Isolation of bacterial strains able to metabolize lignin from screening of environmental samples.

AIMS: To develop a method to detect bacteria from environmental samples that are able to metabolize lignin. METHODS AND RESULTS: A previously developed UV-vis assay method for lignin degradation activity has been developed for use as a spray assay on agar plates. Nine mesophilic strains were isolated using this method from woodland soil incubated in enrichment cultures containing wheat straw lignocellulose: four Microbacterium isolates, two Micrococcus isolates, Rhodococcus erythropolis (all Actinobacteria) and two Ochrobactrum isolates (Alphaproteobacteria). Three thermotolerant isolates were isolated from the same screening method applied at 45°C to samples of composted wheat straw from solid-state fermentation: Thermobifida fusca and two isolates related to uncharacterized species of Rhizobiales and Sphingobacterium (Bacteroidetes), the latter strain showing tenfold higher lignin degradation activity than other isolates. The isolated strains were able to depolymerize samples of size-fractionated high molecular weight and low molecular weight Kraft lignin, and produced low molecular weight metabolites oxalic acid and protocatechuic acid from incubations containing wheat straw lignocellulose. CONCLUSIONS: A new method for the isolation of bacteria able to metabolize lignin has been developed, which has been used to identify 12 bacterial isolates from environmental sources. The majority of isolates cluster into the Actinobacteria and the Alphaproteobacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Lignin-degrading bacterial strains could be used to convert lignin-containing feedstocks into renewable chemicals and to identify new bacterial lignin-degrading enzymes.

The activity of family 11 xylanases at alkaline pH.

Xylanases have several industrial uses, particularly in baking, modification of animal feed and in pulp bleaching in the paper industry. Process conditions in kraft pulp bleaching generally favour an enzyme that is active at high pH values. The activities of several glycosyl hydrolase family 11 xylanases reported to be active under alkaline conditions were determined under optimal conditions and found to have optima in the pH 5-6 range. Only one enzyme tested, BadX, was shown to have an alkaline pH optimum. Significant activity at pH values higher than 8 appears often to be the result of excess enzyme added to the reaction mixtures so that substrate is limiting. The different nature of laboratory and industrial substrates needs to be taken into consideration in designing assay conditions. In some cases, significant differences were observed in pH profiles generated using a small-molecule substrate when compared to those generated using xylan. We conclude that small-molecule substrates are not a suitable proxy for determining the pH profiles of family 11 xylanases.

Considering abortion: a 12-month audit of records of women contacting a Pregnancy Advisory Service.

OBJECTIVE: To characterise the demographic and psychosocial circumstances of women contacting Victoria's largest public pregnancy advisory service (PAS). DESIGN AND SETTING: Audit of PAS electronic records for the 12 months from 1 October 2006 to 30 September 2007. De-identified data were extracted from a comprehensive electronic database used for recording consultations. MAIN OUTCOME MEASURES: Summary statistics and measures of association. RESULTS: During the 12 months, 5462 women contacted PAS; records were created for 3827 women, and data were available in more than 80% of records for 77% (13/17) of items. Over half of the women receiving pregnancy support from PAS (60%) were 18-29 years old; 12% lived outside the metropolitan area; 51% held a health care card, and smaller percentages faced housing, financial, or drug and alcohol problems; 16% reported violence, but 71% described partners as involved and supportive. Most (79%) made contact within 2 weeks of discovering pregnancy, and 72% were referred by a general practitioner. Later gestation at contact was associated with younger age (P < 0.001), having a health care card (P < 0.001), and living outside the metropolitan area (P < 0.001). The most common reasons for seeking abortion were the desire to delay pregnancy (23%) and family completion (18%); 42% already had at least one child. Twenty-three women reported that the pregnancy was the result of rape. Ten per cent had mental health problems, and smaller numbers faced access barriers and had special needs. CONCLUSIONS: This PAS responds to demand from women with diverse social and personal circumstances. Findings provide evidence for policy, prevention and service development.

Psychiatric morbidity in sentenced segregated HIV-positive prisoners.

In this comparative study with a control group of prisoners, psychiatric morbidity was measured in two groups of sentenced prisoners, each group completing the GHQ-30 and 21-item Beck Depression Inventory (BDI). Group 1 consisted of 40 segregated HIV-positive prisoners and group 2 a matched control group in the main prison who had no history of HIV seropositivity. All members of group 1 had a history of intravenous drug abuse. The mean GHQ-30 and BDI scores were significantly higher in group 1, and 90% of group 1 were psychiatric 'cases' compared with just over 42% of group 2. Levels of psychiatric morbidity present in a third group, consisting of HIV-positive prisoners who had not been segregated (prison authorities were unaware of their seropositivity) are an interesting pointer for further research.