Single-channel properties of a stretch-sensitive chloride channel in the human mast cell line HMC-1

A stretch-activated (SA) Cl⁻ channel in the plasma membrane of the human mast cell line HMC-1 was identified in outside-out patch-clamp experiments. SA currents, induced by pressure applied to the pipette, exhibited voltage dependence with strong outward rectification (55.1 pS at +100 mV and an about tenfold lower conductance at −100 mV). The probability of the SA channel being open (P _o) also showed steep outward rectification and pressure dependence. The open-time distribution was fitted with three components with time constants of τ_1o = 755.1 ms, τ_2o = 166.4 ms, and τ_3o = 16.5 ms at +60 mV. The closed-time distribution also required three components with time constants of τ_1c = 661.6 ms, τ_2c = 253.2 ms, and τ_3c = 5.6 ms at +60 mV. Lowering extracellular Cl⁻ concentration reduced the conductance, shifted the reversal potential toward chloride reversal potential, and decreased the P _o at positive potentials. The SA Cl⁻ currents were reversibly blocked by the chloride channel blocker 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) but not by (Z)-1-(p-dimethylaminoethoxyphenyl)-1,2-diphenyl-1-butene (tamoxifen). Furthermore, in HMC-1 cells swelling due to osmotic stress, DIDS could inhibit the increase in intracellular [Ca²⁺] and degranulation. We conclude that in the HMC-1 cell line, the SA outward currents are mediated by Cl⁻ influx. The SA Cl⁻ channel might contribute to mast cell degranulation caused by mechanical stimuli or accelerate membrane fusion during the degranulation process.     

Antimicrobial activity of spherical silver nanoparticles prepared using a biocompatible macromolecular capping agent: evidence for induction of a greatly prolonged bacterial lag phase

Background  

We have evaluated the antimicrobial properties of Ag-based nanoparticles (Nps) using two solid phase bioassays and found that 10-20 μL of 0.3-3 μM keratin-stabilized Nps (depending on the starting bacterial concentration = C _I) completely inhibited the growth of an equivalent volume of ca. 10³ to 10⁴ colony forming units per mL (CFU mL^-1) Staphylococcus aureus, Salmonella Typhimurium, or Escherichia coli O157:H7 on solid surfaces. Even after one week at 37°C on solid media, no growth was observed. At lower Np concentrations (= [Np]s), visible colonies were observed but they eventually ceased growing.     

Effects of Artemisinin Derivative on the Growth Metabolism of <Emphasis Type="Italic">Tetrahymena thermophila</Emphasis> BF5 Based on Expression of Thermokinetics

The toxic effects of artesunate and dihydroartemisinin on the growth metabolism of Tetrahymena thermophila BF5 were studied by microcalorimetry. The results showed that: (1) low concentrations of artesunate (≤1 mg L⁻¹) and dihydroartemisinin (≤ 2 mg L⁻¹) promoted the growth metabolism of T. thermophila BF5, whereas high concentrations of artesunate (1–60 mg L⁻¹) and dihydroartemisinin (2–60 mg L⁻¹) inhibited its growth; (2) the half inhibition concentrations IC₅₀ of artesunate and dihydroartemisinin were 17.5817 and 9.5089 mg L⁻¹, respectively. It was concluded that the inhibition of dihydroartemisinin was stronger than that of artesunate.     

Effect of fungal infection on reproductive potential and survival time of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Tetranychidae)

The effect of fungal infection on the reproductive potential of two-spotted spider mite, Tetranychus urticae, was evaluated as part of the full biocontrol potential of three entomopathogenic fungi by modeling of fecundity probability. Female mites (≤2-day-old) on leaves were exposed to the sprays of Beauveria bassiana, Paecilomyces fumosoroseus and Metarhizium anisopliae at the concentrations of 1.13 × 10³, 1.55 × 10³ and 0.95 × 10³ deposited conidia mm⁻² and then individually reared at 25°C and 12:12 L:D for oviposition. Mite mortalities 10 days after spraying were 73.1, 75.4 and 67.9% in the fungal treatments versus 15.5% in control. On average, females infected by the three fungal species survived 5.8, 6.2 and 6.3 days, and laid 3.1, 4.0 and 4.0 eggs per capita, respectively. These were 3–4 fold lower than the control fecundity at 12.3. The cumulative probabilities [P(m ≤ N)] for the counts of infected and non-infected (control) females laying m eggs per capita (m ≤ N) during 10 days fit very well the equation P(m ≤ N) = 1/[1 + exp(a + bm)] (r ² ≥ 0.98), yielding a solution to the probability for the female mites to achieve a specific fecundity {P(m ≤ N)−P[m ≤ (N − 1)]}. Consequently, the infected mites had 71–78% chance to lay ≤5 eggs per capita but only 5–8% to deposit >10 eggs despite some variation among the tested fungi. In contrast, the chances for the non-infected mites to achieve the low and high fecundities were 23 and 55%. The fitted probabilities provide a full coverage of the fecundity potential of infected versus non-infected mites and are more informative than the mean fecundities.     

Development of a real-time TaqMan assay to detect <Emphasis Type="Italic">mendocina</Emphasis> sublineage <Emphasis Type="Italic">Pseudomonas</Emphasis> species in contaminated metalworking fluids

A TaqMan quantitative real-time polymerase chain reaction (qPCR) assay was developed for the detection and enumeration of three Pseudomonas species belonging to the mendocina sublineage (P. oleovorans, P. pseudoalcaligenes, and P. oleovorans subsp. lubricantis) found in contaminated metalworking fluids (MWFs). These microbes are the primary colonizers and serve as indicator organisms of biodegradation of used MWFs. Molecular techniques such as qPCR are preferred for the detection of these microbes since they grow poorly on typical growth media such as R2A agar and Pseudomonas isolation agar (PIA). Traditional culturing techniques not only underestimate the actual distribution of these bacteria but are also time-consuming. The primer–probe pair developed from gyrase B (gyrB) sequences of the targeted bacteria was highly sensitive and specific for the three species. qPCR was performed with both whole cell and genomic DNA to confirm the specificity and sensitivity of the assay. The sensitivity of the assay was 10¹ colony forming units (CFU)/ml for whole cell and 13.7 fg with genomic DNA. The primer–probe pair was successful in determining concentrations from used MWF samples, indicating levels between 2.9 × 10³ and 3.9 × 10⁶ CFU/ml. In contrast, the total count of Pseudomonas sp. recovered on PIA was in the range of <1.0 × 10¹ to 1.4 × 10⁵ CFU/ml for the same samples. Based on these results from the qPCR assay, the designed TaqMan primer–probe pair can be efficiently used for rapid (within 2 h) determination of the distribution of these species of Pseudomonas in contaminated MWFs.     

Aerobic biodegradation of nitrobenzene by a defined microbial consortium immobilized in polyurethane foam

An aerobic microbial consortium constructed by the combination of Rhodotorula mucilaginosa Z1, Streptomyces albidoflavus Z2 and Micrococcus luteus Z3 was immobilized in polyurethane foam and its ability to degrade nitrobenzene was investigated. Batch experimental results showed that polyurethane-foam-immobilized cells (PFIC) more efficiently degrade 200–400 mg l⁻¹ nitrobenzene than freely suspended cells (FSC). Kinetics of nitrobenzene degradation by PFIC was well described by the Andrews equation. Compared with FSC, PFIC exhibited better reusability (over 100 times) and tolerated higher shock-loadings of nitrobenzene (1,000 mg l⁻¹). Moreover, In the presence of salinity (≤5% NaCl, w/v), phenol (≤150 mg l⁻¹) and aniline (≤50 mg l⁻¹), respectively, degradation efficiency of nitrobenzene by PFIC reached over 95%. Even in the presence of both 100 mg l⁻¹ phenol and 50 mg l⁻¹ aniline, over 75% nitrobenzene was removed by PFIC in 36 h. Therefore, the immobilization of the defined consortium in polyurethane foam has application potential for removing nitrobenzene in industrial wastewater treatment system.     

Characterization and validation of a chemiluminescent assay based on 1,2-dioxetanes for rapid detection of viable Escherichia coli

[(4-methoxy-4(3-β-d-galactose-4-chlorophenyl)]spiro[1,2-dioxetane-3-1,3-tricyclo[7.3.1.0^2,7]tridec-2,7-ene] (“sβ-Gal 102”) and sodium [4-methoxy-4(3-β-d-glucuronic acid-4-chlorophenyl)]spiro[1,2-dioxetane-3-1,3-tricyclo[7.3.1.0^2,7]tridec-2,7-ene] (“sβ-Glucor 102”) are carbohydrate-containing 1,2-dioxetane compounds that produce chemiluminescence upon enzymatic hydrolysis by β-d-galactosidase, and β-d-glucuronidase, respectively. In this study, we have characterized and validated a sensitive detection principle for viable Escherichia coli based on enzymatic cleavage of sβ-Gal 102 and sβ-Glucor 102 (“ColiLight II”). The proposed chemiluminescent assay was optimized with respect to analytical requirements including incubation time, temperature, pH, enzyme induction, and cell permeabilization. The sensitivity and specificity rates of the assay were tested on ten different bacterial genera. The assay was found to be representative based on low coefficients of variations for both accuracy and precision. The analysis time was less than 1 h and the analytical detection limit was 10² to 10³ E. coli cells. In combination with membrane filtration and a brief resuscitation step of 4 h, the proposed assay was capable of detecting low concentrations of stressed E. coli in potable water (<30 CFU 100 ml⁻¹). The proposed chemiluminescent enzyme assay may be used for assessing the metabolic activity of E. coli in oligotrophic environments and for early warning detection of low concentrations of E. coli in water for human consumption.     

A process for the production of ectoine and poly(3-hydroxybutyrate) by <Emphasis Type="Italic">Halomonas boliviensis</Emphasis>

The paper reports a study involving the use of Halomonas boliviensis, a moderate halophile, for co-production of compatible solute ectoine and biopolyester poly(3-hydroxybutyrate) (PHB) in a process comprising two fed-batch cultures. Initial investigations on the growth of the organism in a medium with varying NaCl concentrations showed the highest level of intracellular accumulation of ectoine (0.74 g L⁻¹) at 10–15% (w/v) NaCl, while at 15% (w/v) NaCl, the presence of hydroxyectoine (50 mg L⁻¹) was also noted. On the other hand, the maximum cell dry weight and PHB concentration of 10 and 5.8 g L⁻¹, respectively, were obtained at 5–7.5% (w/v) NaCl. A process comprising two fed-batch cultivations was developed—the first culture aimed at obtaining high cell mass and the second for achieving high yields of ectoine and PHB. In the first fed-batch culture, H. boliviensis was grown in a medium with 4.5% (w/v) NaCl and sufficient levels of monosodium glutamate, NH₄⁺, and PO₄³⁻. In the second fed-batch culture, the NaCl concentration was increased to 7.5% (w/v) to trigger ectoine synthesis, while nitrogen and phosphorus sources were fed only during the first 3 h and then stopped to favor PHB accumulation. The process resulted in PHB yield of 68.5 wt.% of cell dry weight and volumetric productivity of about 1 g L⁻¹ h⁻¹ and ectoine concentration, content, and volumetric productivity of 4.3 g L⁻¹, 7.2 wt.%, and 2.8 g L⁻¹ day⁻¹, respectively. At salt concentration of 12.5% (w/v) during the second cultivation, the ectoine content was increased to 17 wt.% and productivity to 3.4 g L⁻¹ day⁻¹.     

Enhanced fructooligosaccharides and inulinase production by a <Emphasis Type="Italic">Xanthomonas campestris</Emphasis> pv. <Emphasis Type="Italic">phaseoli</Emphasis> KM 24 mutant

Xanthomonas campestris pv phaseoli produced an extracellular endoinulinase (9.24 ± 0.03 U mL⁻¹) in an optimized medium comprising of 3% sucrose and 2.5% tryptone. X. campestris pv. phaseoli was further subjected to ethylmethanesulfonate mutagenesis and the resulting mutant, X. campestris pv. phaseoli KM 24 demonstrated inulinase production of 22.09 ± 0.03 U mL⁻¹ after 18 h, which was 2.4-fold higher than that of the wild type. Inulinase production by this mutant was scaled up using sucrose as a carbon source in a 5-L fermenter yielding maximum volumetric (21,865 U L⁻¹ h⁻¹) and specific (119,025 U g⁻¹ h⁻¹) productivities of inulinase after 18 h with an inulinase/invertase ratio of 2.6. A maximum FOS production of 11.9 g L⁻¹ h⁻¹ and specific productivity of 72 g g⁻¹ h⁻¹ FOS from inulin were observed in a fermenter, when the mutant was grown on medium containing 3% inulin and 2.5% tryptone. The detection of mono- and oligosaccharides in inulin hydrolysates by TLC analysis indicated the presence of an endoinulinase. This mutant has potential for large-scale production of inulinase and fructooligosaccharides.     

Fed-batch production of a bioflocculant from <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis>

The constant-rate fed-batch production of the polygalacturonic acid bioflocculant REA-11 was studied. A controlled sucrose-feeding strategy resulted in a slight improvement in biomass and a 7% reduction in flocculating activity compared with the batch process. When fed with a 3 g l⁻¹ urea solution, the flocculating activity was enhanced to 720 U ml⁻¹ in 36 h. High cell density (2.12 g l⁻¹) and flocculating activity (820 U ml⁻¹) were obtained in a 10-l fermentor by feeding with a sucrose-urea solution, with values of nearly two times and 50% higher than those of the batch process, respectively. Moreover, the residual sucrose declined to 2.4 g l⁻¹, and residual urea decreased to 0.03 g l⁻¹. Even higher flocculating activity of 920 U ml⁻¹ and biomass of 3.26 g l⁻¹ were obtained by feeding with a sucrose-urea solution in a pilot scale fermentation process, indicating the potential industrial utility of this constant-rate feeding strategy in bioflocculant production by Corynebacterium glutamicum.     

Molecular cloning,genomic characterization and over-expression of a novel gene, <Emphasis Type="Italic">XRRA1</Emphasis>, identified from human colorectal cancer cell HCT116<Superscript>Clone2_XRR</Superscript> and macaque testis

Background  

As part of our investigation into the genetic basis of tumor cell radioresponse, we have isolated several clones with a wide range of responses to X-radiation (XR) from an unirradiated human colorectal tumor cell line, HCT116. Using human cDNA microarrays, we recently identified a novel gene that was down-regulated by two-fold in an XR-resistant cell clone, HCT116^Clone2_XRR. We have named this gene as X-ray radiation resistance associated 1 (XRRA1) (GenBank BK000541). Here, we present the first report on the molecular cloning, genomic characterization and over-expression of the XRRA1 gene.     

Comparative Tolerances of Various <Emphasis Type="Italic">Beauveria bassiana</Emphasis> Isolates to UV-B Irradiation with a Description of a Modeling Method to Assess Lethal Dose

The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1–1.6 J cm⁻² (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0–2.61 mW cm⁻². Irradiated conidia were then incubated for 24 h at 25°C under saturated humidity. The ratio of germination at each dose over that in the blank control was defined as survival index (I _s). For all isolates, the I _s − D observations fit well with the survival model I _s = 1/[1 + exp(a + bD)] (0.94 ≤ r ² ≤ 0.99) generated widely spanned lethal doses of 0.154–0.928, 0.240–1.139, and 0.383–1.493 J cm⁻² for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm⁻² measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses.     

Elicitation of guggulsterone production in cell cultures of <Emphasis Type="Italic">Commiphora wightii</Emphasis> by plant gums

Plant gum as an elicitor for guggulsterone production in cell cultures of Commiphora wightii is reported for the first time. Guggulsterone production increased 2.4 fold in the cell cultures by gum Arabic (100 mg l⁻¹), while mesquite gum elicited 2 fold. The cells treated with gum Arabic at 7th and 9th day accumulated enhanced guggulsterones within 24 h, which increased further up to 48 h and then declined. The cells treated at 9th day accumulated higher amount (218 μg l⁻¹) of guggulsterones after 48 h of elicitation as compared to cells treated at 7th day (164 μg l⁻¹). The optimized elicitation conditions were used in vessels of varying capacity where maximum yield of 285 μg l⁻¹ of guggulsterones was recorded in 3 l shake flasks. These experiments enabled highest guggulsterones yield in a short duration of 11 days in cell cultures of C. wightii.     

Effects of extracellular DNA and DNA‐binding protein on the development of a Streptococcus intermedius biofilm

Aims

The aim of this study was to clarify the effects of homologous and heterologous extracellular DNAs (eDNAs) and histone‐like DNA‐binding protein (HLP) on Streptococcus intermedius biofilm development and rigidity.

Methods and Results

Formed biofilm mass was measured with 0·1% crystal violet staining method and observed with a scanning electron microscope. The localizations of eDNA and extracellular HLP (eHLP) in formed biofilm were detected by staining with 7‐hydoxyl‐9H‐(1,3‐dichloro‐9,9‐dimethylacridin‐2‐one) and anti‐HLP antibody without fixation, respectively. DNase I treatment (200 U ml^?1) markedly decreased biofilm formation and cell density in biofilms. Colocalization of eHLP and eDNA in biofilm was confirmed. The addition of eDNA (up to 1 μg ml^?1) purified from Strep. intermedius, other Gram‐positive bacteria, Gram‐negative bacteria, or human KB cells into the Strep. intermedius culture increased the biofilm mass of all tested strains of Strep. intermedius, wild‐type, HLP‐downregulated strain and control strains. In contrast, the addition of eDNA (>1 μg ml^?1) decreased the biofilm mass of all Strep. intermedius strains.

Conclusions

These findings demonstrated that eDNA and eHLP play crucial roles in biofilm development and its rigidity.

Significance and Impact of the Study

eDNA‐ and HLP‐targeting strategies may be applicable to novel treatments for bacterial biofilm‐related infectious diseases.     

Comparative Permeabilities of the Paracellular and Transcellular Pathways of Corneal Endothelial Layers

Layers of rabbit corneal endothelial cells were cultured on permeable inserts. We characterized the diffusional permeability of the cell layer to nonelectrolyte and charged molecules and compared the diffusional and filtration permeabilities of the paracellular and transcellular pathways. We determined the rates of diffusion of ³H- and ¹⁴C-labeled nonelectrolyte test molecules and estimated the equivalent pore radius of the tight junction. Negatively charged molecules permeate slower than neutral molecules, while positively charged molecules permeate faster. Palmitoyl-dl-carnitine, which opens tight junctions, caused an increase of permeability and equivalent pore radius. Diffusional water permeability was determined with ³H-labeled water; the permeabilities of the tight junction and lateral intercellular space were calculated using tissue geometry and the Renkin equation. The diffusional permeability (P _d ) of the paracellular pathway to water is 0.57 μm s⁻¹ and that of the transcellular path is 2.52 μm s⁻¹. From the P _d data we calculated the filtration permeabilities (P _f ) for the paracellular and transcellular pathways as 41.3 and 30.2 μm s⁻¹, respectively. In conclusion, the movement of hydrophilic molecules through tight junctions corresponds to diffusion through negatively charged pores (r = 2.1 ± 0.35 nm). The paracellular water permeability represents 58% of the filtration permeability of the layer, which points to that route as the site of sizable water transport. In addition, we calculated for NaCl a reflection coefficient of 0.16 ≤ σ_NaCl ≤ 0.33, which militates against osmosis through the junctions and, hence, indirectly supports the electro-osmosis hypothesis.     

Associations between common variants in <Emphasis Type="Italic">GC</Emphasis> and <Emphasis Type="Italic">DHCR7</Emphasis>/<Emphasis Type="Italic">NADSYN1</Emphasis> and vitamin D concentration in Chinese Hans

Recent studies have identified common variants in or near GC, CYP2R1 and NADSYN1/DHCR7 to be associated with 25-hydroxyvitamin D [25(OH)D] levels in European populations. We aimed to examine whether these variants also influence 25(OH)D levels in Chinese. Seven common variants were successfully genotyped and tested for associations with plasma 25(OH)D levels in a population-based cohort of 3,210 Chinese Hans from Beijing and Shanghai. Six common variants at GC (rs4588, rs7041, rs2282679 and rs1155563) and NADSYN1/DHCR7 (rs3829251 and rs1790349) loci were all significantly associated with lower plasma 25(OH)D levels (−0.036 ≤ β ≤ −0.076 per risk-allele, P ≤ 5.7 × 10⁻⁵), while CYP2R1-rs2060793 showed a trend toward association with 25(OH)D levels in the Shanghai subpopulation (P = 0.08), but not in the Beijing subpopulation (P = 0.82). Haplotype-based association analyses of the four GC variants showed that only the haplotype that contained all risk-alleles (TACC) was significantly associated with lower plasma 25(OH)D levels (β = −0.085, P = 2.3 × 10⁻⁹), while the haplotype containing the risk-alleles of rs4588 and rs2282679 (TATC) was marginally associated with lower 25(OH)D levels (β = −0.054, P = 0.0562) when compared with GCTA haplotype carrying the four protective alleles. Most notably, conditional analyses showed that only GC-rs4588 and GC-rs2282679 (r ² = 0.97) remained significantly associated with 25(OH)D concentrations (P ≤ 1.9 × 10⁻⁵) after adjusting for the other two SNPs in GC. In conclusion, GC and NADSYN1/DHCR7 loci individually and collectively contribute to variation in plasma vitamin D levels in Chinese Hans.     

Production of tetramethylpyrazine by batch culture of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> with optimal pH control strategy

The effects of initial culture pH ranging from 5.0 to 7.5 on biomass content, precursor 3-hydroxy-2-butanone (HB) accumulation, and 2,3,5,6-tetramethylpyrazine (TTMP) formation by Bacillus subtilis CCTCC M 208157 were investigated in shake flask fermentation. Weak acidic conditions were found to favor cell growth and precursor HB accumulation, while TTMP could be synthesized more efficiently in conditions with initial pH towards neutrality. Batch bioprocess of TTMP fermentation by Bacillus subtilis CCTCC M 208157 at various controlled pH values ranging from 5.5 to 7.0 was then examined in 7.5-l fermentor. The results suggested that optimum pH for cell growth and precursor HB accumulation was 5.5 with maximum cell growth rate (Q _x) and precursor HB accumulation rate (Q _HB) of 0.833 g l⁻¹ h⁻¹ and 1.118 g l⁻¹ h⁻¹, respectively, while optimum pH for TTMP formation was 7.0 with maximum TTMP formation rate (Q _TTMP) of 0.095 g l⁻¹ h⁻¹. A pH-shifted strategy was accordingly developed to improve TTMP production in bioreactor fermentation by shifting the culture pH from 5.5 to 7.0 after 48 h of cultivation. By applying the strategy, final TTMP concentration of 7.43 g l⁻¹ was obtained, being 22.2% greater than that of constant-pH fermentation.     

Air biocontamination in a variety of agricultural industry environments in Egypt: a pilot study

Inhalation of airborne microorganisms and organic dust is an occupational concern among workers in agricultural industries. Airborne microorganisms and particulate matter samples were collected from poultry house, flourmill, textile, and food industry sites by use of liquid impinger and gravimetric samplers. Particulate matter concentrations were recorded at median concentrations of 1.56, 1.92, 4.39, and 0.7 mg/m³ in the occupied poultry house, textile, flourmill, and food indoor working environments, respectively. The highest median particulate matter concentration (27.9 mg/m³) was detected at the flourmill’s stack site. The highest median indoor concentration of culturable airborne bacteria (6.23 × 10⁵ CFU/m³) was found at the occupied poultry-house site and the lowest concentration (4.6 × 10³ CFU/m³) was found at the food industry site. The highest median indoor concentration of culturable airborne fungi (3.15 × 10⁴ CFU/m³) was found at the flourmill site whereas the lowest (1.24 × 10³ CFU/m³) was found at the textile industry site. Bacillus and Staphylococcus were the predominant Gram-positive bacteria whereas Acinetobacter and Klebsiella were the predominant Gram-negative bacteria. Escherichia coli and Salmonella were only detected in the indoor air at the poultry house site. Aspergillus flavus, Aspergillus niger, Penicillium, and yeast were the predominant fungal types at flourmill, textile, food industry, and poultry house, respectively. Workers were continuously exposed to airborne microorganisms at a median value of 10⁴ CFU/m³ in all the industries studied.