Summary Shewanella putrefaciens is a marine bacterium and a major microbial cause of spoilage in low temperature stored seafood. A survey of fruits and culinary herbs was undertaken on Australian plants with high antioxidant capacities. Twenty‐eight extracts from thirteen plant species were investigated for the ability to inhibit S. putrefaciens growth. Of these, eight extracts (28.6%) substantially inhibited S. putrefaciens growth. The muntries (Kunzea pomifera), lemon aspen (Acronychia acidula) and desert lime (Citrus glauca) extracts were efficient anti‐S. putrefaciens agents, with MIC values ≤3000 μg mL−1. Of these, the muntries methanolic extract was the most potent growth inhibitor (MIC = 2240 μg mL−1). The aqueous desert lime extract was also an effective growth inhibitor (MIC of 3857 μg mL−1), whilst the methanolic bush tomato (Solanum aviculare), aqueous muntries and Davidson's plum (Davidsonia pruriens) extracts displayed moderate S. putrefaciens growth inhibition. All extracts were nontoxic in the Artemia fransiscana bioassay, with LC50 values (>1000 μg mL−1). Nontargeted HPLC‐QTOF mass spectroscopy (with screening against three compound databases) putatively identified twenty compounds that were present in both inhibitory muntries extracts. The low toxicity of these extracts and their inhibitory bioactivity against S. putrefaciens indicates their potential as natural fish and seafood preservatives.

Marmur (4) developed one of the first detailed comprehensive methods for purifying bacterial DNA. This procedure is now outdated, and can be difficult to follow for those with limited experience in molecular biology. Here, we provide a modernized, simplified protocol for extracting bacterial DNA and discuss how this can be incorporated into microbiology laboratory courses for biology majors.

The low toxicity of the T. ferdinandiana leaf extracts and their potent growth inhibition of axillary and plantar malodour-producing bacteria indicate their potential as deodorant components.

Several species of the bacterial genus Shewanella are well-known dissimilatory reducers of manganese under anaerobic conditions. In fact, Shewanella oneidensis is one of the most well studied of all metal-reducing bacteria. In the current study, a number of Shewanella strains were tested for manganese-oxidizing capacity under aerobic conditions. All were able to oxidize Mn(II) and to produce solid dark brown manganese oxides. Shewanella loihica strain PV-4 was the strongest oxidizer, producing oxides at a rate of 20.3 mg/liter/day and oxidizing Mn(II) concentrations of up to 9 mM. In contrast, S. oneidensis MR-1 was the weakest oxidizer tested, producing oxides at 4.4 mg/liter/day and oxidizing up to 4 mM Mn(II). Analysis of products from the strongest oxidizers, i.e., S. loihica PV-4 and Shewanella putrefaciens CN-32, revealed finely grained, nanosize, poorly crystalline oxide particles with identical Mn oxidation states of 3.86. The biogenic manganese oxide products could be subsequently reduced within 2 days by all of the Shewanella strains when culture conditions were made anoxic and an appropriate nutrient (lactate) was added. While Shewanella species were detected previously as part of manganese-oxidizing consortia in natural environments, the current study has clearly shown manganese-reducing Shewanella species bacteria that are able to oxidize manganese in aerobic cultures. IMPORTANCEMembers of the genus Shewanella are well known as dissimilatory manganese-reducing bacteria. This study shows that a number of species from Shewanella are also capable of manganese oxidation under aerobic conditions. Characterization of the products of the two most efficient oxidizers, S. loihica and S. putrefaciens, revealed finely grained, nanosize oxide particles. With a change in culture conditions, the manganese oxide products could be subsequently reduced by the same bacteria. The ability of Shewanella species both to oxidize and to reduce manganese indicates that the genus plays a significant role in the geochemical cycling of manganese. Due to the high affinity of manganese oxides for binding other metals, these bacteria may also contribute to the immobilization and release of other metals in the environment.

Background:Terminalia ferdinandiana (Kakadu plum) is an endemic Australian plant with an extremely high antioxidant capacity. The fruit has long been used by the first Australians as a nutritional food and as a medicine and recent studies have reported its potent growth inhibitory activity against a broad panel of bacteria. Despite this, T. ferdinandiana extracts are yet to be tested for the ability to inhibit the growth of Bacillus anthracis. Materials and Methods: Solvent extracts were prepared using both the fruit and leaf of Kakadu plum.The ability to inhibit the growth of B. anthracis was investigated using a disc diffusion assay. Their MIC values were determined to quantify and compare their efficacies. Toxicity was determined using the Artemia franciscana nauplii bioassay. The most potent extracts were investigated using non-targeted GC-MS head space analysis (with screening against a compound database) for the identification and characterisation of individual components in the crude plant extracts. Results: Solvent extractions of T. ferdinandiana fruit and leaf displayed good growth inhibitory activity in the disc diffusion assay against B. anthracis. Fruit ethyl acetate and methanolic leaf extracts were particularly potent growth inhibitors, with MIC values of 451 and 377µg/mL respectively. The fruit methanolic and chloroform extracts, as well as the aqueous leaf extracts also were good inhibitors of B. anthracis growth, albeit with lower efficacy (MIC values of 1800 and 1414 µg/mL respectively).The aqueous fruit extract and leaf chloroform extracts had only low inhibitory activity. All other extracts were completely devoid of growth inhibitory activity. Furthermore, all of the extracts with growth inhibitory activity were nontoxic in the Artemia fransiscana bioassay, with LC 50 values >1000 µg/mL. Non-biased GC-MS phytochemical analysis of the most active extracts (fruit ethyl acetate and methanolic leaf) putatively identified and highlighted several compounds that may contribute to the ability of these extracts to inhibit the growth of B. anthracis. Conclusions: The low toxicity of the T. ferdinandiana fruit ethyl acetate and methanolic leaf extracts, as well as their potent growth inhibitory bioactivity against B. anthracis, indicates their potential as medicinal agents in the treatment and prevention of anthrax.