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Thermophilic Campylobacter are commonly associated with poultry as commensals of the avian gut and are the causative agent responsible for human Campylobacteriosis. This study aimed to establish the prevalence of Campylobacter spp. from environmental sources that have previously been implicated as sources of horizontal transmission. The highest prevalence of thermophilic Campylobacter was found in water samples (87.5%) and lowest from flies (7.2%). Only C. jejuni was isolated from all sources. A secondary aim was to provide a baseline of resistance profiles of Campylobacter spp. isolates obtained. Alarmingly all the C. jejuni isolates from environmental sources as well as humans were multi-drug resistant.

Thermophilic Campylobacter spp. are the primary cause of human diarrhea. The common source of infection is contaminated poultry. This study aimed to establish the prevalence of Campylobacter spp. in poultry obtained from ‘pluck shops’ and provide a baseline of resistance profiles of Campylobacter spp. isolates obtained. A biphasic approach, with qualitative detection as well as quantitative enumeration of Campylobacterspp. was used. We examined 240 samples each, of carcasses and cecum of poultry obtained from ‘pluck shops. Amongst the cecum samples and carcasses, 59.5 and 57%, respectively were positive for Campylobacter spp. The average Campylobacter spp.concentration was 2.69 (S.D 0.419) log10 CFU/mL and 4.55 (S.D 0.607) log10 CFU/g for carcass rinsate and cecum, respectively. Of the 225 Campylobacter isolates studied, 76.9% were identified as Campylobacter jejuni and 23.1% as Campylobacter coli. Susceptibilities for 112 strains of C. jejuni and 31 strains of C. coli were determined for 12 antibiotics by the agar diffusion technique. According to the minimal inhibitory concentration, a marked resistance to gentamycin and chloramphenicol was also demonstrated. According to the antibiotic resistance profiles, the isolates appeared to differ from each other. Key words: Campylobacter, seasonality, antibiotic resistance, India, wet-market, pluck-shop

Agricultural productivity to meet growing demands of human population is a matter of great concern for all countries. Use of green compounds to achieve the sustainable agriculture is the present necessity. This review highlights the enormous use of harsh surfactants in agricultural soil and agrochemical industries. Biosurfactants which are reported to be produced by bacteria, yeasts, and fungi can serve as green surfactants. Biosurfactants are considered to be less toxic and eco-friendly and thus several types of biosurfactants have the potential to be commercially produced for extensive applications in pharmaceutical, cosmetics, and food industries. The biosurfactants synthesized by environmental isolates also has promising role in the agricultural industry. Many rhizosphere and plant associated microbes produce biosurfactant; these biomolecules play vital role in motility, signaling, and biofilm formation, indicating that biosurfactant governs plant-microbe interaction. In agriculture, biosurfactants can be used for plant pathogen elimination and for increasing the bioavailability of nutrient for beneficial plant associated microbes. Biosurfactants can widely be applied for improving the agricultural soil quality by soil remediation. These biomolecules can replace the harsh surfactant presently being used in million dollar pesticide industries. Thus, exploring biosurfactants from environmental isolates for investigating their potential role in plant growth promotion and other related agricultural applications warrants details research. Conventional methods are followed for screening the microbial population for production of biosurfactant. However, molecular methods are fewer in reaching biosurfactants from diverse microbial population and there is need to explore novel biosurfactant from uncultured microbes in soil biosphere by using advanced methodologies like functional metagenomics.

A total of 31 Acinetobacter isolates were obtained from the rhizosphere of Pennisetum glaucum and evaluated for their plant-growth-promoting traits. Two isolates, namely Acinetobacter sp. PUCM1007 and A. baumannii PUCM1029, produced indole acetic acid (10-13 microgram/ml). A total of 26 and 27 isolates solubilized phosphates and zinc oxide, respectively. Among the mineral-solubilizing strains, A. calcoaceticus PUCM1006 solubilized phosphate most efficiently (84 mg/ml), whereas zinc oxide was solubilized by A. calcoaceticus PUCM1025 at the highest solubilization efficiency of 918%. All the Acinetobacter isolates, except PUCM1010, produced siderophores. The highest siderophore production (85.0 siderophore units) was exhibited by A. calcoaceticus PUCM1016. Strains PUCM1001 and PUCM1019 (both A. calcoaceticus) and PUCM1022 (Acinetobacter sp.) produced both hydroxamate- and catechol-type siderophores, whereas all the other strains only produced catechol-type siderophores. In vitro inhibition of Fusarium oxysporum under iron-limited conditions was demonstrated by the siderophore-producing Acinetobacter strains, where PUCM1018 was the most potent inhibitor of the fungal phytopathogen. Acinetobacter sp. PUCM1022 significantly enhanced the shoot height, root length, and root dry weights of pearl millet seedlings in pot experiments when compared with controls, underscoring the plant-growth-promoting potential of these isolates.

Acinetobacter calcoaceticus HIRFA32 from wheat rhizosphere produced catecholate type of siderophore with optimum siderophore (ca. 92 % siderophore units) in succinic acid medium without FeSO4 at 28 °C and 24 h of incubation. HPLC purified siderophore appeared as pale yellow crystals with molecular weight [M+1] m/z 347.18 estimated by LCMS. The structure elucidated by 1H NMR, 13C NMR, HMQC, HMBC, NOESY and decoupling studies, revealed that siderophore composed of 2,3-dihydroxybenzoic acid with hydroxyhistamine and threonine as amino acid subunits. In vitro study demonstrated siderophore mediated mycelium growth inhibition (ca. 46.87 ± 0.5 %) of Fusarium oxysporum. This study accounts to first report on biosynthesis of acinetobactin-like siderophore by the rhizospheric strain of A. calcoaceticus and its significance in inhibition of F. oxysporum. Electronic supplementary material The online version of this article (doi:10.1007/s12088-014-0446-z) contains supplementary material, which is available to authorized users.

A total of 31 Acinetobacter isolates were obtained from the rhizosphere of Pennisetum glaucum and evaluated for their plant-growth-promoting traits. Two isolates, namely Acinetobacter sp. PUCM1007 and A. baumannii PUCM1029, produced indole acetic acid (10-13 microgram/ml). A total of 26 and 27 isolates solubilized phosphates and zinc oxide, respectively. Among the mineral-solubilizing strains, A. calcoaceticus PUCM1006 solubilized phosphate most efficiently (84 mg/ml), whereas zinc oxide was solubilized by A. calcoaceticus PUCM1025 at the highest solubilization efficiency of 918%. All the Acinetobacter isolates, except PUCM1010, produced siderophores. The highest siderophore production (85.0 siderophore units) was exhibited by A. calcoaceticus PUCM1016. Strains PUCM1001 and PUCM1019 (both A. calcoaceticus) and PUCM1022 (Acinetobacter sp.) produced both hydroxamate- and catechol-type siderophores, whereas all the other strains only produced catechol-type siderophores. In vitro inhibition of Fusarium oxysporum under iron-limited conditions was demonstrated by the siderophore-producing Acinetobacter strains, where PUCM1018 was the most potent inhibitor of the fungal phytopathogen. Acinetobacter sp. PUCM1022 significantly enhanced the shoot height, root length, and root dry weights of pearl millet seedlings in pot experiments when compared with controls, underscoring the plant-growth-promoting potential of these isolates.

Strains belonging to the genus Acinetobacter and their plant growth-promoting properties have been reported in the literature. However, there is a paucity of information on the diversity of Acinetobacter species associated with the wheat rhizosphere. In the present investigation, Acinetobacter species diversity was assessed in the rhizosphere of wheat from three agricultural fields where different varieties were cultivated. The Acinetobacter species diversity was assessed by DGGE (Denaturing Gradient Gel Electrophoresis) of 16S rRNA gene PCR products amplified from total soil DNA using genus-specific primers. Ac. calcoaceticus, Ac. baumannii, Ac. lwoffii, Ac. baylyi and Acinetobacter sp. were detected in the rhizosphere of wheat. Prevalence of Acinetobacter species in the rhizosphere of wheat was also investigated by a cultivation-dependent approach. Ac. calcoaceticus, Ac. baumannii, Ac. lwoffii and Acinetobacter sp. were isolated on selective media from the same samples. In vitro characterization of Acinetobacter isolates revealed that majority of these bacteria exhibited plant growth-promoting traits such as nitrogen fixation, siderophore production and mineral solubilization. These Acinetobacter strains may play a favorable role in plant growth promotion while residing in the rhizosphere of wheat.