The efficacy of povidone-iodine,hydrogen peroxide and a chemical multipurpose contact lens care system against Pseudomonas aeruginosa on various lens case surfaces

PurposeTo determine the antimicrobial efficacy of a povidone-iodine system (PVP-I; cleadew, OPHTECS Corporation, Kobe, Japan), a peroxide system (AOSEPT Plus with HydraGlyde, Alcon, Fort Worth, TX), and a chemical multipurpose system (renu fresh, Bausch & Lomb, Rochester, NY) on contact lens case surfaces that are both in contact and not in contact with the solutions during lens disinfection.MethodsThe surfaces of the inner walls, underside of the lid, and lens holder (if applicable) of the cases were inoculated with P. aeruginosa ATCC 27853. The cases were disinfected with the solutions as per their manufacturer instructions. After disinfection, the inoculated surfaces were swabbed and the amount of surviving P. aeruginosa was determined. Following this experiment, separate cases were inoculated and disinfected as before. This time the cases were agitated after recommended disinfection time and the amount of P. aeruginosa in the disinfecting solution was quantified immediately, and again after resting for 7 days. Experiments were conducted in triplicate (n = 3).ResultsUnits are expressed in log CFU. All three solutions significantly reduced P. aeruginosa on direct-contact surfaces (all p < 0.039). On non-contact surfaces, the reduction of P. aeruginosa in the PVP-I system (pre-disinfection: 6.8 ± 0.5, post-disinfection: 1.0 ± 0.0; p < 0.001) was significant, but not for the hydrogen peroxide system (pre-disinfection: 6.3 ± 0.6, post: 5.5 ± 0.5; p = 0.194) and the chemical multipurpose system (pre-disinfection: 6.6 ± 0.1, post-disinfection: 5.6 ± 0.8; p = 0.336). After 7 days post-disinfection, no P. aeruginosa regrowth was observed in the PVP-I system (Day 1: 1.0 ± 0.0, Day 7: 1.0 ± 0.0; p = 1) and the chemical multipurpose system (Day 1: 4.2 ± 0.2, Day 7: 1.8 ± 0.9; p = 0.012), however regrowth was observed in the hydrogen peroxide system (Day 1: 3.4 ± 0.6, Day 7: 6.1 ± 0.4; p = 0.003).ConclusionThe PVP-I system was more effective against P. aeruginosa on non-contact surfaces than the hydrogen peroxide system or the chemical multipurpose system and is capable of inhibiting regrowth of P. aeruginosa for at least 7 days post-disinfection.     

Microbial adherence to cosmetic contact lenses

AimTo investigate whether cosmetic contact lenses (CCL) with surface pigments affect microbial adherence.MethodFifteen brands of CCL were purchased from optical, non-optical retail outlets, and via the Internet. A standardized rub-off test was performed on each CCL (five lenses per brand) to confirm the location of the pigments. The rub-off test comprised gentle rubbing on the surfaces of each CCL with wetted cotton buds for a maximum of 20 rubs per surface. A new set of CCL (five lenses per brand) were incubated in Pseudomonas aeruginosa overnight. Viable counts of adhered bacteria were determined by the number of colony-forming units (CFU) on agar media on each lens. The adherence of P. aeruginosa as well as Staphylococcus aureus and Serratia marcescens to three brands of CCL (A–C) (five lenses per brand) were also compared to their adherences on their clear counterparts.ResultsOnly two of the 15 brands of CCL tested (brands B and C) had pigments that did not detach with the rub-off test. The remaining 13 brands of CCL all failed the rub-off test and these lenses showed higher P. aeruginosa adherence (8.7 × 10⁵–1.9 × 10⁶ CFU/lens). Brands B and C lenses showed at least six times less bacterial adhesion than the other 13 brands. Compared to their clear counterparts, bacterial adherence to brands B and C lenses did not differ significantly, whereas brand A lenses showed significantly higher adherence.ConclusionSurface pigments on CCL resulted in significantly higher bacterial adherence.     

Control of Salmonella in food related environments by chemical disinfection

Salmonella may be transferred to food through cross-contamination during processing and preparation. To minimise the risk of cross-contamination, proper cleaning and disinfection is essential for the food industry. Recently, disinfection of areas for preparation and storage of food has also gained increased popularity in households. There is a range of disinfectants available with different properties and usage areas, and care must be taken to choose the proper disinfectant for the specific application.There are many methods for testing the antimicrobial effect of disinfectants. To evaluate whether a disinfectant will be effective in practical settings, the test method should model real-life situations. Most disinfectants are effective against Salmonella at recommended user concentration in suspension tests. However, a number of factors may reduce the biocidal effect of disinfectants under practical conditions. This include properties of the surface to be disinfected, presence of soiling on the surface, the physiological state of the bacteria exposed to disinfection, including bacteria embedded in biofilms, and the effects of other stresses (e.g. desiccation, starvation and temperature).Here we review the effects of disinfectants used in food related areas in industries and in households against Salmonella. A general overview is given for disinfectants in use and methods used to evaluate effects. Effects of disinfectants against Salmonella in suspension and on surfaces, including biofilms, are presented and compared. Novel control strategies such as use of electrolysed water, antimicrobial surfaces, and anti-biofilm compounds are also covered. Finally, we review the ability of Salmonella to gain reduced susceptibility to disinfectants through adaptation and other physiological responses like biofilm formation.     

Screening of antimicrobial activities of disinfectants and cleaning agents against foodborne spoilage microbes

 The antimicrobial activities of six disinfectants and cleaning agents against five food and brewery spoilage microbes were studied using the 5-5-5 suspension and a surface test simulating surface disinfection in actual use. The tests were carried out using the lowest recommended concentrations. The surface test was performed both with and without organic soil for various exposure times. In the suspension test, almost all the disinfectant and cleaning agents had adequate antimicrobial activity, except against Bacillus spores. The peroxide-based disinfectant and the isopropanol-based cleaning agent were both ineffective against Saccharomyces cerevisiae. In the surface test without soil the hypochlorite-based disinfectant was effective after an exposure of 10 min against all the microbes tested. The isopropanol-based cleaning agent was effective against all the vegetative cells tested. In the presence of soil, hypochlorite was effective against Listeria monocytogenes and Pseudomonas aeruginosa. In the test performed the lubricant which contained disinfectant had no antimicrobial activity against the surface-attached contaminants tested. P. aeruginosa was the most sensitive test organism and the Bacillus spores were the most resistant towards the agents tested. Received: 30 June 1998     

Comparison of growth and disinfectant resistance of Bacillus cereus isolated from fresh-cut produce and organic vegetables

Bacillus cereus strains were inoculated into tryptic soy broth (TSB) and incubated (7–35°C). Exponential and stationary phase cells were subjected to TSB plus sodium hypochlorite (0–3.6%), hydrogen peroxide (0–0.28%), and acetic acid (0–1.5%). Populations were counted on tryptic soy agar. Linear regression was fitted to survival data to calculate death rates. Cell counts decreased at 7°C. Differences in growth patterns were observed at 10°C and 15°C. Exponential and stationary phase cells showed significant (p<0.05) differences in disinfectant resistance. Strains treated with different disinfectants showed differences in growth and disinfectant resistance during different growth phases.     

3种常用消毒剂对沙门氏菌抑菌效果的研究

目的探讨3种常用消毒剂对沙门氏菌的抑菌效果,明确沙门氏菌对这3种消毒剂耐受效果,为消毒剂的科学使用提供参考。方法按照国家标准GB 4789.4-2010分离沙门氏菌和确定血清分型,用VITEK 2COMPACT鉴定菌株,选用抑菌环检测洗必泰、新洁尔灭、84消毒液3大类消毒剂对沙门氏菌的抑菌效果,确定最优消毒浓度。结果 10株沙门氏菌共获得3种血清型,其中肠炎沙门氏菌6株,鼠伤寒沙门氏菌3株,舒卜拉沙门氏菌1株;常规浓度的新洁尔灭对沙门氏菌具有完全的抑制作用,有效氯含量为0.4%的84消毒液对沙门氏菌具有完全抑制作用,而洗必泰需达0.4%浓度或以上才表现出对沙门氏菌完全抑制。结论不同的消毒场所应科学选择不同消毒剂浓度及消毒剂种类。     

The impact of a rub and rinse regimen on removal of human coronaviruses from contemporary contact lens materials

PurposeTo assess the influence of contemporary contact lens (CL) materials on human coronavirus attachment and the influence of a rub and rinse step to remove these viruses.MethodsThe binding rates of HCoV-229E and HCoV-OC43 to eight soft CL materials and four rigid gas permeable materials were analyzed. The impact of a rub and rinse step to remove these viruses from all materials was examined. The efficacy of Biotrue (Bausch & Lomb), OPTI-FREE Puremoist (Alcon), Clear Care (Alcon) and cleadew (Ophtecs) to remove virus contamination from two representative soft lens materials (etafilcon A and lotrafilcon B) was also determined.ResultsApproximately 10² to 10³ infectious viral particles were recovered from each CL material. Although some materials were more prone to coronavirus adhesion, contamination of both viral types was reduced to below the limit of quantification (LQ) from all materials using a simple saline rinse step. Exposure to Clear Care and cleadew reduced the number of infectious viral particles from both etafilcon A and lotrafilcon B to below the LQ, while for Biotrue and OPTI-FREE Puremoist, infectious viral particles were reduced to below the LQ only when additional rub and rinse steps were included.ConclusionHuman coronavirus contamination can be easily removed from CL surfaces. Although CL care products containing hydrogen peroxide and povidone-iodine efficiently removed virus contamination from CL surfaces without the need for a rub and rinse step, a full regimen including rub and rinse steps is crucial when using CL care products based on non-oxidative systems.     

The use of daily disposable lenses in problematic reusable contact lens wearers

PurposeReplacing soft contact lenses (CLs) on a daily basis brings a number of advantages, most notably, reduced exposure to deposits, disinfectants, allergens, and other contaminants. This retrospective study estimated the prevalence of problems in current wearers of reusable soft CLs and tested the effect of refitting “problem” patients with daily disposable (DD) hydrogel lenses.MethodsPrevalence was estimated from 398 current reusable CL wearers for: frequent/constant discomfort or dryness, ≥2 h of uncomfortable wear, ≥grade 2 conjunctival hyperaemia (0–4), or ≥grade 3 corneal staining (0–15). In the second part of the study, 217 reusable CL wearers classified as problem patients were randomly refitted with DD lenses manufactured from one of two materials: etafilcon A (n = 96) or nelfilcon A (n = 121) and reassessed 1 week later.ResultsThirty-nine percent (154/398) had some qualifying criterion: reduced comfortable wearing time (CWT), 20%; dryness, 20%; irritation, 5%; corneal staining, 8%; and hyperaemia, 7%. After refitting with DDs, the prevalence of reduced CWT was decreased from 65% to 51% (P = 0.0039), dryness from 60% to 41% (P < 0.0001) and corneal staining from 28% to 21% (P = 0.04). There was no significant change in the prevalence of irritation, or hyperaemia. Some differences were noted between the two lens materials.ConclusionsA high proportion of reusable soft lens wearers encounter clinically relevant signs or symptoms with their current CLs. This study provides evidence that refitting with DD lenses is a useful strategy for alleviating some of the common problems of CL wear.     

奶牛场采奶环节大肠埃希氏菌分离鉴定及对抗生素和消毒剂的抗性分析

为了解奶牛场采奶过程中大肠埃希氏菌污染状况、菌株所携带毒力基因及其对抗生素和消毒剂抗性。选择成都市某奶牛场随机采集655份样品,对致病性大肠埃希氏菌进行分离鉴定,并检测分离株携带的毒力基因、耐药基因以及抗消毒剂基因,筛选出毒力强菌株,分别检测菌株对抗生素和消毒剂的敏感性。结果表明,一共分离得到249株大肠埃希氏菌,鉴定致病性大肠埃希氏菌有123株,其中,肠道聚集性大肠埃希氏菌(EAEC)为该奶牛场主要致病性大肠埃希氏菌,占比77.23%;16株携带2~4种毒力基因不同来源菌株被挑选出来,检出了14种耐药基因和1种耐消毒剂基因。药敏试验中,耐药性最高为杆菌肽B(100.00%),依次是青霉素(93.75%)、利福平和万古霉素(87.50%),菌株呈现多重耐药现象(2~10耐);针对选取的8种常用消毒剂,发现3种对奶牛场中绝大多数大肠埃希氏菌有显著抑菌效果,可推荐使用。该奶牛场致病性大肠埃希氏菌以EAEC为主,菌株对抗生素和消毒剂有一定的抗性,应引起重视。     

Clinical performance of 'no rub' multi-purpose solutions.

This was a multi-site, 231-subject double-masked, bilateral crossover study to evaluate subjective comfort and satisfaction, corneal staining and lens deposits with two 'no rub' multi-purpose solutions (MPS) used with FDA Group II (alphafilcon A, SofLens 66, Bausch & Lomb) and Group IV (etafilcon A, SUREVUE, Johnson & Johnson Vision Care) soft contact lenses. Subjects used each of the two MPS, Regimen 1 (OPTI-FREE EXPRESS Multi-Purpose Disinfecting Solution No Rub Lasting Comfort Formula, Alcon Laboratories) and Regimen 2 (ReNu MultiPlus Multi-Purpose Solution, Bausch & Lomb), for 28 days. They wore the same lens type for the duration of the study and were evaluated on days 0, 14 and 28 of each treatment period. Subjective ratings of comfort and satisfaction were significantly different between regimens, with the majority of variables in favour of Regimen 1 (P < 0.05). Corneal staining was significantly greater with the Group II, Regimen 2 combination (P < 0.0001). Group IV lenses cared for with Regimen 1 had significantly less residual lysozyme on Day 28 (562 microg) than lenses cared for with Regimen 2 (1145 microg; P < 0.0001). While both products offer the convenience of a 'no rub' regimen, differences in performance should be considered when recommending these solutions to patients.     

Impact of virus aggregation on inactivation by peracetic acid and implications for other disinfectants

Viruses in wastewater and natural environments are often present as aggregates. The disinfectant dose required for their inactivation, however, is typically determined with dispersed viruses. This study investigates how aggregation affects virus inactivation by chemical disinfectants. Bacteriophage MS2 was aggregated by lowering the solution pH, and aggregates were inactivated by peracetic acid (PAA). Aggregates were redispersed before enumeration to obtain the residual number of individual infectious viruses. In contrast to enumerating whole aggregates, this approach allowed an assessment of disinfection efficiency which remains applicable even if the aggregates disperse in post-treatment environments. Inactivation kinetics were determined as a function of aggregate size (dispersed, 0.55 and 0.90 μm radius) and PAA concentration (5-103 mg/L). Aggregation reduced the apparent inactivation rate constants 2-6 fold. The larger the aggregate and the higher the PAA concentration, the more pronounced the inhibitory effect of aggregation on disinfection. A reaction-diffusion based model was developed to interpret the experimental results, and to predict inactivation rates for additional aggregate sizes and disinfectants. The model showed that the inhibitory effect of aggregation arises from consumption of the disinfectant within the aggregate, but that diffusion of the disinfectant into the aggregates is not a rate-limiting factor. Aggregation therefore has a large inhibitory effect if highly reactive disinfectants are used, whereas inactivation by mild disinfectants is less affected. Our results suggest that mild disinfectants should be used for the treatment of water containing viral aggregates.     

Bacterial biofilm in silver-impregnated contact lens cases

PurposeThis study investigated the efficacy of pre-conditioning lens cases on bacterial biofilm formation and removal.MethodsSilver impregnated (MicroBlock / ProGuard™ & i-Clean) and control storage cases were pre-conditioned for 24 h with their respective multipurpose solutions (MPDSs). Cases were then inoculated with 2 ml of 10⁶ CFU/mL of ocular isolates of either P. aeruginosa or S. aureus and incubated for 48 h. Cases were subsequently disinfected (4−6 hours) as per the manufacturer’s recommended disinfecting time (MRDT) followed by the recommended case hygiene procedures - recapping wet (MicroBlock / ProGuard™ cases only) or rinse and air-dry or rinse, tissue-wipe and air dry (mechanical disruption). Surviving bacteria were enumerated using standard techniques.ResultsPre-conditioning the MicroBlock / ProGuard™ cases with MPDS significantly reduced biofilm formation (-1.1 log₁₀ CFU, p < 0.01 for P. aeruginosa & -1.3 log₁₀, p < 0.001, CFU for S. aureus) compared to the i-Clean lens cases. Maintaining the MicroBlock / ProGuard™ lens cases wet after the MRDT resulted in partial removal of bacterial biofilms (-2.9 log₁₀ CFU, p < 0.001 for P. aeruginosa and -2.6 log₁₀ CFU, p < 0.001 for S. aureus). Air-drying of all three types of lens storage cases after MRDT significantly reduced the bacterial biofilm (-5.4 log₁₀ CFU, p < 0.001 for P. aeruginosa and -3.5 log₁₀ CFU, p < 0.001 for S. aureus). Mechanical disruption produced the greatest reduction in the levels of bacterial biofilm in all 3 types of lens cases tested (-6.8 log₁₀ CFU, p < 0.001 for P. aeruginosa and -4.5 log₁₀ CFU, p < 0.001 for S. aureus). Synergi MPDS was significantly better than AQuify MPDS in removing bacterial biofilm from all 3 lens case types for case hygiene treatments with an air-drying step.ConclusionPre-conditioning of silver-impregnated ProGuard™ lens cases inhibited initial bacterial biofilm formation. Synergi MPDS was more effective than AQuify MPDS in removing bacterial biofilm in silver impregnated cases and tissue-wiping significantly improved biofilm removal.     

Lens parameter changes under in vitro and ex vivo conditions and their effect on the conjunctiva

PurposeTo quantify changes in contact lens parameters induced by lens wear and determine whether these changes are associated with contact lens-induced conjunctival staining (CLICS).MethodsIn vitro: Lens diameter, sag, edge shape, base curve of six contact lens brands (balafilcon, comfilcon, etafilcon, lotrafilcon B, omafilcon and senofilcon) measured at 21 °C and 35 °C (eye temperature). Ex vivo: Diameter of lenses collected from a prospective, randomised, contra-lateral, cross-over clinical trial from 36 subjects wearing all lens types for 1 week daily wear, measured in 35 °C PBS after removal. Ocular surface was examined for lens-induced conjunctival staining by masked examiner.ResultsIn vitro: Changes in diameter and base curve outside ISO tolerance were found with etafilcon A and omafilcon A. Ex vivo: Comfilcon A and etafilcon A had greatest shrinkage in diameter (0.18 mm) and base curve (0.11 mm steeper) with temperature increase from 21 °C to 35 °C. Senofilcon A, lotrafilcon B and balafilcon A maintained most stable parameters between 21 °C and 35 °C. Changes in diameter and base curve from lens wear were not correlated with CLICS (p > 0.49). Multivariate analysis showed significantly greater levels of lens induced staining were associated with lens modulus (p < 0.001) and knife (p < 0.001) and chisel (p < 0.001) edge shapes.ConclusionsParameter changes induced by lens wear were associated with increasing temperature, but these changes in lens diameter and base curve did not induce CLICS. Modulus and edge shape were associated with increased CLICS. The susceptibility of etafilcon A and omafilcon A lenses to parameter changes might be related to their high water content.     

Antimicrobial activities of polyhexamethylene biguanide against biofilm-producing Prototheca bovis causing bovine mastitis

Prototheca spp. is a frequent cause of bovine mastitis and is highly resistant to commonly used disinfectants. This study aimed to: (1) evaluate the antimicrobial activity of polyhexamethylene biguanide (PHMB) against mastitis-causing Prototheca spp., and (2) evaluate the biofilm production ability of Prototheca spp. A total of 85 Prototheca bovis and 2 Prototheca blaschkeae isolates from bovine mastitis cases were submitted to biofilm production assays and antimicrobial susceptibility tests against PHMB and disinfectants commonly used in dairy herds (chlorhexidine digluconate, povidone-iodine, sodium dichloroisocyanurate, and sodium hypochlorite). The minimal inhibitory concentration (MIC) and minimal algicidal concentration (MAC) were determined by microdilution assays. We observed that PHMB (MIC₉₀: ≥2 µg/mL and MAC₉₀: ≥4 µg/mL) and chlorhexidine gluconate (MIC₉₀ and MAC₉₀: ≥2 µg/mL) presented the highest antimicrobial activity against P. bovis isolates, followed by sodium dichloroisocyanurate (MIC₉₀ and MAC₉₀: ≥1,400 µg/mL), sodium hypochlorite (MIC₉₀ and MAC₉₀: ≥2,800 µg/mL), and povidone-iodine (MIC₉₀ and MAC₉₀: ≥3,200 µg/mL). Concerning P. blaschkeae isolates, PHMB (MIC and MAC ≥1 µg/mL) and chlorhexidine gluconate (MIC and MAC ≥1 µg/mL) were the disinfectants that presented the lowest concentration values required to inhibit the isolates. Regarding biofilms formation, 63.5% (n = 54/85) of the P. bovis isolates were classified as strong, 28.3% (n = 24/85) moderate, and 8.2% (n = 7/85) weak biofilm producers. In contrast, the P. blaschkeae isolates were classified as weak and moderate biofilm producers. These findings suggest that PHMB has the potential to be used for teat and milking-equipment disinfection for the prevention of mastitis-causing Prototheca spp. in dairy herds.     

Susceptibility of Vibrio parahaemolyticus to disinfectants after prior exposure to sublethal stress

In the present study, Vibrio parahaemolyticus 690 in phosphate buffered-saline containing 3% NaCl was subjected to sublethal stresses: heat shock at 42 °C for 15 min, acid adaptation at pH 5.0 for 30 min, or cold shock at 20 °C for 4 h. The effect of sublethal stress on the susceptibility of V. parahaemolyticus to a chlorine-containing disinfectant (Clidox-S) and a quaternary ammonium compound (Quatricide) at 25 and 40 °C was investigated. It was found that the sublethal stresses examined enhanced the resistance of V. parahaemolyticus 690 to both disinfectants. Depending on the kinds of sublethal stress, V. parahaemolyticus 690 showed various degrees of enhanced resistance to disinfectants. Furthermore, the phenomenon of enhanced resistance to the disinfectants was more marked at 40 than at 25 °C.     

Antimicrobial susceptibility of bacterial isolates from the conjunctiva,storage cases and mobile phones of university students using contact lenses

Purpose: To investigate the presence of bacterial pathogens on the palpebral conjunctiva, mobile phones, and storage cases of contact lens wearers to study any possible correlation between types of bacteria isolated from the 3 sites and to determine their antibiotic profiles.Methods: One hundred and eighty nine swabs from the conjunctiva, mobile phones, and storage cases were collected from 63 contact lens wearing university students. The swabs were collected and transported to the microbiology laboratory within one hour and inoculated on nutrient agar, MacConkey agar, blood agar and mannitol salt agar. The subsequent bacterial isolates were identified by their cultural, morphological and biochemical characteristics.Results: Nine bacterial species were isolated and identified in the current study namely: Staphylococcus. aureus, Streptococcus. pyogenes, Enterococcus. faecalis, Shigella dysentery, Pseudomonas aeruginosa, Proteus mirabilis, Citrobacter spp., Klebsiella pneumoniae and Escherichia coli. Nine (26%) mobile phone and 7 (21%) conjunctival samples were contaminated with five different bacterial species. The highest level of contamination was detected in contact lens storage cases where 18 (52%) bacterial isolates were detected in cases.Conclusions: The storage cases and mobile phones of contact lens wearing university students were highly contaminated with pathogenic bacteria and may act as a carrier for the transmission of such bacteria to the eye causing eye infections which can be controlled by proper hygiene and using effective disinfectant for storage cases. Pathogenic bacteria were detected with multiple antibiotic resistance indices.     

Aeromonas biofilm on stainless steel: efficiency of commonly used disinfectants

Aeromonas spp. are ubiquitous bacteria widely distributed among aquatic environments that have the ability to form biofilms. This aptitude allows them to persist in water distribution systems, contaminating drinking water, food processing surfaces and ultimately food. For this study, the biofilm‐forming ability of aeromonads was evaluated after 48‐h incubation on stainless steel discs at both 4 and 20 °C. Subsequently, disinfectants based on amphoteric surfactants and chlorine compounds were evaluated regarding the capacity to eradicate preformed biofilm and inhibit biofilm formation. Results obtained demonstrated that all strains under analysis were able to form biofilm at both room and refrigeration temperatures. The chlorine‐based disinfectant demonstrated to be efficient in removing preformed biofilm, but both were unsuccessful in preventing biofilm formation, highlighting the importance of adequate cleaning and disinfection procedures, with emphasis on food processing surfaces.     

脐橙采后免发汗式商品化中温预处理工艺优化

以适时采摘的脐橙为原料,探讨清洗消毒时间、清洗消毒温度以及NaCl、ClO2、NaClO溶液不同质量浓度的清洗消毒剂对脐橙表皮微生物数量的影响,确定脐橙采后免发汗式中温预处理技术的最佳工艺条件。结果表明：脐橙表皮的菌落总数随着清洗消毒时间的延长而不断减少,随着清洗消毒温度的升高先减少后增加;不同质量浓度的消毒剂都一定程度减少了脐橙表皮的菌落总数、青霉菌总数、绿霉菌总数,从微生物数量最大减少量的角度考虑,效果排序为ClO2＞NaClO＞NaCl。从而确定脐橙采后免发汗式中温预处理技术的最佳工艺条件为：清洗消毒时间3 min、清洗消毒温度30～35 ℃、清洗消毒剂为ClO2溶液（0.15 g/L）。     

Determination of some characteristics coccoid forms of lactic acid bacteria isolated from Turkish kefirs with natural probiotic

In this study, a total of 21 coccoid forms of lactic acid bacteria (lactococci) were isolated from Turkish kefir samples. As a result of the identification tests, 21 lactococci isolates were identified as Lactococcus cremoris (11 strains), Lactococcus lactis (4 strains), Streptococcus thermophilus (3 strains) and Streptococcus durans (3 strains). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, diacetyl and acetaldehyde productions of the lactococci were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 2.3-9.9 mg/ml. While Lac. lactis Z13S, Str. durans Z7S, Z8S, Z15S, Lac. cremoris Z9S, Z16S, Z17S, Z19S, Z20S and Z21S strains were not shown hydrogen peroxide, Lac. lactis Z1S and Z2S strains had a maximum hydrogen peroxide (0.17 μg/ml). Lac. lactis Z2S, Z3S, Str. thermophilus Z5S, Z12S, Str. durans Z7S, Z8S, Lac. cremoris Z14S and Z16S strains were not show proteolytic activity, Lac. cremoris Z20S strain produced the maximum amount (0.09 mg/ml) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.18 and 3.96 μg/ml. Antimicrobial effects of the lactococci on Escherichia coli NRLL B-704, Staphylococcus aureus 4-63, Pseudomonas aeruginosa ATCC 29212 were also determined by an agar diffusion method. All of the strains were able to inhibit S. aureus, while Lac. lactis Z1S, Z2S and Lac. cremoris Z6S strains were able to inhibit E. coli and P. aeruginosa. Also, Str. thermophilus Z5S strain were able to inhibit P. aeruginosa.