species specificity with sufficiently low limit of detection for the visual detection of specific DNA sequences of B. cereus. The success is attributed to the strategic planning of fabrication in various dimensions including thorough bioinformatics search for highly specific genes, the use of the pyrrolidinyl peptide nucleic acid (PNA) probe whose selectivity advantage is well documented, and an effective PNA immobilization and DNA-binding visualization method with an internal cross-checking system for validating the results. Testing in rice matrices indicates that the sensor is capable of detecting and distinguishing B. cereus from other bacterial species. Hence, this paper-based sensor has potential to be adopted as a practical means to detect B. cereus in food industries.

Bacillus cereus food intoxication and toxicoinfection

Bacillus cereus is one of the leading etiological agents of toxin-induced foodborne diseases. Its omnipresence in different environments, spore formation, and its ability to adapt to varying conditions and produce harmful toxins make this pathogen a health hazard that should not be underestimated. Food poisoning by B. cereus can manifest itself as an emetic or diarrheal syndrome. The former is caused by the release of the potent peptide toxin cereulide, whereas the latter is the result of proteinaceous enterotoxins (e.g., hemolysin BL, nonhemolytic enterotoxin, and cytotoxin K). The final harmful effect is not only toxin and strain dependent, but is also affected by the stress responses, accessory virulence factors, and phenotypic properties under extrinsic, intrinsic, and explicit food conditions and host-related environment. Infamous portrait of B. cereus as a foodborne pathogen, as well as a causative agent of nongastrointestinal infections and even nosocomial complications, has inspired vast volumes of multidisciplinary research in food and clinical domains. As a result, extensive original data became available asking for a new, both broad and deep, multifaceted look into the current state-of-the art regarding the role of B. cereus in food safety. In this review, we first provide an overview of the latest knowledge on B. cereus toxins and accessory virulence factors. Second, we describe the novel taxonomy and some of the most pertinent phenotypic characteristics of B. cereus related to food safety. We link these aspects to toxin production, overall pathogenesis, and interactions with its human host. Then we reflect on the prevalence of different toxinotypes in foods opening the scene for epidemiological aspects of B. cereus foodborne diseases and methods available to prevent food poisoning including overview of the different available methods to detect B. cereus and its toxins.

High Risk of Potential Diarrheagenic Bacillus cereus in Diverse Food Products in Egypt

ABSTRACT

Bacillus cereus is one of the important foodborne pathogens that can be found in various foodstuffs, causes diarrheal and/or emetic syndromes, and can cause severe systemic diseases that may lead to death. This study was conducted to evaluate the prevalence, antimicrobial susceptibility profile, pathogenic potential, and genotypic diversity of B. cereus isolates recovered from diverse food products collected from markets in Cairo, Egypt. Of 165 food samples investigated in this study, 39 (24%) were positive for B. cereus, with contamination levels of 2 to 6 log CFU/g or mL and a higher prevalence of levels >3 log CFU. Antimicrobial susceptibility testing revealed that the B. cereus isolates were fully sensitive to all tested antimicrobial agents except β-lactams. The pathogenic potential of the 39 B. cereus isolates was assessed by detecting and profiling genes encoding virulence factors or toxins: the chromosomal genes hblA, bceT, plc, sph, nheA, entFM, and cytK associated with the diarrheal syndrome and the plasmid ces gene associated with the emetic syndrome. The most frequently detected genes were hblA, nheA, and entFM. All isolates harbored more than one of the diarrheal enterotoxin genes, and the genetic profile hblA-bceT-nheA-entFM-cytK-plc-sph was the most prevalent (20 of 39 isolates). The emetic toxin gene ces was not detected in any isolate. Enterobacterial repetitive intergenic consensus analysis of the 20 B. cereus isolates harboring the most prevalent genetic profile revealed that these isolates were genetically distinct, with a Simpson index of diversity value of 0.989. These findings provide useful information for public health management and serve as a warning of the potential risk of diarrheagenic B. cereus in diverse food products. Therefore, extensive study of the epidemiology of this food pathogen in Egypt is warranted. Strict procedures should be developed to monitor, protect, and safely handle food products, particularly ready-to-eat foodstuffs that are usually consumed without heat treatment.

HIGHLIGHTS

Isolation and Optimization of Monascus ruber OMNRC45 for Red Pigment Production and Evaluation of the Pigment as a Food Colorant

The color of food is a critical factor influencing its general acceptance. Owing to the effects of chemical colorants on health, current research is directly aimed at producing natural and healthy food colorants from microbial sources. A pigment-producing fungal isolate, obtained from soil samples and selected based on its rapidity and efficiency in producing red pigments, was identified as Monascus ruber OMNRC45. The culture conditions were optimized to enhance pigment production under submerged fermentation. The optimal temperature and pH for the highest red pigment yield were 30 °C and 6.5, respectively. The optimum carbon and nitrogen sources were rice and peptone, respectively. The usefulness of the pigment produced as a food colorant was evaluated by testing for contamination by the harmful mycotoxin citrinin and assessing its biosafety in mice. In addition, sensory evaluation tests were performed to evaluate the overall acceptance of the pigment as a food colorant. The results showed that M. ruber OMNRC45 was able to rapidly and effectively produce dense natural red pigment under the conditions of submerged fermentation without citrinin production. The findings of the sensory and biosafety assessments indicated the biosafety and applicability of the red Monascus pigment as a food colorant.

Frequency of hemolysin BL and non-hemolytic enterotoxin complex genes of Bacillus cereus in raw and cooked meat samples in Zanjan, Iran

Food safety has emerged as an important global issue with international trade and public health implications. Bacillus cereus is an important cause of food poisoning worldwide. A total of 200 individual meat samples were collected from meat retail outlets and restaurants and investigated the frequency of B. cereus and hemolysin BL (Hbl), non-hemolytic enterotoxin (Nhe) complex genes. The meat samples were immediately homogenized and cultured on Bacillus cereus selective agar and subjected for confirmatory biochemical tests and molecular detection of gyrB, hblA, hblC, hblD, nheA, nheB and nheC genes. A total of 29 (14.5 %) meat samples were positive for the presence of B. cereus. The frequency of B. cereus in raw meat (14.1 %) was similar to cooked beef samples (15 %) (P >  0.05). Twenty six (89.6 %) isolates carried at least one or more enterotoxin genes. We found nheA (58.6 %) and hblD (51.7 %) genes with higher frequency than others. Hemolysin BL complex genes were found in lower frequency than Nhe complex (P >  0.05). Detection of enterotoxigenic B. cereus in meat samples shows a probable risk for public health. Therefore, the reliable molecular methods for monitoring of potentially pathogenic B. cereus are strongly recommended for the routine food examination.

Evaluation of multidrug-resistant Bacillus strains causing public health risks in powdered infant milk formulas

BACKGROUND

Antibiotic-resistant bacteria are one of the major global health issues that can affect humans, animals, and the environment. Antibiotic-resistant bacteria have emerged as opportunistic pathogenic bacteria that are frequently isolated from both clinical patients and healthy individuals. The aim of this study was to characterize the antibiotic-resistant bacteria isolated from powdered infant formulas marketed in Riyadh, Saudi Arabia.

METHODS

Infant powdered milk formulas were purchased from different pharmacies located within Riyadh, and ten products of powdered milk formulas designed for children of various ages were then transferred to the laboratory in the Department of Botany and Microbiology at King Saud University, Riyadh. Isolation and purification of Bacillus species were both performed according to standard protocols. The identification test was performed using the automated Vitek 2 system (BioMerieux, France), and antibiotic sensitivity tests were performed using the disk-diffusion method incorporating standard antibiotic disks foramikacin (30μg/disk), gentamicin (10μg/disk), imipenem (10μg/disk), moxifloxacin (5μg/disk), cefoperazone (75μg/disk), cefpodoxime (10μg/disk), ceftazidime (30μg/disk), and cefepime (30μg/disk). Statistical analysis was performed using Ward's method to obtain antibiotic resistance of the isolates.

RESULTS

The results obtained from the milk samples indicated that all isolates were sensitive to amikacin, gentamicin, and moxifloxacin. A group of isolates obtained from milk was resistant to cefoperazone by 6.49%, cefpodoxime by 25.9%, ceftazidime by 14.28%, and cefepime by 19.48%.

CONCLUSIONS

Based on these findings, we concluded that the powdered infant formula marketed in Riyadh City may act as a source of bacterial isolates that are resistant to several standard antibiotics.

Metabolism and removal of anthracene and lead by a B. subtilis-produced biosurfactant

Most of effluents discharged to the environment contain toxic contaminants such as aromatic compounds and heavy metals which are considered hazardous to the nature and living organisms. In this study, Bacillus subtilis resistant to anthracene and lead was isolated from Persian Gulf sediments. Biosurfactant production was demonstrated using three methods, drop collapse, blood agar and oil spreading. Evaluation of optical density by spectrophotometer showed the bacterial growth in presence of 30 mg/l of anthracene and 50 mg/l of lead. Considerable proportion of anthracene (69.95%) was reduced after 120 h and the maximum percentage of lead absorption (82%) was observed after 150 min. The results indicated that the isolated bacterium was capable of removing anthracene and lead.